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7.16 Pharmacotherapies for smoking cessation
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Greenhalgh, EM|Dean, E|Stillman, S|Ford, C. 7.16 Pharmacotherapies for smoking cessation. In Greenhalgh, EM|Scollo, MM|Winstanley, MH [editors]. Tobacco in Australia: Facts and issues. Melbourne : Cancer Council Victoria; 2019. Available from https://www.tobaccoinaustralia.org.au/chapter-7-cessation/7-16-pharmacotherapy
Last updated: July 2026

7.16 Pharmacotherapies for smoking cessation

Note: This section is intended for health professionals. People who smoke tobacco and are interested in quitting can find information at: https://www.quit.org.au/ 

7.16.0 Introduction

The development and introduction of pharmacotherapies has provided much-needed assistance for people who smoke and are trying to quit, particularly for those who are more nicotine dependent. Pharmacotherapies for cessation primarily aim to reduce withdrawal symptoms and block the reinforcing effects of nicotine. A substantial body of research has demonstrated the effectiveness of such therapies for increasing smoking abstinence rates. In 2020, the US Surgeon General concluded that cessation medications are independently effective in increasing smoking cessation, and are more effective than self-help materials or no treatment.1 First-line treatments are those that have been shown to be effective and safe and are licensed for smoking cessation in Australia. These include nicotine replacement therapy (NRT), especially patches combined with fast-acting forms (i.e. combination NRT), bupropion, and varenicline, all of which increase smoking cessation. Recent research has also supported the use of cytisine for smoking cessation,2 and in 2024 the Therapeutic Goods Administration (TGA) made a final decision to make cytisine available in Australia.3 Varenicline has generally been shown to be superior to bupropion and single forms of NRT, but similarly effective as cytisine and combination NRT (i.e., faster-acting plus longer-acting form).

Figure 7.16.1 shows the findings of recent Cochrane reviews examining the effectiveness of NRT,4,5 bupropion,6 varenicline,7 cytisine,7 and combinations of these medications.6 Confidence intervals that cross 1 indicate no difference in effectiveness between the medications; though the authors of the review6 examining bupropion combined with varenicline suggest that the findings point to a benefit but that more evidence is needed.

Surveys in the US, UK, Canada, and Australia show that the self-reported use of any stop smoking medication has increased significantly over the 2000s. The most-used medication is NRT, with use of varenicline increasing significantly.8,9 Australian data from the 2020 International Tobacco Control (ITC) project showed that among people who had tried to quit, 32% had used NRT and 13% had used prescription medication during their last attempt.10 Nationally representative data in 2022–23 showed that among Australian adults who had tried to quit in the previous year (successfully or unsuccessfully), 22% had used NRT and 6% used a smoking cessation medication.11

Choice of pharmacotherapy should take into account potential adverse effects as well as benefits.12 When pharmacotherapy combinations or dosages beyond those contained in product information and consumer medicines information are used, medical recommendation is necessary. Research has shown that ‘pre-loading’ cessation treatment (i.e., beginning to take them prior to the quit date) and extending the duration of treatment may increase abstinence and reduce relapse rates.13

Cost is also taken into account by the Australian government in deciding which pharmaceuticals to subsidise under the Pharmaceutical Benefits Scheme (PBS) and the Repatriation Pharmaceutical Benefits Scheme (RPBS). Nicotine patches were listed on the RPBS in August 1994 and December 1995 and then made available under the PBS for Aboriginal and Torres Strait Islander peoples who smoke from 2009.14,15 Availability was extended to all  Australians who smoke  in January 2011. Bupropion and varenicline are Schedule 4 in Australia so that they are available only on prescription,16 and have been available on Australia’s PBS since 2001 and 2008 respectively. From 1 January 2026 until 2030, the dispensed price for subsidised medicines is up to $7.70 for people with a concession card and up to $25.00 for other patients.17 Subsidy of medicines in Australia has clearly been associated with large and sustained increases in use.

Figure 7.16.2 shows the annual total number of prescriptions for each of the available anti-smoking medications and in total in Australia from 2001 to 2025. The sharp drop in varenicline prescriptions in 2021 reflects a pause in global distribution of Champix (see 7.16.3.3), which appears to be slowly recovering following the introduction of alternative brands.

7.16.1 Nicotine replacement therapy

Nicotine is the drug in tobacco that causes dependence.18 It is the decrease in nicotine levels that is mainly responsible for withdrawal symptoms after stopping smoking.18 NRT aims to temporarily replace some of the nicotine from cigarettes, in turn reducing motivation to smoke and nicotine withdrawal symptoms, and easing the transition from smoking to abstinence.12

NRT products are either long-acting dosing forms or faster-acting forms.19 There are advantages and disadvantages associated with each form of NRT. Nicotine patches are simple to use and the adherence rate tends to be higher than for other forms of NRT.20,21 Patches deliver nicotine more slowly than other products and when used alone, may not adequately protect against increased cravings from smoking-related stimuli. Users of the faster-acting forms have greater control over the amount and timing of the dose, and these forms are better suited to respond to sudden increases in cravings.21 However, some people only use faster-acting NRT forms in response to cravings. Underdosing is a common problem, where people don’t use enough to obtain the best clinical effect.21 Nicotine delivered via a mouth spray  is absorbed faster than nicotine delivered via gum or lozenge.22,23 There is robust evidence showing that combination NRT (long-acting plus faster-acting) is more effective than single‐form NRT24 (see Section 7.16.1.2.2, below).

E-cigarettes can provide users with inhaled doses of aerosolised nicotine mixed with a range of other chemicals. See Chapter 18 for a detailed discussion of the effectiveness of vaping for smoking cessation and an overview of the regulatory framework for e-cigarettes in Australia. 

