At the heart of considerations about how best to regulate e-cigarettes is the extent to which the potential benefits of making available a product that may help people quit smoking might be outweighed by several potential risks. Risks identified to date include uptake by young people who have never smoked, gateway effects, health harms and prolonged addiction associated with dual use, relapse to smoking among people who have successfully quit, renormalisation of nicotine addiction, and allowing the nicotine and tobacco industries to influence decision-making in public health (see Section 18.8 for a discussion of potential population-level risks and benefits).1-3
People who have never smoked who vape generally report doing so out of curiosity or for fun. There is no question that vaping increases harm compared with not vaping among this group, and the central question for public health is the extent to which vaping leads to nicotine addiction, health harms, and, even more concerningly, subsequent uptake of smoking. See Section 18.6.2 for a discussion of health risks of vaping for young people.
People who already smoke who use e-cigarettes commonly report vaping to try and help them cut down or quit smoking, because they perceive it as cheaper and/or healthier than smoking, or because they can vape in places that smoking is not allowed or acceptable4 (see Section 18.12). As indicated in Section 3.36, many health risks for people who smoke are not meaningfully reduced by cutting down the number of cigarettes smoked (i.e. social or ‘light’ smoking). Crucial to assessing the potential individual and public health benefits of e-cigarette use, then, is whether such use promotes successful and sustained smoking cessation.5 That is, whether use of e-cigarettes increases:
The enormous benefits of quitting smoking at the individual and population-level are indisputable (see Section 3.38). However, as evidence accumulates on the potential health harms of e-cigarette use (see Section 18.6), it is also important to consider whether vaping for smoking cessation will lead to different or additional risks for those who continue to vape long-term. Complete cessation of all tobacco and nicotine products is therefore the optimal approach to maximise health benefits.
A more recent Australian study found that adolescents aged 12–17 who had vaped were nearly 5 times more likely to start smoking than those who had never vaped, with the relative risk of smoking uptake substantially higher among younger compared with older adolescents.13 Additional longitudinal studies,14-28 and several less extensive reviews29-31 and meta-analyses,32-39 have similarly concluded that e-cigarette use is associated with an increased risk of cigarette smoking. Longitudinal research in the UK found that among 10–25-year-olds, the likelihood of e-cigarette users transitioning to smoking rose over time from 14% in year one to 27% in year five. Those aged 14–17 were more likely to make this transition than older adolescents and young adults.40 Another UK study found that among a cohort born in 2000–2001, those who had never vaped had an almost zero probability of smoking at age 17. In contrast, those who currently vaped had a probability of smoking similar to that of the high-smoking cohort of youth born over 4 decades earlier in 1958.26
While the relationship between vaping and smoking uptake is clear, the question of causation continues to be debated. E-cigarette use could be a marker in young people who would have gone on to smoke regardless; that is, the relationship between vaping and smoking could be explained by other variables, such as social—environmental factors, or a common genetic vulnerability.33,34,41-46 Research in the US,47 China,48 and Australia49 does demonstrate that adolescents who are susceptible to smoking are significantly more likely to report e-cigarette use; however, several studies have also noted smoking uptake among e-cigarette users who would generally be considered least at risk of smoking.50-55 E-cigarette use is associated with an increase in smoking, even among adolescents not susceptible to smoking, and even when studies control for a range of factors associated with smoking uptake.52
Several factors appear to affect the strength of the relationship between vaping and smoking uptake among young people. Compared with older teenagers, onset of e-cigarette use at a younger age appears to be associated with increased odds of smoking.13,56-58 The relationship between e-cigarette use and smoking uptake may also be stronger among boys than girls.59,60 As noted above, e-cigarette use is more common among people susceptible to cigarette smoking.47-49,61 Other studies have found that factors such as more frequent vaping,62 higher nicotine content,9 device type,63 mental health symptoms,64,65 White race (compared with Black),66, 67 and middle socioeconomic status (compared to low),66 increase the likelihood of transitioning from e-cigarette use to cigarette/dual use. Use of e-cigarettes among youth and young adults may increase consumption of conventional cigarettes and duration of smoking.8,68,69
The relationship between vaping and smoking appears to be bi-directional, such that smoking increases the risk of e-cigarette use, and e-cigarette use increases the risk of smoking.40,70-75 In addition to cigarette smoking, e-cigarette susceptibility and use may also predict uptake of other types of tobacco products,18,76,77 as well as marijuana, alcohol, and other drug use over time.28,78-89 Such relationships may also be bidirectional, with vaping predicting uptake of other drugs.90
Several possible mechanisms of how e-cigarette use could act as a ‘gateway’ to smoking have been proposed.91,92 Vaping among peers, friends and family members may normalise nicotine use, and is related to positive attitudes and susceptibility to smoking.93,94 Another explanation is that vaping could reduce psychological boundaries that operate in defining oneself as either a ‘smoker’ or a ‘non-smoker’. E-cigarette users are able to practise and become accustomed to the behaviours and rituals associated with smoking without the risk or stigma of tobacco smoke, potentially facilitating the transition into a role that would otherwise have been resisted. A third explanation is more biological and involves the effects of nicotine on the brain. Animal and human studies suggest that nicotine is a ‘gateway’ drug, such that nicotine use may lead to particular changes in the brain that prime and enhance responses to subsequent drugs. These effects appear to be even stronger among adolescents.95 Vaping can expose young people to very high levels of nicotine, and nicotine use among adolescents can lead to rapid addiction and impact the developing brain (see Section 18.6.2). Nicotine addiction and its associated changes in the adolescent brain could therefore facilitate smoking experimentation and uptake.39,50 Consistent with this theory, use of e-cigarettes with higher concentrations of nicotine has a stronger association to later cigarette use.9,96
In contrast to the gateway theory, some commentators have suggested that, rather than acting as a ‘gateway’, e-cigarettes may be acting as a ‘diversion’ among young people. That is, e-cigarette use partially or wholly replaces cigarette smoking, and may therefore accelerate the decline in youth cigarette smoking.97 They note that increases in use of non-cigarette tobacco/nicotine products has increased substantially in the US97 and UK,98 alongside a decline in cigarette smoking. Several studies from the US have concluded that a long-term decline in smoking prevalence among youth and young adults accelerated after e-cigarette use became more widespread, which the authors argue demonstrates that e-cigarette use has not increased youth smoking at the population level and may support the diversion theory.99-101 Another contended that data on adolescent tobacco/nicotine use from 2000 to 2019 in the US is more consistent with a diversion effect than a catalyst/gateway effect.102 Critics of diversion theory however argue that continued declines in smoking might alternatively be attributed to the continuing and long-term effects of current and historical comprehensive tobacco control programs.103,104 To put it another way, declines may have been accelerating due to the cumulative and social contagion effects of previous decades of policy, and may have been steeper still without e-cigarette use. Several US studies conclude that there was a slower decline in current cigarette smoking among young people following the introduction of e-cigarettes, suggesting that e-cigarettes are not acting as a substitute for cigarettes.105,106 Recent studies in Australia and Aotearoa/New Zealand have similarly found that the rate of decline in smoking among young people slowed markedly after the emergence of vaping,107,108 including among Māori, Pacific, and Asian adolescents in Aotearoa/New Zealand.109 Concerning data from Great Britain shows a sharp increase in the proportion of young people aged 11–17 who had ever tried smoking from 14% in 2023 to 21% in 2025, which follows an almost doubling of young people who had tried vaping (11% in 2021 to 20% in 2023). There was also a significant increase in 2025 in never smokers reporting that they intend to smoke in the future.110
Some researchers have argued that any gateway effect of vaping to smoking is likely to only have a small impact on youth smoking prevalence at the population level.111 A recent cohort study in the US examined the risk of smoking initiation after vaping and additionally, the risk of smoking becoming an established, regular habit. In line with the gateway theory, it found that ever e-cigarette users were about twice as likely, and current users about 4.5 times as likely, to report subsequent established smoking (defined as 100 cigarettes or more in the respondent’s lifetime and smoking currently). This represented non-significant ‘adjusted risk differences’ (calculated as risk with e-cigarette use minus risk without e-cigarette use, adjusted for covariates) of 0.60 percentage points for ever users and 1.79 percentage points for current users.112 Nonetheless, with very recent large increases in vaping among young people in many countries, even small increases in the absolute risk of smoking will translate to thousands of additional young people smoking as a result of vaping. Any changes in the prevalence of smoking among young people—and whether these changes could potentially renormalise tobacco use among adolescents—are likely to be intensely studied over the coming years.
A number of studies have found that people who smoke who use e-cigarettes are more likely to attempt to quit conventional cigarettes,118-128 though one meta-analysis found conflicting results depending on whether the studies were retrospective (which showed increased quit attempts) or prospective (which showed no differences).129 Users of e-cigarettes may be more motivated to quit smoking than those who do not use them,9 with research showing that dual users who predominantly vaped (compared with those who predominantly smoked) were more likely to report using e-cigarettes as a cessation aid.130 Though, use of e-cigarettes among people who smoke who are unmotivated to quit may also prompt quitting thoughts and behaviours.131,132 Research in the US found no association between use of e-cigarettes and attempts to quit smoking among teenagers,133 while among adults, use of e-cigarettes to quit smoking was associated with more frequent quit attempts among people who had tried but failed to quit.128 A longitudinal study in Mexico found that while people who vape were more likely to try and quit smoking, they were no more likely to sustain abstinence.134
The use of e-cigarettes as a cessation aid has increased over time in Australia, and they are now one of the most popular products for people trying to quit smoking.135 Clinical guidelines state that health professionals may consider recommending therapeutic vapes for smoking cessation when a person has been unable to quit using first-line therapies (a combination of behavioural support and registered smoking cessation medicines).136 Major reviews of the effectiveness of e-cigarettes as a cessation aid have been published since 2018 by Public Health England,7 the US National Academies of Sciences, Engineering, and Medicine,8 the NHMRC10 and CSIRO9 in Australia, the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER),11 the US Preventive Services Task Force (USPSTF),137 and the US Surgeon General.138 Overall these major reviews have generally concluded that the use of e-cigarettes containing nicotine may be associated with increased smoking cessation. A systematic review and meta-analysis commissioned by the Australian government and published in 2022 that was considered by Australia’s National Health and Medical Research Council10 concluded that there is ‘limited evidence’ that, in the clinical context in combination with best-practice counselling and supportive care, freebase nicotine e-cigarettes may be more efficacious for long-term (i.e., >four months) smoking cessation than NRT, and than no intervention or usual care.139
Several systematic reviews and meta-analyses of clinical trials (which provide the highest level of evidence) have examined the effectiveness of e-cigarettes for cessation,36,140-143,104,105 most of which conclude that users of e-cigarettes were more likely to successfully quit than users of NRT36,141,142,144,145 and than those in control conditions (e.g., usual care, counselling, or non-nicotine e-cigarettes).36,141,142,146 A recent overview of reviews concluded that higher-quality reviews consistently supported the effectiveness of nicotine e-cigarettes over other interventions, while the results of lower-quality reviews were more varied.147
The most recent in a series of Cochrane reviews that examine e-cigarettes for smoking cessation was published in late 2025 and concluded that there was high certainty evidence that users of nicotine e-cigarettes were more likely to successfully quit than those who used NRT. However, the analysis did not distinguish between single-product and combination NRT, the latter of which is known to be more effective.148 Another Cochrane review of the evidence on all of the major pharmacotherapies for smoking cessation published in 2023 found that the benefits of nicotine e-cigarettes were comparable to those of varenicline and cytisine (see Section 7.16) and likely similar to combination NRT.149 Additional studies have also found that nicotine e-cigarettes are about as effective as (i.e. just as effective but not significantly more effective than) varenicline150,151 and combination NRT152 for smoking cessation. Initial economic analyses also suggest that the provision of e-cigarettes alongside behavioural support may be a cost-effective strategy for smoking cessation.153
Some have argued that the increased risk of prolonged dual use among those assigned to e-cigarettes in clinical trials has not been adequately acknowledged or reported.154-156 A meta-analysis published in 2022 notes that the use of e-cigarettes for cessation is more likely to lead to extended dependence on nicotine and long-term e-cigarette use,157 the long-term health risks of which are largely unknown (see Section 18.6). Authors of one review suggest that that e-cigarettes could be considered on a prescription basis with clinical supervision, and after considering potential benefits as well as risks such as these.158
A review of the design of studies examining e-cigarettes for smoking cessation found that such studies vary widely in their duration and samples, and often lack robust compliance measures (e.g. biochemical verification of use status).159 An overview of 14 systematic reviews judged half as higher quality and half as lower quality, with those judged as lower quality often failed to adequately list and justify excluded studies, not consider risk of bias, and not investigate publication bias.147
Population groups identified in national strategies as priorities for reducing smoking prevalence include those that have much higher smoking rates (e.g. people with lower levels of income or education and those with mental illness), or for whom smoking causes unique or disproportionate harms (e.g. people who are pregnant)—see InDepth 9A. Early studies have begun investigating the feasibility of e-cigarettes for smoking cessation among these groups; for example, people experiencing homelessness.160,161
Given the disproportionate burden of smoking-related harm experienced by people with mental illness, some researchers162-165 and organisations166 have advocated the use of e-cigarettes as a smoking reduction or cessation aid for people with mental disorders (see Section 18.6.10 for a discussion of the relationship between vaping and mental health). Some preliminary evidence suggests that vaping may be a helpful smoking cessation aid for people with psychiatric disorders.167-170 An Australian trial comparing nicotine vapes and NRT for smoking cessation among people experiencing social disadvantage who were willing to quit smoking concluded that vapes were more effective.171 A limitation of the trial was that participants only had the choice of either fast-acting NRT lozenges or gum; they were not offered a combination of fast- and slow-acting NRT, a treatment regime known to be more effective in supporting cessation (see Section 7.16). Another Australian trial that did compare combination NRT with e-cigarettes among people with substance use disorders, both combined with Quitline counselling, found promising cessation rates with no differences in effectiveness between the two products.168
A number of recent studies have examined the efficacy of e-cigarettes as a cessation aid during pregnancy172 (for a discussion of their safety, see Section 18.6.1). An RCT in the US suggests that the timing of e-cigarette uptake may affect smoking cessation. It found that those e-cigarette users who had started vaping before pregnancy had a higher smoking abstinence rate in late pregnancy than NRT users, while new e-cigarette users had a similar smoking abstinence rate to NRT users.173 An RCT in England and Scotland found that e-cigarettes appeared to be more effective than NRT in helping pregnant people who smoke to quit; however treatment adherence and validated abstinence were low.174,175 Longitudinal research in England found that e-cigarette use during pregnancy may be associated with a lower likelihood of returning to smoking postpartum.176
Guidelines in some countries support the use of e-cigarettes as a cessation aid during pregnancy as a last resort for those unwilling or unable to use other medications.177 Due to insufficient information on their effects on foetal development and obstetric outcomes, Australian guidelines do not recommended e-cigarettes as a smoking cessation aid for people who are pregnant or breastfeeding.178
A number of studies have attempted to assess whether some patterns of use of e-cigarettes may be more helpful in assisting users achieve smoking cessation than others. Studies generally find that sustained and frequent e-cigarette users are more likely to reduce cigarette consumption179 or successfully quit121,138,158,180-197 than those who use the products short-term or intermittently. Infrequent e-cigarette users may be less likely to quit, with research showing an association between non-daily use and both lower motivation to quit180 and lower rates of successful cessation.158,183,188,194,198,199 This may be partly explained by research showing that dual users who vape more frequently are more likely than those who vape less frequently to cite quitting or reducing smoking as a reason for vaping.130,200
A recent systematic review of the role of flavours in quitting found low certainty evidence that there is no association between use of flavoured vapes and increased quit intentions or attempts compared to tobacco-flavoured vapes. It also found very low certainty evidence that using non-tobacco flavours did not increase quitting success compared to using tobacco/unflavoured vapes, nor did use of non-menthol and non-tobacco flavours compared to tobacco and menthol-flavoured vapes.201 A secondary analysis of the Cochrane review of e-cigarettes for smoking cessation similarly did not find any clear evidence of an association between flavours and cessation, though noted the paucity of data.202 An update of this review in 2025 reached the same conclusion.203 An analysis of PATH data in the US found that an increasing trend in quitting smoking was not specific to any particular flavour/s of e-cigarettes or device types,204 though other studies have found that use of disposable e-cigarettes may be associated with a lower likelihood of quit attempts and successful cessation compared with other product types.189,190,205,206 One trial found that cessation rates were comparable between those who used higher or lower wattage e-cigarettes.207
Studies have also begun examining the effectiveness of combining e-cigarettes with cessation medications, with some small studies suggesting this approach shows promise.208-210
A number of population-level studies have explored the association between e-cigarette use and quit rates in the ‘real world’ (i.e., outside of clinical trials).187,211-214 That is, whether declines in smoking prevalence in some countries can be attributed to the increasing use of e-cigarettes. Initial reviews of research up to 2019 did not find evidence that e-cigarettes increase quitting at the population level.158,215 Several more recent studies in England have suggested that e‐cigarette use is associated with increased rates of successful quit attempts and/or overall quit rates,7,213,216-218 particularly among middle-aged and younger people.219 Another study in England concluded that a government initiative providing free vape starter kits alongside behavioural support was associated with an increase in people using vapes for quit attempts, though it was not able to examine successful cessation.220 Cr oss-sectional research in Australia,221,222 New Zealand,223 the US,224 Germany,225 France,226 and in the EU227 has found an association between e-cigarette use and smoking cessation, though research in Italy has not.228 Research in Ireland found that while in 2015 dual use was strongly associated with higher odds of quit intentions and attempts compared to tobacco-only use, in 2023 the relationship between dual use and quitting intentions had substantially diminished, and there was no longer an association between dual use and quit attempts.229
Initial evidence from the longitudinal PATH study in the US found that e-cigarette use was not associated with increased cessation among adults who smoke compared with non-e-cigarette users230-233 or compared with users of NRT or cessation medications.232,234 PATH data between 2016 and 2019 has shown that among those who tried to quit smoking in the past year, the use of NRT or prescription medications was more effective than e-cigarettes in achieving long-term cessation.235 More recent analyses have found that while rates of quitting were no higher among e-cigarette users in earlier survey years (before 2016), between 2018/19 and 2021 rates of quitting were significantly higher among people who vaped. The authors speculate that increases in frequency of use and changes in product features may account for these differences over time.236,237 Additional cohort studies looking at recent waves have found that daily vaping was associated with increased odds of abstinence among people using e-cigarettes to quit smoking,238,239 and another longitudinal study found that daily but not non-daily vaping was associated with short-term abstinence.240 However, another analysis of PATH data found that while daily vaping was associated with cessation in unadjusted analyses, once a range of confounders were adjusted for, there was no significant difference in smoking cessation among people who smoked and vaped daily, compared with people who smoked and did not vape. Cessation was significantly lower among people who smoked who vaped non-daily compared with not at all.198 A review of studies using PATH data noted substantial variation in study characteristics and cautioned against relying on a single paper to make definitive claims about e-cigarette use and cessation. It concludes that the weight of evidence suggests that daily vaping may promote smoking cessation, and that studies which restricted participants to those with quit intentions were less likely to observe cessation than studies that included participants regardless of quit intention.241
Longitudinal research in Aotearoa New Zealand found that those who vaped were just as likely to transition to smoking as those who smoked were to transition to vaping. The authors suggest that declining smoking prevalence is better explained by other factors such as public education campaigns and increased tobacco taxes.242 Another US PATH study examined transitions between tobacco and e-cigarettes. Among those who smoked, an estimated 2.1 million people transitioned to exclusive vaping or quit smoking by using e-cigarettes (‘beneficial’ transitions), while an estimated 4.6 million people who had never smoked took up vaping or moved from exclusive vaping to smoking (‘harmful’ transitions). That is, for every beneficial transition, there were approximately 2.15 harmful transitions.243 Research in Taiwan244 and the US245 also notes that e-cigarette use does not appear to be associated with smoking cessation among adolescents.
Given the higher likelihood of long-term e-cigarette use among those who use the products as a smoking cessation aid,246 it is important to examine whether such use prevents or facilitates relapse to smoking. Research in England shows an increase over time in the uptake of vaping after successful smoking cessation (i.e. vaping that was not attributable to having used e-cigarettes to quit smoking), including among those who had quit many years earlier.247 Data from the ITC Four Country study showed no differences in relapse in 2018 between ex-smokers who were vaping in 2016 compared to those who were not vaping.248 An RCT in the UK found that relapse rates were lower among participants who had quit who used e‐cigarettes compared with those who did not use e‐cigarettes.249 However, longitudinal studies in France,212 the US,250-256 and the UK257 have found an increased risk of relapse among people who have quit smoking who use e-cigarettes. Some studies have noted differences in relapse risk depending on frequency of vaping and smoking history, with the risk appearing to be higher among long-term quitters than among those who have recently stopped smoking212 and among intermittent users compared with those who vape daily.257,258 However, a longitudinal study in the US found an increased risk of relapse among those who had quit smoking between two weeks and two years earlier who vaped either daily or non-daily compared to those who did not vape.240
A systematic review and meta-analysis published in 2021 found evidence that that people who had quit smoking who use e-cigarettes have more than twice the odds of relapse compared with those who have not used e-cigarettes.12 Another similarly concluded that people who had quit who used e-cigarettes—particularly long-term ex-smokers—had an increased risk of relapse to smoking compared with non-e-cigarette users.259 A further recent industry-funded review concluded that findings on the risk of smoking relapse among ex-smokers who use e-cigarettes are mixed and inconsistent.260 A secondary analysis of studies from a Cochrane review examined longer-term (six months or more) smoking abstinence and relapse following use of e-cigarettes and similarly found contradictory results.261 One study using longitudinal US PATH data suggests that differences in how relapse is defined may affect conclusions, with people who vape appearing to be more likely to ‘slip’ (report any smoking in the past year) but no more likely to relapse (report more recent or frequent smoking).262
Studies examining the effects of quitting e-cigarettes on smoking have produced mixed findings. One study using PATH data in the US found a possible risk of relapse among ex-smokers in the short-term following cessation of e-cigarettes,263 suggesting that NRT may be beneficial to support people who have quit smoking who are attempting to quit vaping. In contrast, a secondary analysis of data from an RCT examining vaping cessation found that quitting e-cigarettes was associated with smoking cessation, even though smoking was not a focus of the trial.264
Reduced daily consumption of conventional cigarettes in users of e-cigarettes have been noted in many studies,126,163,179,248,265-269 and reviews;144,270,271 with some authors suggesting that vaping may play an important role in reducing harm among people who smoke who belong to population groups disproportionately affected by smoking (e.g., low socioeconomic status groups).272,273 However, it will be important to continue examining whether reduced cigarette consumption among those who both vape and smoke increases their chances of smoking cessation.
Even following substantial reductions in cigarette consumption, evidence suggests that the health benefits of reduced consumption are limited. Although people who smoke who substantially reduce the number of cigarettes smoked per day reduce their exposure to some harmful and potentially harmful constituents, these decreases are limited and much smaller in magnitude than reductions following complete cessation.274 Several large cohort studies have found that people who smoke who reduce their consumption do not significantly reduce their risk of premature death.275,276 Smoking just 1–4 cigarettes per day significantly increases a person’s risk of dying from smoking-related disease.277 The modesty of the health benefit from smoking reduction is often attributed to compensatory smoking: those who cut down tend to inhale each cigarette more deeply, and smoke more of it.
A number of studies have shown that dual use of NRT and cigarettes can help alleviate the issue of compensation,278-280 leading some to advocate long-term use of NRT in combination with cutting down as a harm reduction strategy.281,282 Researchers have suggested that it may be possible that the use of e-cigarettes while smoking could similarly reduce intake of nicotine and toxins from each cigarette. However, data on the long-term safety of e-cigarettes is lacking, and they may be less safe than existing, licenced NRT products.119,274,283 Further, physiological factors beyond compensation are also relevant to the extent to which risk reduces with reduced consumption. Even low levels of exposure to tobacco smoke cause profound changes in cardiovascular function (See Section 3.36 for further detail).
Dual use refers to the concurrent use of conventional tobacco products and e-cigarettes. Dual use is actively promoted by some e-cigarette manufacturers, especially those that also manufacture tobacco products, as a way for people who smoke to by-pass smokefree regulations,290 and this is a commonly cited reason for vaping.291,292 Other people who smoke use both products as a means of cutting down the number of cigarettes they smoke each day, and/or as an intended pathway to complete smoking cessation.4,5,293 However, many people who smoke are unsuccessful in transitioning fully from smoking to vaping, despite initial intentions to quit smoking.291
Research has found that continued dual use is a relatively common pattern among adults,294-297 including young adults,298 and studies in the US have shown that among dual users, most predominantly smoke (rather than heavy or light use of both, or predominant vaping).130,299 Recent evidence from the UK found that the most common pattern of dual use was daily use of both products.300 Although clinical trial data suggests that dual use may support smoking reduction or cessation,301 population studies show that completely switching from dual use to exclusive vaping appears to be relatively uncommon,302 with several longitudinal studies finding that the majority of dual users transitioned over time to either continued dual use or exclusive smoking.254,295,303-305 A systematic review similarly found that most dual users reverted to exclusive smoking over time.297 Findings from the US PATH studies have shown that a larger proportion of dual users transitioned to exclusive vaping in later compared with earlier waves, and most recently was about the same as the proportion who transitioned to exclusive smoking (24.2% and 26.2% in 2021–22, respectively) and was mostly driven by young adults.306 However, the largest proportion sustained dual use (43.9%),306 and uptake of dual use among people who smoke was very low, limiting the public health impact of any beneficial trends.307 The increased risk of dual use has been flagged as a concern in clinical trials among people who smoke who are allocated to e-cigarettes.308
While a reduction in health risks seems likely for people who smoke who completely substitute tobacco cigarettes for e-cigarettes,309,310 the benefits for those who continue to use some tobacco cigarettes are much less certain; as noted above, even ‘light’ cigarette smoking carries substantial health risks—see Section 3.36. Among those who exclusively smoke tobacco cigarettes, cutting down the number of cigarettes consumed may not reduce toxic exposure if people who smoke compensate by drawing more deeply on the cigarettes they do smoke. There is some evidence that supplementing reduced cigarette consumption with an alternative source of nicotine might reduce toxicant exposure and hence mortality among people who smoke who continue to smoke at a reduced rate.275,276,311 However, there is no available evidence whether or not long-term e-cigarette use among people who smoke changes morbidity or mortality compared with those who only smoke tobacco cigarettes.8 An analysis of PATH data in the US found that almost one-fifth of young people who used e-cigarettes maintained dual use, and this group had substantial increases in biomarkers of nicotine and tobacco toxicant exposure over time.312 Exposure to various toxicants may also vary with the patterns of use; i.e., among dual users who predominantly smoke compared with those who predominantly vape.313 Use of e-cigarettes has the potential to introduce independent or additive health risks.9,314 Targeted smoking cessation interventions for dual users have been developed with the understanding that most without such interventions will continue to smoke315—see Section 18.11.
References
1. Chapman S. Should electronic cigarettes be as freely available as tobacco cigarettes? No. British Medical Journal, 2013; 346:f3840. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23771038
2. Etter JF. Should electronic cigarettes be as freely available as tobacco? Yes. British Medical Journal, 2013; 346:f3845. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23771039
3. Kalkhoran S and Glantz SA. Modeling the Health Effects of Expanding e-Cigarette Sales in the United States and United Kingdom: A Monte Carlo Analysis. JAMA Internal Medicine, 2015; 175(10):1671-80. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26322924
4. Australian Institute of Health and Welfare. National Drug Strategy Household Survey 2022–2023. Canberra: AIHW, 2024. Available from: https://www.aihw.gov.au/reports/illicit-use-of-drugs/national-drug-strategy-household-survey
5. Rahman MA, Hann N, Wilson A, and Worrall-Carter L. Electronic cigarettes: patterns of use, health effects, use in smoking cessation and regulatory issues. Tobacco Induced Diseases, 2014; 12(1):21. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25745382
6. Osibogun O, Chapman S, Peters M, Bursac Z, and Maziak W. E-cigarette Transitions Among US Youth and Adults: Results from the Population Assessment of Tobacco and Health Study (2013-2018). J Prev (2022), 2022; 43(3):387-405. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35513733
7. Public Health England. Vaping in England: 2021 evidence update summary 2021. Available from: https://www.gov.uk/government/publications/vaping-in-england-evidence-update-february-2021/vaping-in-england-2021-evidence-update-summary
8. National Academies of Sciences Engineering and Medicine. Public health consequences of e-cigarettes. The National Academies Press, Washington, DC 2018. Available from: http://nationalacademies.org/hmd/Reports/2018/public-health-consequences-of-e-cigarettes.aspx
9. Byrne S, Brindal E, Williams G, Anastasiou K, Tonkin A, et al. E-cigarettes, smoking and health. A Literature Review Update. CSIRO, Australia, 2018. Available from: https://researchnow.flinders.edu.au/en/publications/e-cigarettes-smoking-and-health-a-literature-review-update
10. National Health and Medical Research Council. CEO statement on electronic cigarettes. 2022. Available from: https://www.nhmrc.gov.au/health-advice/all-topics/electronic-cigarettes/ceo-statement
11. SCHEER (The Scientific Committee on Health Environmental and Emerging Risks). Scientific Opinion on electronic cigarettes. 2021. Available from: https://ec.europa.eu/health/publications/electronic-cigarettes_en
12. Baenziger ON, Ford L, Yazidjoglou A, Joshy G, and Banks E. E-cigarette use and combustible tobacco cigarette smoking uptake among non-smokers, including relapse in former smokers: umbrella review, systematic review and meta-analysis. BMJ Open, 2021; 11(3):e045603. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33785493
13. Egger S, David M, Watts C, Dessaix A, Brooks A, et al. The association between vaping and subsequent initiation of cigarette smoking in young Australians from age 12 to 17 years: a retrospective cohort analysis using cross-sectional recall data from 5114 adolescents. Australian and New Zealand Journal of Public Health, 2024; 48(5):100173. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39261180
14. Conner M, Grogan S, Simms-Ellis R, Flett K, Sykes-Muskett B, et al. Evidence that an intervention weakens the relationship between adolescent electronic cigarette use and tobacco smoking: a 24-month prospective study. Tobacco Control, 2020; 29(4):425–31. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31253718
15. Epstein M, Bailey JA, Kosterman R, Rhew IC, Furlong M, et al. E-cigarette use is associated with subsequent cigarette use among young adult non-smokers, over and above a range of antecedent risk factors: a propensity score analysis. Addiction, 2021; 116(5):1224-32. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33140475
16. Hair EC, Barton AA, Perks SN, Kreslake J, Xiao H, et al. Association between e-cigarette use and future combustible cigarette use: Evidence from a prospective cohort of youth and young adults, 2017-2019. Addictive Behaviors, 2021; 112:106593. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32927247
17. Kang H and Cho SI. Longitudinal transitions of cigarettes and electronic nicotine delivery systems among adolescents: Construction of a retrospective cohort using recall data from a cross-sectional sample. Tobacco Induced Diseases, 2020; 18:92. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33192224
18. Keller-Hamilton B, Lu B, Roberts ME, Berman ML, Root ED, et al. Electronic cigarette use and risk of cigarette and smokeless tobacco initiation among adolescent boys: A propensity score matched analysis. Addictive Behaviors, 2021; 114:106770. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33316588
19. Owotomo O, Stritzel H, McCabe SE, Boyd CJ, and Maslowsky J. Smoking Intention and Progression From E-Cigarette Use to Cigarette Smoking. Pediatrics, 2020; 146(6). Available from: https://www.ncbi.nlm.nih.gov/pubmed/33168672
20. Pierce JP, Chen R, Leas EC, White MM, Kealey S, et al. Use of E-cigarettes and Other Tobacco Products and Progression to Daily Cigarette Smoking. Pediatrics, 2021; 147(2). Available from: https://www.ncbi.nlm.nih.gov/pubmed/33431589
21. Staff J, Kelly BC, Maggs JL, and Vuolo M. Adolescent electronic cigarette use and tobacco smoking in the Millennium Cohort Study. Addiction, 2022; 117(2):484-94. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34286880
22. Harlow AF, Stokes AC, Brooks DR, Benjamin EJ, Barrington-Trimis JL, et al. e-Cigarette Use and Combustible Cigarette Smoking Initiation Among Youth: Accounting for Time-Varying Exposure and Time-Dependent Confounding. Epidemiology, 2022; 33(4):523-32. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35394965
23. Loukas A, Marti CN, and Harrell MB. Electronic nicotine delivery systems use predicts transitions in cigarette smoking among young adults. Drug and Alcohol Dependence, 2022; 231:109251. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34999270
24. Xu S, Coffman DL, Liu B, Xu Y, He J, et al. Relationships Between E-cigarette Use and Subsequent Cigarette Initiation Among Adolescents in the PATH Study: an Entropy Balancing Propensity Score Analysis. Prev Sci, 2022; 23(4):608-17. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34719736
25. Melka A, Chojenta C, Holliday E, and Loxton D. E-cigarette use and cigarette smoking initiation among Australian women who have never smoked. Drug Alcohol Rev, 2021; 40(1):68-77. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32750198
26. Mongilio JM, Staff J, Seto CH, Maggs JL, and Evans-Polce RJ. Risk of adolescent cigarette use in three UK birth cohorts before and after e-cigarettes. Tobacco Control, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40730479
27. Xu S, Coffman DL, Luta G, Mai A, Jiang N, et al. Role of social-cognitive factors in the relationship between e-cigarette use and subsequent cigarette smoking among U.S. youth: A causal mediation analysis. Addictive Behaviors, 2025; 161:108204. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39520900
28. Evans-Polce RJ, Chen B, McCabe SE, and West BT. Longitudinal associations of e-cigarette use with cigarette, marijuana, and other drug use initiation among US adolescents and young adults: Findings from the population assessment of tobacco and health study (Waves 1-6). Drug and Alcohol Dependence, 2024; 263:111402. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39137612
29. O’Brien D, Long J, Lee C, McCarthy A, and Quigley J. Electronic cigarette use and tobacco cigarette smoking initiation in adolescents: An evidence review. Health Research Board, 2020. Available from: https://www.hrb.ie/fileadmin/2._Plugin_related_files/Publications/2020_publication-related_files/2020_HIE/Evidence_Centre/Electronic_cigarette_use_and_tobacco_cigarette_smoking_initiation_in_adolescents.pdf
30. Begh R, Conde M, Fanshawe TR, Kneale D, Shahab L, et al. Electronic cigarettes and subsequent cigarette smoking in young people: A systematic review. Addiction, 2025; 120(6):1090-111. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39888213
31. Kaur J, Goel S, Shabil M, Gupta S, Rana RK, et al. E-cigarette use and subsequent tobacco smoking initiation: an umbrella review with Bayesian model meta-analysis. Tobacco Control, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41748427
32. Adermark L, Galanti MR, Ryk C, Gilljam H, and Hedman L. Prospective association between use of electronic cigarettes and use of conventional cigarettes: a systematic review and meta-analysis. ERJ Open Res, 2021; 7(3). Available from: https://www.ncbi.nlm.nih.gov/pubmed/34262971
33. Chan GCK, Stjepanovic D, Lim C, Sun T, Shanmuga Anandan A, et al. Gateway or common liability? A systematic review and meta-analysis of studies of adolescent e-cigarette use and future smoking initiation. Addiction, 2021; 116(4):743-56. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32888234
34. Khouja JN, Suddell SF, Peters SE, Taylor AE, and Munafo MR. Is e-cigarette use in non-smoking young adults associated with later smoking? A systematic review and meta-analysis. Tobacco Control, 2020; 30(1):8-15. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32156694
35. O'Brien D, Long J, Quigley J, Lee C, McCarthy A, et al. Association between electronic cigarette use and tobacco cigarette smoking initiation in adolescents: a systematic review and meta-analysis. BMC Public Health, 2021; 21(1):954. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34078351
36. Zhang YY, Bu FL, Dong F, Wang JH, Zhu SJ, et al. The effect of e-cigarettes on smoking cessation and cigarette smoking initiation: An evidence-based rapid review and meta-analysis. Tobacco Induced Diseases, 2021; 19:04. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33456434
37. Yoong SL, Hall A, Turon H, Stockings E, Leonard A, et al. Association between electronic nicotine delivery systems and electronic non-nicotine delivery systems with initiation of tobacco use in individuals aged < 20 years. A systematic review and meta-analysis. PLoS One, 2021; 16(9):e0256044. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34495974
38. Asher T, Belden JL, Kelsberg G, and Safranek S. Does using e-cigarettes increase cigarette smoking in adolescents? J Fam Pract, 2019; 68(10):E12-E3. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31860706
39. Zhong J, Cao S, Gong W, Fei F, and Wang M. Electronic Cigarettes Use and Intention to Cigarette Smoking among Never-Smoking Adolescents and Young Adults: A Meta-Analysis. International Journal of Environmental Research and Public Health, 2016; 13(5). Available from: https://www.ncbi.nlm.nih.gov/pubmed/27153077
40. Parnham JC, Vrinten C, Rado MK, Bottle A, Filippidis FT, et al. Multistate transition modelling of e-cigarette use and cigarette smoking among youth in the UK. Tobacco Control, 2024; 33(4):489-96. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36898842
41. Kim S and Selya AS. The Relationship Between Electronic Cigarette Use and Conventional Cigarette Smoking Is Largely Attributable to Shared Risk Factors. Nicotine & Tobacco Research, 2020; 22(7):1123-30. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31680169
42. Green MJ, Gray L, and Sweeting H. Youth vaping and smoking and parental vaping: a panel survey. BMC Public Health, 2020; 20(1):1111. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32718309
43. Khouja JN, Wootton RE, Taylor AE, Davey Smith G, and Munafo MR. Association of genetic liability to smoking initiation with e-cigarette use in young adults: A cohort study. PLoS Med, 2021; 18(3):e1003555. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33735204
44. Shahab L, Beard E, and Brown J. Association of initial e-cigarette and other tobacco product use with subsequent cigarette smoking in adolescents: a cross-sectional, matched control study. Tobacco Control, 2021; 30(2):212-20. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32184339
45. Copp SR, Wilson MN, and Asbridge M. Smoking Susceptibility in Canadian Adolescent Electronic-Cigarette Users. Substance Use and Misuse, 2022; 57(7):1022-34. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35403553
46. Sun R, Mendez D, and Warner KE. Is Adolescent E-Cigarette Use Associated With Subsequent Smoking? A New Look. Nicotine & Tobacco Research, 2022; 24(5):710-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34897507
47. Owotomo O and Maslowsky J. Adolescent Smoking Susceptibility in the Current Tobacco Context: 2014-2016. American Journal of Health Behavior, 2018; 42(3):102-13. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29663985
48. Li S, Zeng X, Di X, and Liu S. Association between e-cigarette use and susceptibility to tobacco product use: findings from the 2019 China National Youth Tobacco Survey. Front Public Health, 2023; 11:1272680. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38288432
49. Scully M, Greenhalgh E, Bain E, Wakefield M, Durkin S, et al. E-cigarette use and other risk factors associated with tobacco smoking susceptibility among Australian adolescents. Australian and New Zealand Journal of Public Health, 2023; 47(5):100076. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37620243
50. Liu G, Wasserman E, Kong L, and Foulds J. A comparison of nicotine dependence among exclusive E-cigarette and cigarette users in the PATH study. Preventive Medicine, 2017; 104:86-91. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28389330
51. Barrington-Trimis JL, Urman R, Berhane K, Unger JB, Cruz TB, et al. E-Cigarettes and Future Cigarette Use. Pediatrics, 2016; 138(1). Available from: https://www.ncbi.nlm.nih.gov/pubmed/27296866
52. Chatterjee K, Alzghoul B, Innabi A, and Meena N. Is vaping a gateway to smoking: a review of the longitudinal studies. International Journal of Adolescent Medicine and Health, 2016; 30(3). Available from: https://www.ncbi.nlm.nih.gov/pubmed/27505084
53. Berry KM, Fetterman JL, Benjamin EJ, Bhatnagar A, Barrington-Trimis JL, et al. Association of Electronic Cigarette Use With Subsequent Initiation of Tobacco Cigarettes in US Youths. JAMA Netw Open, 2019; 2(2):e187794. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30707232
54. Chien YN, Gao W, Sanna M, Chen PL, Chen YH, et al. Electronic Cigarette Use and Smoking Initiation in Taiwan: Evidence from the First Prospective Study in Asia. International Journal of Environmental Research and Public Health, 2019; 16(7). Available from: https://www.ncbi.nlm.nih.gov/pubmed/30935027
55. Conner M, Grogan S, Simms-Ellis R, Flett K, Sykes-Muskett B, et al. Evidence that an intervention weakens the relationship between adolescent electronic cigarette use and tobacco smoking: a 24-month prospective study. Tobacco Control, 2020; 29(4):425-31. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31253718
56. McCabe SE, West BT, and McCabe VV. Associations Between Early Onset of E-cigarette Use and Cigarette Smoking and Other Substance Use Among US Adolescents: A National Study. Nicotine & Tobacco Research, 2018; 20(8):923-30. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29986103
57. Conner M, Grogan S, Simms-Ellis R, Cowap L, Armitage CJ, et al. Association between age at first reported e-cigarette use and subsequent regular e-cigarette, ever cigarette and regular cigarette use. Addiction, 2021; 116(7):1839-47. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33394523
58. Legleye S, Aubin HJ, Falissard B, Beck F, and Spilka S. Experimenting first with e-cigarettes versus first with cigarettes and transition to daily cigarette use among adolescents: the crucial effect of age at first experiment. Addiction, 2021; 116(6):1521-31. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33201553
59. Duan Z, Wang Y, and Huang J. Sex Difference in the Association between Electronic Cigarette Use and Subsequent Cigarette Smoking among U.S. Adolescents: Findings from the PATH Study Waves 1-4. International Journal of Environmental Research and Public Health, 2021; 18(4). Available from: https://www.ncbi.nlm.nih.gov/pubmed/33578770
60. Hartmann-Boyce J, Conde M, Zhitnik E, Chan J, Begh R, et al. Transitions between smoking and vaping: Evidence (or lack thereof) on potential differences by gender and sex. Preventive Medicine, 2024; 188:107974. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38677482
61. Jongenelis MI, Jardine E, Kameron C, Rudaizky D, and Pettigrew S. E-cigarette use is associated with susceptibility to tobacco use among Australian young adults. Int J Drug Policy, 2019; 74:266-73. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31257041
62. Aleyan S, Hitchman SC, Ferro MA, and Leatherdale ST. Trends and predictors of exclusive e-cigarette use, exclusive smoking and dual use among youth in Canada. Addictive Behaviors, 2020; 109:106481. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32505981
63. Kong G, Chaffee BW, Wu R, Krishnan-Sarin S, Liu F, et al. E-cigarette device type and combustible tobacco use: Results from a pooled analysis of 10,482 youth. Drug and Alcohol Dependence, 2022; 232:109279. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35063841
64. Buckner JD, Abarno CN, Zvolensky MJ, Morris PE, Walukevich-Dienst K, et al. E-cigarettes use prior to smoking combustible cigarettes among dual users: The roles of social anxiety and E-cigarette outcome expectancies. Addictive Behaviors, 2021; 117:106854. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33601094
65. Harlow AF, Han DH, Eckel SP, McConnell R, Leventhal AM, et al. The interaction of e-cigarette use and mental health symptoms on risk of cigarette smoking initiation among young adults in the United States. Addiction, 2023; 118(12):2317-26. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37620973
66. Grobman B, Wu R, Jackson A, Bold KW, Morean ME, et al. First tobacco product tried among adolescents based on race/ethnicity and socioeconomic status. Addictive Behaviors, 2021; 113:106666. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33130462
67. Stokes AC, Wilson AE, Lundberg DJ, Xie W, Berry KM, et al. Racial/Ethnic Differences in Associations of Non-cigarette Tobacco Product Use With Subsequent Initiation of Cigarettes in US Youths. Nicotine & Tobacco Research, 2021; 23(6):900-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32948872
68. Barrington-Trimis JL, Yang Z, Schiff S, Unger J, Cruz TB, et al. E-cigarette Product Characteristics and Subsequent Frequency of Cigarette Smoking. Pediatrics, 2020; 145(5). Available from: https://www.ncbi.nlm.nih.gov/pubmed/32253264
69. Kelly BC, Vuolo M, Maggs J, and Staff J. E-cigarette use among early adolescent tobacco cigarette smokers: testing the disruption and entrenchment hypotheses in two longitudinal cohorts. Tobacco Control, 2024; 33(4):497-502. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37072167
70. East K, Hitchman SC, Bakolis I, Williams S, Cheeseman H, et al. The Association Between Smoking and Electronic Cigarette Use in a Cohort of Young People. The Journal of Adolescent Health, 2018; 62(5):539-47. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29499983
71. Aleyan S, Gohari MR, Cole AG, and Leatherdale ST. Exploring the Bi-Directional Association between Tobacco and E-Cigarette Use among Youth in Canada. International Journal of Environmental Research and Public Health, 2019; 16(21). Available from: https://www.ncbi.nlm.nih.gov/pubmed/31683972
72. Chaffee BW and Cheng J. Tobacco product initiation is correlated with cross-product changes in tobacco harm perception and susceptibility: Longitudinal analysis of the Population Assessment of Tobacco and Health youth cohort. Preventive Medicine, 2018; 114:72-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29913179
73. Martinelli T, Candel M, de Vries H, Talhout R, Knapen V, et al. Exploring the gateway hypothesis of e-cigarettes and tobacco: a prospective replication study among adolescents in the Netherlands and Flanders. Tobacco Control, 2023; 32(2):170-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34226262
74. Yang Z, Berhane K, Leventhal AM, Liu M, Barrington-Trimis JL, et al. Modeling the longitudinal transitions of electronic cigarettes and conventional cigarettes with time-dependent covariates among adolescents. Preventive Medicine, 2022; 164:107294. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36216121
75. Patanavanich R, Worawattanakul M, and Glantz S. Longitudinal bidirectional association between youth electronic cigarette use and tobacco cigarette smoking initiation in Thailand. Tobacco Control, 2024; 33(3):310-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36104174
76. Hair EC, Kreslake JM, Mowery P, Pitzer L, Schillo B, et al. A longitudinal analysis of e-cigarette use and cigar, little cigar or cigarillo initiation among youth and youth adults: 2017-2019. Drug and Alcohol Dependence, 2021; 226:108821. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34218009
77. Mohammad MS, Aburezq M, AlSaeed N, Abdullah Z, Fayrouz S, et al. Electronic nicotine delivery system use and its relation to waterpipe smoking among youth in seven Arab countries. Preventive Medicine, 2024; 182:107945. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38574972
78. Nicksic NE and Barnes AJ. Is susceptibility to E-cigarettes among youth associated with tobacco and other substance use behaviors one year later? Results from the PATH study. Preventive Medicine, 2019; 121:109-14. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30776386
79. Park E, Livingston JA, Wang W, Kwon M, Eiden RD, et al. Adolescent E-cigarette use trajectories and subsequent alcohol and marijuana use. Addictive Behaviors, 2020; 103:106213. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31862618
80. Wong SW, Lohrmann DK, Middlestadt SE, and Lin HC. Is E-cigarette use a gateway to marijuana use? Longitudinal examinations of initiation, reinitiation, and persistence of e-cigarette and marijuana use. Drug and Alcohol Dependence, 2020; 208:107868. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31981994
81. Evans-Polce RJ, Patrick ME, McCabe SE, and Miech RA. Prospective associations of e-cigarette use with cigarette, alcohol, marijuana, and nonmedical prescription drug use among US adolescents. Drug and Alcohol Dependence, 2020; 216:108303. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32987363
82. Staff J, Vuolo M, Kelly BC, Maggs JL, and Silva CP. Electronic cigarette use in adolescence is associated with later cannabis use. Drug and Alcohol Dependence, 2022; 232:109302. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35038607
83. Wang Y, Duan Z, Self-Brown SR, Weaver SR, Spears CA, et al. Longitudinal associations between e-cigarette use and onset of multiple modes of cannabis use among US adolescents. Addictive Behaviors, 2022; 131:107316. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35364398
84. Westling E, Rusby JC, Crowley R, and Light JM. A Longitudinal Study of E-Cigarette, Cigarette, and Marijuana Use Sequence in Youth. Tob Use Insights, 2022; 15:1179173X221101813. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35592029
85. Temourian AA, Halliday DM, Yan Y, Chan-Golston AM, and Song AV. Marijuana and E-cigarette Initiation Among Adolescents: A Survival Analysis. The Journal of Adolescent Health, 2024; 74(4):747-54. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38085208
86. Sun R, Mendez D, and Warner KE. Use of Electronic Cigarettes Among Cannabis-Naive Adolescents and Its Association With Future Cannabis Use. JAMA Netw Open, 2022; 5(7):e2223277. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35867059
87. Silva CP, Maggs JL, Kelly BC, Vuolo M, and Staff J. Associations Between E-cigarettes and Subsequent Cocaine Use in Adolescence: An Analysis of the UK Millennium Cohort Study. Nicotine & Tobacco Research, 2023; 25(3):514-23. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36125041
88. Yimer TM, McClure-Thomas C, Stjepanovic D, Wilson J, Chan GCK, et al. The relationship between cannabis and nicotine use: A systematic review and meta-analysis. Addiction, 2024; 119(12):2076-87. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39129583
89. Perlmutter AS, Keyes KM, Giovenco D, Martins SS, and Rudolph KE. Is nicotine vaping associated with subsequent initiation of cannabis or other substances from adolescence into young adulthood? American Journal of Epidemiology, 2025; 194(5):1314-21. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38988255
90. Loukas A, Nathan Marti C, Harrell MB, Pasch KE, and Wilkinson AV. Cannabis use and associated longitudinal transitions in electronic nicotine delivery systems use among young adults in the United States. Addictive Behaviors, 2025; 160:108191. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39471779
91. Bell K and Keane H. All gates lead to smoking: The 'gateway theory', e-cigarettes and the remaking of nicotine. Social Science & Medicine, 2014; 119C:45–52. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25150650
92. Soneji S, Barrington-Trimis J, Wills T, Leventhal A, Unger J, et al. Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults: A Systematic Review and Meta-analysis. JAMA Pediatrics, 2017; 171(8):788-97. Available from: http://jamanetwork.com/journals/jamapediatrics/article-abstract/2634377
93. Dai H. Youth Observation of E-Cigarette Use in or Around School, 2019. American Journal of Preventive Medicine, 2021; 60(2):241-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33353794
94. Coleman M, Donaldson CD, Crano WD, Pike JR, and Stacy AW. Associations Between Family and Peer E-Cigarette Use With Adolescent Tobacco and Marijuana Usage: A Longitudinal Path Analytic Approach. Nicotine & Tobacco Research, 2021; 23(5):849-55. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33038257
95. Kandel ER and Kandel DB. A molecular basis for nicotine as a gateway drug. New England Journal of Medicine, 2014; 371(10):932–43. Available from: http://www.nejm.org/doi/full/10.1056/NEJMsa1405092
96. Kinnunen JM, Ollila H, Minkkinen J, Lindfors PL, Timberlake DS, et al. Nicotine matters in predicting subsequent smoking after e-cigarette experimentation: A longitudinal study among Finnish adolescents. Drug and Alcohol Dependence, 2019; 201:182-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31238240
97. Ip M and Middlekauff HR. Noncigarette Tobacco Products-Gateway or Diversion? JAMA Pediatrics, 2018; 172(8):784. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29868766
98. Hallingberg B, Maynard OM, Bauld L, Brown R, Gray L, et al. Have e-cigarettes renormalised or displaced youth smoking? Results of a segmented regression analysis of repeated cross sectional survey data in England, Scotland and Wales. Tobacco Control, 2020; 29(2):207-16. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30936390
99. Levy DT, Warner KE, Cummings KM, Hammond D, Kuo C, et al. Examining the relationship of vaping to smoking initiation among US youth and young adults: a reality check. Tobacco Control, 2019; 28(6):629-35. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30459182
100. Sokol NA and Feldman JM. High School Seniors Who Used E-Cigarettes May Have Otherwise Been Cigarette Smokers: Evidence From Monitoring the Future (United States, 2009-2018). Nicotine & Tobacco Research, 2021; 23(11):1958-61. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33991190
101. Sun T, Lim CCW, Stjepanovic D, Leung J, Connor JP, et al. Has increased youth e-cigarette use in the USA, between 2014 and 2020, changed conventional smoking behaviors, future intentions to smoke and perceived smoking harms? Addictive Behaviors, 2021; 123:107073. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34364109
102. Selya AS and Foxon F. Trends in electronic cigarette use and conventional smoking: quantifying a possible 'diversion' effect among US adolescents. Addiction, 2021; 116(7):1848-58. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33394529
103. Watkins SL, Glantz SA, and Chaffee BW. Noncigarette Tobacco Products-Gateway or Diversion?-Reply. JAMA Pediatrics, 2018; 172(8):784-5. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29868756
104. Kristjansson AL, Allegrante JP, Sigfusson J, and Sigfusdottir ID. Do population trends in adolescent electronic cigarette use coincide with changes in prevalence of cigarette smoking? Preventive Medicine Reports, 2019; 15:100913. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31211028
105. Creamer MR, Dutra LM, Sharapova SR, Gentzke AS, Delucchi KL, et al. Effects of e-cigarette use on cigarette smoking among U.S. youth, 2004-2018. Preventive Medicine, 2021; 142:106316. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33272598
106. Harrell MB, Mantey DS, Chen B, Kelder SH, and Barrington-Trimis J. Impact of the e-cigarette era on cigarette smoking among youth in the United States: A population-level study. Preventive Medicine, 2022; 164:107265. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36152819
107. Egger SJ, David M, Weber MF, Luo Q, Dessaix A, et al. Trends in adolescent smoking prevalence before and after the emergence of vaping in Australia: an interrupted time series analysis, 1999-2023. Medical Journal of Australia, 2025; 223(10):517-24. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40714936
108. Egger S, David M, McCool J, Hardie L, Weber MF, et al. Trends in smoking prevalence among 14-15-year-old adolescents before and after the emergence of vaping in New Zealand; an interrupted time series analysis of repeated cross-sectional data, 1999-2023. Lancet Reg Health West Pac, 2025; 56:101522. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40226779
109. Egger S, Waa A, David M, McCool J, Hardie L, et al. Trends in smoking prevalence before and after the emergence of vaping in Aotearoa/New Zealand among 14-15-year-olds identifying as Maori, Pacific, European, or Asian: an interrupted time series analysis of repeated cross-sectional data, 2003-2024. Lancet Reg Health West Pac, 2025; 64:101721. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41368007
110. Action on Smoking and Health. Use of vapes among young people in Great Britain. 2025. Available from: https://ash.org.uk/uploads/youth-vaping-fact-sheet-2025-final.pdf?v=1772034547
111. Beard E, Brown J, and Shahab L. Association of quarterly prevalence of e-cigarette use with ever regular smoking among young adults in England: a time-series analysis between 2007 and 2018. Addiction, 2022; 117(8):2283-93. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35263816
112. Sun R, Mendez D, and Warner KE. Association of Electronic Cigarette Use by US Adolescents With Subsequent Persistent Cigarette Smoking. JAMA Netw Open, 2023; 6(3):e234885. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36972048
113. Filippidis FT, Laverty AA, and Vardavas CI. Experimentation with e-cigarettes as a smoking cessation aid: a cross-sectional study in 28 European Union member states. BMJ Open, 2016; 6(10):e012084. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27855092
114. Gorini G, Ferrante G, Quarchioni E, Minardi V, Masocco M, et al. Electronic cigarette use as an aid to quit smoking in the representative Italian population PASSI survey. Preventive Medicine, 2017; 102:1-5. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28652088
115. McRobbie HJ, Phillips-Waller A, El Zerbi C, McNeill A, Hajek P, et al. Nicotine replacement treatment, e-cigarettes and an online behavioural intervention to reduce relapse in recent ex-smokers: a multinational four-arm RCT. Health Technology Assessment, 2020; 24(68):1-82. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33270009
116. Burrowes KS, Fuge C, Murray T, Amos J, Pitama S, et al. An evaluation of a New Zealand "vape to quit smoking" programme. New Zealand Medical Journal, 2022; 135(1561):45-55. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36049789
117. Yong HH, Gravely S, Borland R, Gartner C, Michael Cummings K, et al. Do Smokers' Perceptions of the Harmfulness of Nicotine Replacement Therapy and Nicotine Vaping Products as Compared to Cigarettes Influence Their Use as an Aid for Smoking Cessation? Findings from the ITC Four Country Smoking and Vaping Surveys. Nicotine & Tobacco Research, 2022; 24(9):1413-21. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35368082
118. Pasquereau A, Guignard R, Andler R, and Nguyen-Thanh V. Electronic cigarettes, quit attempts and smoking cessation: a 6-month follow-up. Addiction, 2017; 112(9):1620-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28504457
119. Brose LS, Hitchman SC, Brown J, West R, and McNeill A. Is the use of electronic cigarettes while smoking associated with smoking cessation attempts, cessation and reduced cigarette consumption? A survey with a 1-year follow-up. Addiction, 2015; 110(7):1160-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25900312
120. Nayak P, Pechacek TF, Weaver SR, and Eriksen MP. Electronic nicotine delivery system dual use and intention to quit smoking: Will the socioeconomic gap in smoking get greater? Addictive Behaviors, 2016; 61:112-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27268063
121. Zhuang YL, Cummins SE, Sun JY, and Zhu SH. Long-term e-cigarette use and smoking cessation: a longitudinal study with US population. Tobacco Control, 2016; 25(Suppl 1):i90-i5. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27697953
122. Brown-Johnson CG and Popova L. Exploring Smoking Stigma, Alternative Tobacco Product Use, & Quit Attempts. Health Behav Policy Rev, 2016; 3(1):13-20. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27088103
123. Christensen T, Welsh E, and Faseru B. Profile of e-cigarette use and its relationship with cigarette quit attempts and abstinence in Kansas adults. Preventive Medicine, 2014; 69:90-4. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25230365
124. Zhu SH, Zhuang YL, Wong S, Cummins SE, and Tedeschi GJ. E-cigarette use and associated changes in population smoking cessation: evidence from US current population surveys. British Medical Journal, 2017; 358:j3262. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28747333
125. Johnson L, Ma Y, Fisher SL, Ramsey AT, Chen LS, et al. E-cigarette Usage Is Associated With Increased Past-12-Month Quit Attempts and Successful Smoking Cessation in Two US Population-Based Surveys. Nicotine & Tobacco Research, 2019; 21(10):1331-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30304476
126. Airagnes G, Lemogne C, Le Faou AL, Matta J, Romanello L, et al. Do the associations between the use of electronic cigarettes and smoking reduction or cessation attempt persist after several years of use? Longitudinal analyses in smokers of the CONSTANCES cohort. Addictive Behaviors, 2021; 117:106843. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33581677
127. Jackson SE, Shahab L, West R, and Brown J. Associations between dual use of e-cigarettes and smoking cessation: A prospective study of smokers in England. Addictive Behaviors, 2020; 103:106230. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31841827
128. Han DH, Lee SH, and Seo DC. Within-Person Longitudinal Associations Between Electronic Nicotine Delivery Systems Use and Smoking Cessation Efforts Among US Continuing Adult Cigarette Smokers. Nicotine & Tobacco Research, 2022; 24(4):590-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34758071
129. Kim MM, Steffensen I, Miguel RD, Carlone J, and Curtin GM. A Systematic Review and Meta-analysis of the Association between E-cigarette Use among Cigarette Smokers and Quit Attempts Made to Abstain from Cigarette Smoking. American Journal of Health Behavior, 2022; 46(4):358-75. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36109859
130. Lee SH, Han DH, and Seo DC. Toward a better understanding of adult dual use of cigarettes and e-cigarettes based on use intensity and reasons for dual use. Addictive Behaviors, 2023; 137:107517. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36228363
131. Kasza KA, Edwards KC, Anesetti-Rothermel A, Creamer MR, Cummings KM, et al. E-cigarette use and change in plans to quit cigarette smoking among adult smokers in the United States: Longitudinal findings from the PATH Study 2014-2019. Addictive Behaviors, 2022; 124:107124. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34598012
132. Kasza KA, Hammond D, Gravely S, O'Connor RJ, Meng G, et al. Associations between nicotine vaping uptake and cigarette smoking cessation vary by smokers' plans to quit: longitudinal findings from the International Tobacco Control Four Country Smoking and Vaping Surveys. Addiction, 2023; 118(2):340-52. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36110040
133. Brown C, Nkemjika S, Yankey B, and Okosun I. Alternative Tobacco Product Use and Smoking Quit Attempts Among Teenagers in the United States: A Cross-Sectional Study. Cureus, 2021; 13(7):e16740. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34471583
134. Gallegos-Carrillo K, Barrientos-Gutierrez I, Arillo-Santillan E, Rodriguez-Bolanos R, Cruz-Jimenez L, et al. Does e-cigarette use predict short-term smoking cessation behaviors among adults who smoke in Mexico? A longitudinal study. Addictive Behaviors, 2024; 157:108077. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38851142
135. D'Mello K, Driezen P, East KA, Fong GT, and Hammond D. Trends in the use of vaping products and other smoking cessation methods among adults who attempt to stop smoking: Findings from ITC Four Country Smoking and Vaping Surveys (2016-2020). Nicotine & Tobacco Research, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40709790
136. Cole E, Segan C, Filia S, Kyi J, and Baird D. Therapeutic vapes for smoking cessation and nicotine dependence. Australian Prescriber, 2024; 47(6):171-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39777042
137. US Preventive Services Task Force. Interventions for Tobacco Smoking Cessation in Adults, Including Pregnant Persons: US Preventive Services Task Force Recommendation Statement. Journal of the American Medical Association, 2021; 425(3):265–79. Available from: https://jamanetwork.com/journals/jama/fullarticle/2775287
138. U.S. Department of Health and Human Services. Smoking Cessation. A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, 2020. Available from: https://www.hhs.gov/sites/default/files/2020-cessation-sgr-full-report.pdf
139. Banks E, Yazidjoglou A, Brown S, Nguyen M, Martin M, et al. Electronic cigarettes and health outcomes: systematic review of global evidence. Report for the Australian Department of Health, 2022, National Centre for Epidemiology and Population Health: Canberra. Available from: https://www.nhmrc.gov.au/sites/default/files/documents/attachments/ecigarettes/Electronic_cigarettes_and_health_outcomes_%20systematic_review_of_evidence.pdf.
140. Ibrahim S, Habiballah M, and Sayed IE. Efficacy of Electronic Cigarettes for Smoking Cessation: A Systematic Review and Meta-Analysis. American Journal of Health Promotion, 2021; 35(3):442-55. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33327728
141. Chan GCK, Stjepanovic D, Lim C, Sun T, Shanmuga Anandan A, et al. A systematic review of randomized controlled trials and network meta-analysis of e-cigarettes for smoking cessation. Addictive Behaviors, 2021; 119:106912. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33798919
142. Grabovac I, Oberndorfer M, Fischer J, Wiesinger W, Haider S, et al. Effectiveness of Electronic Cigarettes in Smoking Cessation: A Systematic Review and Meta-analysis. Nicotine & Tobacco Research, 2021; 23(4):625-34. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32939543
143. Pound CM, Zhang JZ, Kodua AT, and Sampson M. Smoking cessation in individuals who use vaping as compared with traditional nicotine replacement therapies: a systematic review and meta-analysis. BMJ Open, 2021; 11(2):e044222. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33619197
144. Vanderkam P, Bonneau A, Kinouani S, Dzeraviashka P, Castera P, et al. Duration of the effectiveness of nicotine electronic cigarettes on smoking cessation and reduction: Systematic review and meta-analysis. Front Psychiatry, 2022; 13:915946. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35990084
145. Li J, Hui X, Fu J, Ahmed MM, Yao L, et al. Electronic cigarettes versus nicotine-replacement therapy for smoking cessation: A systematic review and meta-analysis of randomized controlled trials. Tobacco Induced Diseases, 2022; 20:90. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36339933
146. Vyas N, Bennett A, Hamel C, Beck A, Thuku M, et al. Effectiveness of e-cigarettes as a stop smoking intervention in adults: a systematic review. Systematic Reviews, 2024; 13(1):168. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38951828
147. Wu AD, Conde M, Butler AR, Knight E, Lindson N, et al. Electronic cigarettes for smoking cessation: An overview of systematic reviews and evidence and gap map. Addiction, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41887411
148. Lindson N, Livingstone-Banks J, Butler AR, McRobbie H, Bullen CR, et al. Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews, 2025; 11(11):CD010216. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41212103
149. Lindson N, Theodoulou A, Ordonez-Mena JM, Fanshawe TR, Sutton AJ, et al. Pharmacological and electronic cigarette interventions for smoking cessation in adults: component network meta-analyses. Cochrane Database of Systematic Reviews, 2023; 9(9):CD015226. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37696529
150. Tuisku A, Rahkola M, Nieminen P, and Toljamo T. Electronic Cigarettes vs Varenicline for Smoking Cessation in Adults: A Randomized Clinical Trial. JAMA Internal Medicine, 2024; 184(8):915-21. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38884987
151. Sinha A, Wasnik M, and Chevvuri R. Electronic Cigarettes Versus Varenicline for Smoking Cessation: A Systematic Review and Meta-analysis of in-person Support Augmentation Strategies. Indian J Community Med, 2026; 51(1):21-31. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41836699
152. Wagener TL, Hinton A, Brasky TM, Cho YJ, Beebe LA, et al. E-cigarettes versus combination nicotine replacement therapy following a recent failed quit attempt: a pragmatic randomized trial through state tobacco quitlines. Lancet Reg Health Am, 2026; 54:101351. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41551921
153. Li J, Wu Q, Parrott S, Pope I, Clark LV, et al. Cost-utility analysis of provision of e-cigarette starter kits for smoking cessation in emergency departments: An economic evaluation of a randomized controlled trial. Addiction, 2025; 120(2):368-79. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39482840
154. Jimenez-Ruiz CA, Rabade-Castedo C, and de Granda-Orive JI. Electronic Cigarettes are Neither Effective Nor Safe for Quitting Smoking: A Critical View of the Most Recent Meta-Analyses. Arch Bronconeumol, 2024; 60(4):195-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38160162
155. Glantz S. New well-done RCT shows that giving smokers free e-cigarettes creates more dual users than switchers or quitters. 2023. Available from: https://profglantz.com/2023/09/22/new-well-done-rct-shows-that-giving-smokers-free-e-cigarettes-creates-more-dual-users-than-switchers-or-quitters/
156. Farber HJ. Relevant Data Missing in Electronic Cigarette vs Varenicline Trial. JAMA Internal Medicine, 2024; 184(12):1482-3. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39432274
157. Hanewinkel R, Niederberger K, Pedersen A, Unger JB, and Galimov A. E-cigarettes and nicotine abstinence: a meta-analysis of randomised controlled trials. Eur Respir Rev, 2022; 31(163). Available from: https://www.ncbi.nlm.nih.gov/pubmed/35321930
158. Wang RJ, Bhadriraju S, and Glantz SA. E-Cigarette Use and Adult Cigarette Smoking Cessation: A Meta-Analysis. American Journal of Public Health, 2021; 111(2):230-46. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33351653
159. Pluym N, Burkhardt T, Scherer G, and Scherer M. The potential of new nicotine and tobacco products as tools for people who smoke to quit combustible cigarettes - a systematic review of common practices and guidance towards a robust study protocol to measure cessation efficacy. Harm Reduct J, 2024; 21(1):130. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38970058
160. Ford A, McMillan L, Soar K, Pesola F, Notley C, et al. Exploring how an e-cigarette intervention influenced tobacco smoking behaviour in people accessing homelessness services: Findings from the SCeTCH trial process evaluation. Int J Drug Policy, 2025; 143:104901. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40616874
161. Sifat MS, Alexander AC, Businelle MS, Frank-Pearce SG, Boozary LK, et al. E-Cigarette switching and financial incentives to promote combustible cigarette cessation among adults accessing shelter services: A pilot study. Drug Alcohol Depend Rep, 2024; 13:100295. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39764385
162. Vuong JT, Ruedisueli I, Beaudin CS, and Middlekauff HR. Electronic Cigarettes: an Overlooked Tool to Alleviate Disparities in Tobacco Use Disorder Among People with Mental Health and Substance Use Disorders. Journal of General Internal Medicine, 2023; 38(8):1970-4. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36952082
163. Pratt SI, Ferron JC, Brunette MF, Santos M, Sargent J, et al. E-Cigarette Provision to Promote Switching in Cigarette Smokers With Serious Mental Illness-A Randomized Trial. Nicotine & Tobacco Research, 2022; 24(9):1405-12. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35363874
164. Smith CA, McNeill A, Kock L, Ahmed Z, and Shahab L. Mental health professionals' perceptions, judgements and decision-making practices regarding the use of electronic cigarettes as a tobacco harm reduction intervention in mental healthcare: A qualitative focus group study. Addictive Behaviors Reports, 2019; 10:100184. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31193875
165. Hickling LM, Perez-Iglesias R, McNeill A, Dawkins L, Moxham J, et al. A pre-post pilot study of electronic cigarettes to reduce smoking in people with severe mental illness. Psychological Medicine, 2019; 49(6):1033-40. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29986786
166. Royal College of Psychiatrists. The prescribing of varenicline and vaping (electronic cigarettes) to patients with severe mental illness. Royal College of Psychiatrists position statement, 2018. Available from: https://www.rcpsych.ac.uk/docs/default-source/improving-care/better-mh-policy/position-statements/ps05_18.pdf?sfvrsn=2bb7fdfe_2
167. Baggio S, Bruggmann P, Schoeni A, Abolhassani N, Tal K, et al. Efficacy of e-cigarettes for smoking cessation in populations with psychiatric and/or substance use problems: A secondary analysis of a randomized controlled trial. Tob Prev Cessat, 2025; 11. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39902147
168. Bonevski B, Rich J, Lubman DI, Segan C, Baker A, et al. Nicotine e-cigarettes for smoking cessation following discharge from smoke-free inpatient alcohol and other drug withdrawal services: a pragmatic two-arm, single-blinded, parallel-group, randomised controlled trial. Lancet Public Health, 2025; 10(7):e568-e77. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40602856
169. Pericot-Valverde I, Heo M, Nahvi S, Barron J, Voss S, et al. Effects of E-cigarettes on Combustible Cigarette Smoking Among Adults With Opioid Use Disorder on Buprenorphine: Single Arm ERASER Pilot Trial. Nicotine & Tobacco Research, 2025; 27(5):856-63. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39484988
170. Kale D, Beard E, Marshall AM, Pervin J, Wu Q, et al. Providing an e-cigarette starter kit for smoking cessation and reduction as adjunct to usual care to smokers with a mental health condition: findings from the ESCAPE feasibility study. BMC Psychiatry, 2025; 25(1):13. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39754165
171. Courtney RJ, Howard BC, Barker D, Petrie D, Borland R, et al. Vaporized Nicotine Products for Smoking Cessation Among People Experiencing Social Disadvantage : A Randomized Clinical Trial. Annals of Internal Medicine, 2025; 178(8):1085-94. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40658956
172. Thimkorn P, Booncharoen C, Chaipitak P, Wiengkeaw P, Thananithisak C, et al. Clinical effects of pharmacological and electronic cigarette interventions for smoking cessation in pregnancy: a systematic review and network meta-analysis. Addictive Behaviors, 2026; 180:108723. Available from: https://www.ncbi.nlm.nih.gov/pubmed/42048893
173. Wen X, Chung MV, Liszewski KA, Todoro LD, Giancarlo EM, et al. Cigarette Smoking Abstinence Among Pregnant Individuals Using E-Cigarettes or Nicotine Replacement Therapy. JAMA Network Open, 2023; 6(9):e2330249. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37698863
174. Przulj D, Pesola F, Myers Smith K, McRobbie H, Coleman T, et al. Helping pregnant smokers quit: a multi-centre randomised controlled trial of electronic cigarettes versus nicotine replacement therapy. Health Technology Assessment, 2023; 27(13):1-53. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37840301
175. Hajek P, Przulj D, Pesola F, Griffiths C, Walton R, et al. Electronic cigarettes versus nicotine patches for smoking cessation in pregnancy: a randomized controlled trial. Nat Med, 2022; 28(5):958-64. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35577966
176. Orton S, Taylor L, Laing L, Lewis S, Ussher M, et al. Are E-cigarettes associated with postpartum return to smoking? Secondary analyses of a UK pregnancy longitudinal cohort. BMJ Open, 2022; 12(4):e061028. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35414565
177. Innovation N, Tobacco, Research, Education, Programming, Implementation and Digital Health (INTREPID) Lab at the Centre for Addiction and Mental Health,. E-cigarette use: Evidence-informed guidance on harms and benefits. 2024. Available from: https://www.nicotinedependenceclinic.com/en/Documents/VECTOR_Guidance_Resource_FINAL.pdf
178. Royal Australian College of General Practitioners, Supporting smoking cessation: A guide for health professionals Guidance updates on smoking and vaping cessation support related to changes to Australia’s vaping regulation. Melbourne: RACGP; 2023. Available from: https://www.racgp.org.au/clinical-resources/clinical-guidelines/key-racgp-guidelines/view-all-racgp-guidelines/supporting-smoking-cessation.
179. Sharma E, Zebrak K, Lauten K, Gravely S, Cooper M, et al. Cigarette and ENDS dual use longitudinal transitions among adults in the Population Assessment of Tobacco and Health (PATH) Study, Waves 4-5 (2016-2019). Addictive Behaviors Reports, 2024; 19:100528. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38384864
180. Biener L and Hargraves JL. A longitudinal study of electronic cigarette use among a population-based sample of adult smokers: association with smoking cessation and motivation to quit. Nicotine & Tobacco Research, 2015; 17(2):127-33. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25301815
181. Delnevo CD, Giovenco DP, Steinberg MB, Villanti AC, Pearson JL, et al. Patterns of Electronic Cigarette Use Among Adults in the United States. Nicotine & Tobacco Research, 2016; 18(5):715-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26525063
182. Hitchman SC, Brose LS, Brown J, Robson D, and McNeill A. Associations Between E-Cigarette Type, Frequency of Use, and Quitting Smoking: Findings From a Longitudinal Online Panel Survey in Great Britain. Nicotine & Tobacco Research, 2015; 17(10):1187-94. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25896067
183. Giovenco DP and Delnevo CD. Prevalence of population smoking cessation by electronic cigarette use status in a national sample of recent smokers. Addictive Behaviors, 2018; 76:129-34. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28802179
184. Berry KM, Reynolds LM, Collins JM, Siegel MB, Fetterman JL, et al. E-cigarette initiation and associated changes in smoking cessation and reduction: the Population Assessment of Tobacco and Health Study, 2013-2015. Tobacco Control, 2019; 28(1):42-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29574448
185. Coleman B, Rostron B, Johnson SE, Persoskie A, Pearson J, et al. Transitions in electronic cigarette use among adults in the Population Assessment of Tobacco and Health (PATH) Study, Waves 1 and 2 (2013-2015). Tobacco Control, 2019; 28(1):50-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29695458
186. Kalkhoran S, Chang Y, and Rigotti NA. Electronic Cigarette Use and Cigarette Abstinence Over 2 Years Among U.S. Smokers in the Population Assessment of Tobacco and Health Study. Nicotine & Tobacco Research, 2020; 22(5):728-33. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31298296
187. Farsalinos KE and Niaura R. E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys. Nicotine & Tobacco Research, 2020; 22(5):655-62. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30768136
188. Glasser AM, Vojjala M, Cantrell J, Levy DT, Giovenco DP, et al. Patterns of E-cigarette Use and Subsequent Cigarette Smoking Cessation Over 2 Years (2013/2014-2015/2016) in the Population Assessment of Tobacco and Health Study. Nicotine & Tobacco Research, 2021; 23(4):669-77. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32939555
189. Harlow AF, Fetterman JL, Ross CS, Robertson RM, Bhatnagar A, et al. Association of device type, flavours and vaping behaviour with tobacco product transitions among adult electronic cigarette users in the USA. Tobacco Control, 2022; 31(e1):e10-e7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33479031
190. McDermott MS, East KA, Brose LS, McNeill A, Hitchman SC, et al. The effectiveness of using e-cigarettes for quitting smoking compared to other cessation methods among adults in the United Kingdom. Addiction, 2021; 116(10):2825-36. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33751671
191. Kasza KA, Edwards KC, Kimmel HL, Anesetti-Rothermel A, Cummings KM, et al. Association of e-Cigarette Use With Discontinuation of Cigarette Smoking Among Adult Smokers Who Were Initially Never Planning to Quit. JAMA Netw Open, 2021; 4(12):e2140880. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34962556
192. Iturralde K, Veldhuizen S, Selby P, and Zawertailo L. Concurrent E-cigarette Use While Enrolled in a Smoking Cessation Program: Associations Between Frequency of Use, Motives for Use, and Smoking Cessation. Nicotine & Tobacco Research, 2024; 26(7):888-94. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38206633
193. Wang Y, Sung HY, and Max WB. Changes in e-cigarette use and subsequent cigarette smoking cessation in the USA: evidence from a prospective PATH study, 2013-2018. Tobacco Control, 2024; 33(3):365-72. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36601780
194. Harlow AF, Stokes AC, Brooks DR, Benjamin EJ, Leventhal AM, et al. Prospective association between e-cigarette use frequency patterns and cigarette smoking abstinence among adult cigarette smokers in the United States. Addiction, 2022; 117(12):3129-39. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35913015
195. Harlow AF, Cho J, Tackett AP, McConnell RS, Leventhal AM, et al. Motivations for E-cigarette use and associations with vaping frequency and smoking abstinence among adults who smoke cigarettes in the United States. Drug and Alcohol Dependence, 2022; 238:109583. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35907310
196. Gravely S, Meng G, Hammond D, Hyland A, Michael Cummings K, et al. Differences in cigarette smoking quit attempts and cessation between adults who did and did not take up nicotine vaping: Findings from the ITC four country smoking and vaping surveys. Addictive Behaviors, 2022; 132:107339. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35605409
197. Bold K, O'Malley S, Krishnan-Sarin S, and Morean M. E-cigarette Use Patterns, Flavors, and Device Characteristics Associated With Quitting Smoking Among a U.S. sample of Adults Using E-cigarettes in a Smoking Cessation Attempt. Nicotine & Tobacco Research, 2023; 25(5):954-61. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36462196
198. Quach NE, Pierce JP, Chen J, Dang B, Stone MD, et al. Daily or Nondaily Vaping and Smoking Cessation Among Smokers. JAMA Netw Open, 2025; 8(3):e250089. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40042845
199. Coleman SRM, Bunn JY, Klemperer EM, Feinstein MJP, and Higgins ST. Electronic nicotine delivery systems (ENDS): Frequency of use and smoking-cessation efforts among U.S. women of reproductive age. Preventive Medicine, 2024; 188:108020. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38821421
200. Gravely S, Yong HH, Reid JL, East KA, Gartner CE, et al. Do Current Smokers and Ex-Smokers Who Use Nicotine Vaping Products Daily Versus Weekly Differ on Their Reasons for Vaping? Findings from the 2020 ITC Four Country Smoking and Vaping Survey. International Journal of Environmental Research and Public Health, 2022; 19(21). Available from: https://www.ncbi.nlm.nih.gov/pubmed/36361015
201. Liber AC, Knoll M, Cadham CJ, Issabakhsh M, Oh H, et al. The role of flavored electronic nicotine delivery systems in smoking cessation: A systematic review. Drug Alcohol Depend Rep, 2023; 7:100143. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37012981
202. Lindson N, Butler AR, Liber A, Levy DT, Barnett P, et al. An exploration of flavours in studies of e-cigarettes for smoking cessation: secondary analyses of a systematic review with meta-analyses. Addiction, 2023; 118(4):634-45. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36399154
203. Lindson N, Livingstone-Banks J, Butler AR, Levy DT, Barnett P, et al. An update of a systematic review and meta-analyses exploring flavours in intervention studies of e-cigarettes for smoking cessation. Addiction, 2025; 120(4):770-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39702981
204. Kasza KA, Tang Z, Benson AF, Creamer MR, Edwards KC, et al. Trends in cigarette discontinuation rates in the U.S. across 2014/15-2021 among adults who use electronic nicotine delivery systems (ENDS): Trends by ENDS flavor, ENDS device type, and age group from the PATH Study. Nicotine & Tobacco Research, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41105127
205. Sharma E, Yang DH, and Stroud LR. Variations in Electronic Nicotine Delivery System (ENDS) device types and association with cigarette quit attempts. Preventive Medicine, 2021; 148:106588. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33930433
206. Gravely S, Yong HH, Reid JL, East KA, Liber AC, et al. An examination of quitting smoking as a reason for vaping by the type of nicotine vaping device used most often among adults who smoke and vape: Findings from the Canada, England and the United States 2020 ITC Smoking and Vaping Survey. Preventive Medicine Reports, 2023; 33:102201. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37223550
207. Cho YJ, Hinton A, Nshimiyimana J, Mehta T, Queimado L, et al. The effect of higher versus lower wattage e-cigarettes on smoking: A randomized controlled trial. Addiction, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/42167788
208. Rose JE, Behm FM, Willette PN, Botts TL, and Botts DR. Using varenicline in combination with electronic nicotine delivery systems (ENDS). Drug and Alcohol Dependence, 2023; 251:110916. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37611481
209. Tattan-Birch H, Kock L, Brown J, Beard E, Bauld L, et al. E-cigarettes to Augment Stop Smoking In-person Support and Treatment With Varenicline (E-ASSIST): A Pragmatic Randomized Controlled Trial. Nicotine & Tobacco Research, 2023; 25(3):395-403. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35738868
210. Rose JE, Willette PN, Botts TL, Botts DR, and Behm FM. Bupropion/zonisamide combination to assist smokers to switch from combustible cigarettes to electronic nicotine delivery systems (ENDS). Drug and Alcohol Dependence, 2022; 234:109346. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35306393
211. Jackson SE, Kotz D, West R, and Brown J. Moderators of real-world effectiveness of smoking cessation aids: a population study. Addiction, 2019; 114(9):1627-38. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31117151
212. Gomajee R, El-Khoury F, Goldberg M, Zins M, Lemogne C, et al. Association Between Electronic Cigarette Use and Smoking Reduction in France. JAMA Internal Medicine, 2019; 179(9):1193-200. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31305860
213. Beard E, West R, Michie S, and Brown J. Association of prevalence of electronic cigarette use with smoking cessation and cigarette consumption in England: a time-series analysis between 2006 and 2017. Addiction, 2020; 115(5):961-74. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31621131
214. Kalkhoran S, Chang Y, and Rigotti NA. E-cigarettes and Smoking Cessation in Smokers With Chronic Conditions. American Journal of Preventive Medicine, 2019; 57(6):786-91. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31753259
215. Hedman L, Galanti MR, Ryk L, Gilljam H, and Adermark L. Electronic cigarette use and smoking cessation in cohort studies and randomized trials: A systematic review and meta-analysis. Tob Prev Cessat, 2021; 7:62. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34712864
216. Simonavicius E, McNeill A, and Brose LS. Transitions in smoking and nicotine use from 2016 to 2017 among a UK cohort of adult smokers and ex-smokers. Drug Alcohol Rev, 2020; 39(7):994-1005. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32458503
217. Jackson SE, Brown J, and Beard E. Associations of Prevalence of E-cigarette Use With Quit Attempts, Quit Success, Use of Smoking Cessation Medication, and the Overall Quit Rate Among Smokers in England: A Time-Series Analysis of Population Trends 2007-2022. Nicotine & Tobacco Research, 2024; 26(7):826-34. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38214664
218. Jackson SE, Brown J, Buss V, and Shahab L. Prevalence of Popular Smoking Cessation Aids in England and Associations With Quit Success. JAMA Netw Open, 2025; 8(1):e2454962. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39821398
219. Jackson SE, Brown J, Shahab L, and Cox S. Use, perceptions, and effectiveness of e-cigarettes for smoking cessation among older adults in England: a population study, 2014-2024. BMC Medicine, 2024; 22(1):500. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39482655
220. Buss VH, Beard E, Shahab L, Simonavicius E, Bauld L, et al. Associations between the national 'Swap to Stop' programme offering free vapes for smoking cessation and quit attempts in England: Results from a population-based survey. Addiction, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41785407
221. Chambers MS. Effect of vaping on past-year smoking cessation success of Australians in 2019-evidence from a national survey. Addiction, 2022; 117(8):2306-15. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35403757
222. Sun T, Lim CCW, Rutherford BN, Johnson B, Leung J, et al. Is smoking reduction and cessation associated with increased e-cigarette use? Findings from a nationally representative sample of adult smokers in Australia. Addictive Behaviors, 2022; 127:107217. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34954648
223. Nip J, Zhang J, Stanley J, Waa A, Ball J, et al. Patterns and experiences of smoking, electronic cigarettes (vapes) and heated tobacco use among people who smoke or who recently quit. New Zealand Medical Journal, 2025; 138(1612):21-46. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40146955
224. Foxon F and Niaura R. Use of nicotine products, prescription drug products, and other methods to stop smoking by US adults in the 2022 National Health Interview Survey. Intern Emerg Med, 2025; 20(3):691-700. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39760947
225. Kotz D, Jackson S, Brown J, and Kastaun S. The Effectiveness of E-Cigarettes for Smoking Cessation. Dtsch Arztebl Int, 2022; 119(17):297-301. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35384835
226. Fekom M, Aarbaoui TE, Guignard R, Andler R, Quatremere G, et al. Use of tobacco cessation aids and likelihood of smoking cessation: A French population-based study. Preventive Medicine Reports, 2022; 30:102044. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36531094
227. Farsalinos KE and Barbouni A. Association between electronic cigarette use and smoking cessation in the European Union in 2017: analysis of a representative sample of 13 057 Europeans from 28 countries. Tobacco Control, 2021; 30(1):71-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32015151
228. Gorini G, Carreras G, Lugo A, Gallus S, Masocco M, et al. Electronic cigarette use as an aid to quit smoking: Evidence from PASSI survey, 2014-2021. Preventive Medicine, 2023; 166:107391. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36529403
229. Brennan MM, Bowe AK, Sheridan A, Doyle F, Boland F, et al. Evolution of nicotine product use in Ireland 2015-2023, and associations with quit intentions and attempts: an analysis of nationally representative repeated cross-sectional surveys. Lancet Reg Health Eur, 2025; 55:101352. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40678043
230. Chen R, Pierce JP, Leas EC, White MM, Kealey S, et al. Use of Electronic Cigarettes to Aid Long-Term Smoking Cessation in the United States: Prospective Evidence From the PATH Cohort Study. American Journal of Epidemiology, 2020; 189(12):1529-37. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32715314
231. Pierce JP, Benmarhnia T, Chen R, White M, Abrams DB, et al. Role of e-cigarettes and pharmacotherapy during attempts to quit cigarette smoking: The PATH Study 2013-16. PLoS One, 2020; 15(9):e0237938. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32877429
232. Chen R, Pierce JP, Leas EC, Benmarhnia T, Strong DR, et al. Effectiveness of e-cigarettes as aids for smoking cessation: evidence from the PATH Study cohort, 2017-2019. Tobacco Control, 2023; 32(e2):e145-e52. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35131948
233. Osibogun O, Bursac Z, and Maziak W. Longitudinal transition outcomes among adult dual users of e-cigarettes and cigarettes with the intention to quit in the United States: PATH Study (2013-2018). Preventive Medicine Reports, 2022; 26:101750. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35256929
234. Kaplan B, Galiatsatos P, Breland A, Eissenberg T, and Cohen JE. Effectiveness of ENDS, NRT and medication for smoking cessation among cigarette-only users: a longitudinal analysis of PATH Study wave 3 (2015-2016) and 4 (2016-2017), adult data. Tobacco Control, 2023; 32(3):302-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34526410
235. Kwon E, Choe S, Williamson J, and Seo DC. E-Cigarette Use and Long-Term Cigarette Smoking Cessation Among U.S. Adult Cigarette Smokers. Substance Use and Misuse, 2025:1-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41175029
236. Kasza KA, Tang Z, Seo YS, Benson AF, Creamer MR, et al. Divergence in Cigarette Discontinuation Rates by Use of Electronic Nicotine Delivery Systems (ENDS): Longitudinal Findings From the United States PATH Study Waves 1-6. Nicotine & Tobacco Research, 2025; 27(2):236-43. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38566367
237. Kasza KA, Rivard C, Goniewicz ML, Fong GT, Hammond D, et al. E-Cigarette Characteristics and Cigarette Cessation Among Adults Who Use E-Cigarettes. JAMA Netw Open, 2024; 7(8):e2423960. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39088219
238. Erinoso O, Kasza K, Hyland A, and Pearson J. Estimating the likelihood of cigarette maintenance and dual use among people using e-cigarettes for cigarette cessation: Analysis of the Population Assessment of Tobacco and Health Study Waves 5 and 6. Addictive Behaviors, 2025; 171:108458. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40884899
239. Erinoso O, Osibogun O, Li W, and Kalan ME. Longitudinal examination of ENDS characteristics, flavors, and nicotine content for cigarette cessation: Findings from PATH waves 5-6. Addictive Behaviors, 2024; 157:108097. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38943930
240. Cho J, Han DH, Harlow AF, Dai HD, and Leventhal AM. Association of Naturalistic E-Cigarette Use and Smoking Cessation in U.S. Adults. American Journal of Epidemiology, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41347854
241. Xu S, Zhu J, Zhang Y, Hill J, Feng Y, et al. Effectiveness of nicotine vape products (E-cigarettes) as a smoking cessation aid for US adults: a narrative review of findings from the population assessment of tobacco and health study. Nicotine & Tobacco Research, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/42056841
242. Mason A, Riordan BC, Winter T, Conner TS, Sibley CG, et al. Effects of vaping on uptake and cessation of smoking: Longitudinal analysis in Aotearoa New Zealand adults. Drug Alcohol Rev, 2023; 42(6):1587-94. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37368846
243. Kaplan B, Tseng TY, Hardesty JJ, Czaplicki L, and Cohen JE. Beneficial and Harmful Tobacco-Use Transitions Associated With ENDS in the U.S. American Journal of Preventive Medicine, 2025; 68(5):896-904. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39880060
244. Lin LY, Chien YN, Chen YH, Shean R, Wu CY, et al. E-cigarettes and smoking cessation among adolescent smokers. Scientific Reports, 2022; 12(1):19489. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36376363
245. Glantz SA. e-Cigarettes Used by Adolescents to Try to Quit Smoking Are Associated With Less Quitting: A Cross-Sectional Analysis of the National Youth Tobacco Survey. The Journal of Adolescent Health, 2023; 72(3):359-64. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36476393
246. Butler AR, Lindson N, Fanshawe TR, Theodoulou A, Begh R, et al. Longer-term use of electronic cigarettes when provided as a stop smoking aid: Systematic review with meta-analyses. Preventive Medicine, 2022; 165(Pt B):107182. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35933001
247. Jackson SE, Brown J, Kock L, and Shahab L. Prevalence and uptake of vaping among people who have quit smoking: a population study in England, 2013-2024. BMC Medicine, 2024; 22(1):503. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39567975
248. Gravely S, Meng G, Cummings KM, Hyland A, Borland R, et al. Changes in Smoking and Vaping over 18 Months among Smokers and Recent Ex-Smokers: Longitudinal Findings from the 2016 and 2018 ITC Four Country Smoking and Vaping Surveys. International Journal of Environmental Research and Public Health, 2020; 17(19). Available from: https://www.ncbi.nlm.nih.gov/pubmed/32992667
249. Hajek P, Przulj D, Myers Smith K, Li J, Sasieni P, et al. Continuing use of e-cigarettes after stopping smoking and relapse: Secondary analysis of a large randomised controlled trial. Addiction, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41560608
250. Dai H and Leventhal AM. Association of electronic cigarette vaping and subsequent smoking relapse among former smokers. Drug and Alcohol Dependence, 2019; 199:10-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30978519
251. McMillen R, Klein JD, Wilson K, Winickoff JP, and Tanski S. E-Cigarette Use and Future Cigarette Initiation Among Never Smokers and Relapse Among Former Smokers in the PATH Study. Public Health Rep, 2019; 134(5):528-36. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31419184
252. Everard CD, Silveira ML, Kimmel HL, Marshall D, Blanco C, et al. Association of Electronic Nicotine Delivery System Use With Cigarette Smoking Relapse Among Former Smokers in the United States. JAMA Netw Open, 2020; 3(6):e204813. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32501492
253. Azagba S, Qeadan F, Shan L, Latham K, and Wolfson M. E-Cigarette Use and Transition in Adult Smoking Frequency: A Longitudinal Study. American Journal of Preventive Medicine, 2020; 59(3):367-76. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32684358
254. Brouwer AF, Jeon J, Hirschtick JL, Jimenez-Mendoza E, Mistry R, et al. Transitions between cigarette, ENDS and dual use in adults in the PATH study (waves 1-4): multistate transition modelling accounting for complex survey design. Tobacco Control, 2020. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33199541
255. Pierce JP, Chen R, Kealey S, Leas EC, White MM, et al. Incidence of Cigarette Smoking Relapse Among Individuals Who Switched to e-Cigarettes or Other Tobacco Products. JAMA Netw Open, 2021; 4(10):e2128810. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34665239
256. Ozga JE, Jensen JK, Chen-Sankey J, Perez A, and Stanton CA. New versus continued e-cigarette use and cigarette reuptake among US adults who formerly smoked cigarettes. Addictive Behaviors, 2026; 178:108677. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41880794
257. Hardie I and Green MJ. Vaping and socioeconomic inequalities in smoking cessation and relapse: a longitudinal analysis of the UK Household Longitudinal Study. Tobacco Control, 2024; 33(e2):e165-e72. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37041075
258. Brose LS, Bowen J, McNeill A, and Partos TR. Associations between vaping and relapse to smoking: preliminary findings from a longitudinal survey in the UK. Harm Reduct J, 2019; 16(1):76. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31888637
259. Barufaldi LA, Guerra RL, de Albuquerque RCR, Nascimento A, Chanca RD, et al. Risk of smoking relapse with the use of electronic cigarettes: A systematic review with meta-analysis of longitudinal studies. Tob Prev Cessat, 2021; 29:29. Available from: https://www.ncbi.nlm.nih.gov/pubmed/33928198
260. Kim MM, Steffensen I, Miguel RTD, Babic T, and Carlone J. A Systematic Review Investigating Associations Between E-Cigarette Use Among Former Cigarette Smokers and Relapse to Smoking Cigarettes. Inquiry, 2023; 60:469580231214457. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38031340
261. Hartmann-Boyce J, Chan J, Zhitnik E, Pesola F, Hajek P, et al. Longitudinal Patterns in Smoking Abstinence in Trials of E-cigarettes for Smoking Cessation: Secondary Analysis of Data From a Systematic Review, With Meta-Analyses. Nicotine & Tobacco Research, 2025; 27(8):1486-91. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39756408
262. Sun R, Mendez D, and Warner KE. Cigarette Smoking Relapse Among People Who Switched to E-cigarettes or Other Tobacco Products. Nicotine & Tobacco Research, 2025; 27(4):637-43. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39231538
263. Klemperer EM, Bunn JY, Palmer AM, Smith TT, Toll BA, et al. E-cigarette cessation and transitions in combusted tobacco smoking status: longitudinal findings from the US FDA PATH Study. Addiction, 2023; 118(6):1161-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36710461
264. Graham AL, Cha S, Papandonatos GD, Amato MS, Jacobs MA, et al. E-cigarette and combusted tobacco abstinence among young adults: Secondary analyses from a U.S.-based randomized controlled trial of vaping cessation. Preventive Medicine, 2022; 165(Pt B):107119. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35777699
265. Bullen C, Howe C, Laugesen M, McRobbie H, Parag V, et al. Electronic cigarettes for smoking cessation: a randomised controlled trial. Lancet, 2013; 382(9905):1629-37. Available from: https://www.ncbi.nlm.nih.gov/pubmed/24029165
266. Adkison SE, O'Connor RJ, Bansal-Travers M, Hyland A, Borland R, et al. Electronic nicotine delivery systems: international tobacco control four-country survey. American Journal of Preventive Medicine, 2013; 44(3):207-15. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23415116
267. Martinez U, Martinez-Loredo V, Simmons VN, Meltzer LR, Drobes DJ, et al. How Does Smoking and Nicotine Dependence Change After Onset of Vaping? A Retrospective Analysis of Dual Users. Nicotine & Tobacco Research, 2020; 22(5):764-70. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30883640
268. Piper ME, Schlam TR, Donny EC, Kobinsky K, Matthews J, et al. The Impact of Three Alternate Nicotine-Delivery Products on Combusted Cigarette Use: A Randomized Controlled Trial. Nicotine & Tobacco Research, 2025; 27(2):317-25. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38348917
269. Rose JE, Frisbee S, Campbell D, Salley A, Claerhout S, et al. Smoking reduction using electronic nicotine delivery systems in combination with nicotine skin patches. Psychopharmacology (Berl), 2023; 240(9):1901-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/37458789
270. McRobbie H, Bullen C, Hartmann-Boyce J, and Hajek P. Electronic cigarettes for smoking cessation and reduction. Cochrane Database of Systematic Reviews, 2014; 12(12):CD010216. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25515689
271. Rahman MA, Hann N, Wilson A, Mnatzaganian G, and Worrall-Carter L. E-cigarettes and smoking cessation: evidence from a systematic review and meta-analysis. PLoS One, 2015; 10(3):e0122544. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25822251
272. Avila JC, Maglalang DD, Nollen NL, Lee SC, Suh R, et al. Using Pod Based e-Cigarettes and Nicotine Pouches to Reduce Harm for Adults With Low Socioeconomic Status Who Smoke: A Pilot Randomized Controlled Trial. Nicotine & Tobacco Research, 2024; 26(9):1150-8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38447095
273. Kim S, Goldenson NI, Selya A, and Shiffman S. Switching Away From Smoking and Reduction in Cigarette Consumption Among U.S. Adult Purchasers of the JUUL System Across 24 Months Including Diverse Subpopulations Disproportionately Affected by Cigarette Smoking. Nicotine & Tobacco Research, 2024; 26(9):1183-91. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38553983
274. Rostron BL, Corey CG, Chang JT, van Bemmel DM, Miller ME, et al. Changes in cigarettes per day and biomarkers of exposure among US adult smokers in the Population Assessment of Tobacco and Health Study waves 1 and 2 (2013-2015). Nicotine & Tobacco Research, 2020; 22(10):1780–7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32221599
275. Hart C, Gruer L, and Bauld L. Does smoking reduction in midlife reduce mortality risk? Results of 2 long-term prospective cohort studies of men and women in Scotland. American Journal of Epidemiology, 2013; 178(5):770–9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23825165
276. Tverdal A and Bjartveit K. Health consequences of reduced daily cigarette consumption. Tobacco Control, 2006; 15(6):472–80. Available from: https://www.ncbi.nlm.nih.gov/pubmed/17130377
277. Bjartveit K and Tverdal A. Health consequences of smoking 1-4 cigarettes per day. Tobacco Control, 2005; 14(5):315-20. Available from: https://www.ncbi.nlm.nih.gov/pubmed/16183982
278. Dalack GW and Meador-Woodruff JH. Acute feasibility and safety of a smoking reduction strategy for smokers with schizophrenia. Nicotine & Tobacco Research, 1999; 1(1):53-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/11072388
279. Bolliger CT, Zellweger JP, Danielsson T, van Biljon X, Robidou A, et al. Smoking reduction with oral nicotine inhalers: double blind, randomised clinical trial of efficacy and safety. British Medical Journal, 2000; 321(7257):329–33. Available from: https://www.ncbi.nlm.nih.gov/pubmed/10926587
280. Fagerstrom KO, Tejding R, Westin A, and Lunell E. Aiding reduction of smoking with nicotine replacement medications: hope for the recalcitrant smoker? Tobacco Control, 1997; 6(4):311-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/9583629
281. Bittoun R, Barone M, Mendelsohn CP, Elcombe EL, and Glozier N. Promoting positive attitudes of tobacco-dependent mental health patients towards NRT-supported harm reduction and smoking cessation. Australian and New Zealand Journal of Psychiatry, 2014; 48(10):954–6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/24907132
282. Cohen B, Harm reduction in substance use: smoking cessation for marginalised populations. Bayside Medicare Local; 2014. Available from: http://bml.org.au/BML%20Smoking%20Cessation%20in%20Marginalised%20Populations.pdf.
283. McNeill A. Harm reduction. Review. British Medical Journal, 2004; 328(7444):885–7. Available from: http://www.bmj.com/cgi/content/full/328/7444/885
284. Wang D, Connock M, Barton P, Fry-Smith A, Aveyard P, et al. 'Cut down to quit' with nicotine replacement therapies in smoking cessation: a systematic review of effectiveness and economic analysis. Health Technology Assessment, 2008; 12(2):iii-iv, ix-xi, 1-135. Available from: https://www.ncbi.nlm.nih.gov/pubmed/18093448
285. Begh R, Lindson-Hawley N, and Aveyard P. Does reduced smoking if you can't stop make any difference? BMC Medicine, 2015; 13:257. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26456865
286. Lindson N, Klemperer E, Hong B, Ordonez-Mena JM, and Aveyard P. Smoking reduction interventions for smoking cessation. Cochrane Database of Systematic Reviews, 2019; 9(9):CD013183. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31565800
287. Moore D, Aveyard P, Connock M, Wang D, Fry-Smith A, et al. Effectiveness and safety of nicotine replacement therapy assisted reduction to stop smoking: systematic review and meta-analysis. British Medical Journal, 2009; 338(b1024):b1024. Available from: https://www.ncbi.nlm.nih.gov/pubmed/19342408
288. Stead LF and Lancaster T. Interventions to reduce harm from continued tobacco use. Cochrane Database of Systematic Reviews, 2007; (3):CD005231. Available from: https://www.ncbi.nlm.nih.gov/pubmed/17636791
289. Skelton E, Lum A, Robinson M, Dunlop A, Guillaumier A, et al. A pilot randomised controlled trial of abrupt versus gradual smoking cessation in combination with vaporised nicotine products for people receiving alcohol and other drug treatment. Addictive Behaviors, 2022; 131:107328. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35405479
290. Zhu SH, Sun JY, Bonnevie E, Cummins SE, Gamst A, et al. Four hundred and sixty brands of e-cigarettes and counting: implications for product regulation. Tobacco Control, 2014; 23 Suppl 3:iii3–9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/24935895
291. Robertson L, Hoek J, Blank ML, Richards R, Ling P, et al. Dual use of electronic nicotine delivery systems (ENDS) and smoked tobacco: a qualitative analysis. Tobacco Control, 2019; 28(1):13-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29419488
292. Glasser AM, Collins L, Pearson JL, Abudayyeh H, Niaura RS, et al. Overview of Electronic Nicotine Delivery Systems: A Systematic Review. American Journal of Preventive Medicine, 2017; 52(2):e33-e66. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27914771
293. Simonavicius E, McNeill A, Arnott D, and Brose LS. What factors are associated with current smokers using or stopping e-cigarette use? Drug and Alcohol Dependence, 2017; 173:139-43. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28246049
294. Owusu D, Huang J, Weaver SR, Pechacek TF, Ashley DL, et al. Patterns and trends of dual use of e-cigarettes and cigarettes among U.S. adults, 2015-2018. Preventive Medicine Reports, 2019; 16:101009. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31763161
295. Osibogun O, Bursac Z, McKee M, Li T, and Maziak W. Cessation outcomes in adult dual users of e-cigarettes and cigarettes: the Population Assessment of Tobacco and Health cohort study, USA, 2013-2016. International Journal of Public Health, 2020; 65(6):923-36. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32710136
296. Abi Nehme AM, Lou X, Yan X, Lee JH, and Salloum RG. Transition to smoking cessation among dual cigarette and e-cigarette users in the population assessment of tobacco and health study, Waves 3 and 4 (2015-2017). Addictive Behaviors, 2022; 129:107284. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35217415
297. Hamoud J, Hanewinkel R, Andreas S, Ammous O, Saalfrank M, et al. A systematic review investigating the impact of dual use of e-cigarettes and conventional cigarettes on smoking cessation. ERJ Open Res, 2025; 11(3). Available from: https://www.ncbi.nlm.nih.gov/pubmed/40337339
298. Evans-Polce RJ, Mongilio JM, Kcomt L, Chen B, and McCabe SE. Trends and Sociodemographic Differences in Tobacco/Nicotine Transitions Among U.S. Adolescents and Young Adults Using e-cigarettes, 2014-2023. The Journal of Adolescent Health, 2025; 76(5):920-7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39969469
299. Thao Tran TP, Pechacek TF, Ashley DL, Spears CA, Kute NG, et al. Transitions and patterns in concurrent use of cigarettes and electronic cigarettes: An intensive longitudinal study of adults who smoke cigarettes and recently initiated e-cigarette use. Addictive Behaviors, 2025; 171:108474. Available from: https://www.ncbi.nlm.nih.gov/pubmed/40907174
300. Jackson SE, Cox S, Shahab L, and Brown J. Trends and patterns of dual use of combustible tobacco and e-cigarettes among adults in England: A population study, 2016-2024. Addiction, 2025; 120(4):608-19. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39842468
301. Pesola F, Myers Smith K, Przulj D, Ladmore D, Phillips-Waller A, et al. Patterns of e-Cigarette Use and Smoking Cessation Outcomes: Secondary Analysis of a Large Randomised Controlled Trial to Inform Clinical Advice. Nicotine & Tobacco Research, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41368708
302. Baig SA and Giovenco DP. Behavioral heterogeneity among cigarette and e-cigarette dual-users and associations with future tobacco use: Findings from the Population Assessment of Tobacco and Health Study. Addictive Behaviors, 2020; 104:106263. Available from: https://www.ncbi.nlm.nih.gov/pubmed/32028096
303. Shafie-Khorassani F, Piper ME, Jorenby DE, Baker TB, Benowitz NL, et al. Associations of Demographics, Dependence, and Biomarkers With Transitions in Tobacco Product Use in a Cohort of Cigarette Users and Dual Users of Cigarettes and E-cigarettes. Nicotine & Tobacco Research, 2023; 25(3):462-9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36037523
304. Krishnan N, Berg CJ, Elmi AF, Klemperer EM, Sherman SE, et al. Trajectories of ENDS and cigarette use among dual users: analysis of waves 1 to 5 of the PATH Study. Tobacco Control, 2024; 33(e1):e62-e8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36601793
305. Gallegos-Carrillo K, Barrientos-Gutierrez I, Arillo-Santillan E, Rodriguez-Bolanos R, Cruz-Jimenez L, et al. Transitions between tobacco products: Correlates of changes in cigarette smoking and e-cigarette use among exclusive adult smokers and dual users in Mexico. Preventive Medicine Reports, 2022; 29:101869. Available from: https://www.ncbi.nlm.nih.gov/pubmed/35911576
306. Brouwer AF, Roberts OK, Jeon J, Jimenez-Mendoza E, Land SR, et al. Transitions in cigarette and ENDS use in the PATH Study: a multistate transition model analysis of adults in 2021-2022 compared to previous years. medRxiv, 2025. Available from: https://www.ncbi.nlm.nih.gov/pubmed/41445640
307. Brouwer AF, Jeon J, Jimenez-Mendoza E, Land SR, Holford TR, et al. Changing patterns of cigarette and ENDS transitions in the USA: a multistate transition analysis of adults in the PATH Study in 2017-2019 vs 2019-2021. Tobacco Control, 2024. Available from: https://www.ncbi.nlm.nih.gov/pubmed/39174323
308. Hanewinkel R and Glantz SA. Clinical trial shows that giving smokers free e-cigarettes creates more dual users than switchers or quitters. EClinicalMedicine, 2024; 68:102452. Available from: https://www.ncbi.nlm.nih.gov/pubmed/38333538
309. Farsalinos KE and Polosa R. Safety evaluation and risk assessment of electronic cigarettes as tobacco cigarette substitutes: a systematic review. Ther Adv Drug Saf, 2014; 5(2):67-86. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25083263
310. Oh AY and Kacker A. Do electronic cigarettes impart a lower potential disease burden than conventional tobacco cigarettes? Review on E-cigarette vapor versus tobacco smoke. Laryngoscope, 2014; 124(12):2702-6. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25302452
311. Chapman S. E-cigarettes: the best and the worst case scenarios for public health-an essay by Simon Chapman. British Medical Journal, 2014; 349:g5512. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25204397
312. Evans-Polce RJ, Lim C, Smith DM, and Mongilio JM. Nicotine and tobacco transitions among US youth using electronic nicotine delivery systems (ENDS): Associations with frequency, nicotine dependence, and biomarkers of exposure. Nicotine & Tobacco Research, 2026. Available from: https://www.ncbi.nlm.nih.gov/pubmed/42149979
313. Coleman SRM, Piper ME, Byron MJ, and Bold KW. Dual Use of Combustible Cigarettes and E-cigarettes: a Narrative Review of Current Evidence. Curr Addict Rep, 2022; 9(4):353-62. Available from: https://www.ncbi.nlm.nih.gov/pubmed/36467719
314. Wang JB, Olgin JE, Nah G, Vittinghoff E, Cataldo JK, et al. Cigarette and e-cigarette dual use and risk of cardiopulmonary symptoms in the Health eHeart Study. PLoS One, 2018; 13(7):e0198681. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30044773
315. Martinez U, Simmons VN, Sutton SK, Drobes DJ, Meltzer LR, et al. Targeted smoking cessation for dual users of combustible and electronic cigarettes: a randomised controlled trial. Lancet Public Health, 2021; 6(7):e500-e9. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34175001