7.16.1.1 Mechanisms and pharmacokinetics of NRT

Several mechanisms have been proposed by which NRT may assist smoking cessation. First, NRT decreases the intensity of cravings and withdrawal symptoms, enabling people to function effectively while dealing with the social and psychological aspects of their dependence. NRT does not completely eliminate all withdrawal symptoms because the available delivery systems do not replicate the rapid and high levels of nicotine that result from smoking a cigarette.25 Second, it may reduce the reinforcing effects of tobacco-delivered nicotine. Third, it may provide some of the perceived effects for which the person who smokes previously relied on cigarettes, such as sustaining desirable mood, coping with stressful situations, and maintaining concentration.21,26,27

7.16.1.2 Efficacy and effectiveness of NRT

Several reviews have concluded that NRT appears to be a safe and effective option for people who smoke who wish to quit.28,29 A Cochrane review published in 2023 concluded that users of single-forms of NRTs (i.e., patch alone or faster-acting form alone) were about 1.4 times more likely to successfully quit compared with those in control conditions. Users of combination NRT (patch plus faster-active form) had almost double the odds of quitting.2 Studies with long-term follow-up have found that the impact of a single course of NRT persists over time, with NRT users about twice as likely to not be smoking four years later than those who quit without using NRT.30

7.16.1.2.1 Dosage and mode of delivery

Some evidence suggests that dosage and speed of delivery has an impact on outcomes.31-34 Under-dosing of NRT may be one reason for lower quitting success rates among people who smoke, particularly those who smoke heavily.35 A 2023 Cochrane review found that people appeared to be more likely to quit successfully if they used higher‐dose compared with lower-dose nicotine patches or nicotine gum.5 Using either a fast-acting NRT or a nicotine patch appeared to be equally effective in terms of quit rates.5

7.16.1.2.2 Combination NRT therapy (longer-acting and faster-acting form)

In 2006, the Therapeutic Goods Administration (TGA) approved combination therapy for the concurrent use of the 15 mg 16-hour patch with 2 mg gum. There is robust evidence that combining a longer-acting form (e.g., patch) with a faster-acting form (e.g., lozenge) is more effective than single form NRT and is safe.12,36-41 A 2023 Cochrane review found that combination NRT (e.g., patch plus inhalator) appears to be equally effective as varenicline and cytisine,2 and another 2023 Cochrane review similarly concluded that there is strong evidence that using combination NRT versus single‐form NRT can increase the chances of successfully stopping smoking.5 In 2020, the US Surgeon General concluded that combination NRT increases smoking cessation compared with using single forms of NRT.1 A 2021 meta-analysis found that compared with placebo, people given combination NRT were 2.6 times more likely to successfully quit.29

Overall, researchers suggest that combination NRT likely represents one of the most promising smoking cessation strategies moving forward.42 Some have recommended that NRT labelling allow for combined use of faster-acting NRT forms with nicotine patch,36 and The Royal Australian College of General Practitioners has called for combination NRT to be subsidised under the PBS.43 Greater accessibility to and affordability of combination NRT would particularly benefit low-income groups, who have much higher smoking rates.44 The mechanisms underlying the effectiveness of combination NRT may include the higher percentage of nicotine substitution, more effective relief of cravings, and the sensory effects of different forms.12,21

7.16.1.2.3 NRT combined with behavioural support

NRT works with or without behavioural support, however behavioural support further increases the odds of success.45-47 Although a combination of NRT and behavioural support is a well-established cessation method, one study found that self-reported abstinence rates were significantly higher among participants who were sent nicotine patches compared with a control group, supporting the effectiveness of NRT in isolation.48 People who smoke making self-initiated quit attempts without formal behavioural support tend to have lower long-term success rates, but the relative effect of NRT is similar to the effects in other settings, offering significant improvement over unaided quitting.12,49-51 In Queensland, people who smoke who phone the Quitline are offered 12 weeks of free NRT, which research in the US suggests is an effective strategy, particularly for reducing smoking disparities.52

7.16.1.2.4 Duration of use

An important factor affecting success rates appears to be the duration of NRT use. Pre-quit nicotine patch use appears to increase quit rates24 and may engage additional people who smoke who are unwilling to quit.36 The US Surgeon General’s report in 2020 and a Cochrane review in 2023 found that pre-loading (e.g., initiating cessation medication in advance of a quit attempt), especially with the nicotine patch, may increase smoking cessation.1,5 The manufacturer’s recommended period of use for NRT forms substantially varies, often with provision for a gradual reduction of dosage levels to avoid withdrawal effects at the end of the period.53 However, research indicates that eight weeks of patch use is as effective as longer courses, and there is no evidence that tapered therapy is better than simply stopping after using the higher dose.12 Highly dependent people who smoke who still have cravings and withdrawal symptoms eight weeks after quitting may benefit from longer use.21,54,55 Short courses of NRT, for example four weeks, may not be effective in the long term.56 Longitudinal research in Canada found that compared with  unassisted quitting, using NRT for less than 4 weeks was associated with a lower likelihood of quitting; however, using NRT for 4 weeks or longer was associated with a higher likelihood of cessation.57 After quitting, extended use of NRT may be beneficial for lapse recovery and relapse prevention in some people who smoke.36 Findings from a 2019 Cochrane review showed that while extended NRT use did not show a benefit in preventing relapse in assisted abstainers, extended use in unassisted abstainers did suggest a benefit. However, the evidence was of low certainty.58 Continued use of NRT and tobacco during a lapse or relapse does not appear harmful and could enhance quitting outcomes.59 For example, one study found that if people continue to use a nicotine patch after a lapse they are 4–5 times more likely to quit.60 For people who do not respond to NRT, a large study from Canada suggested that offering an alternative intervention may be appropriate, with the probability of quitting highest early in NRT treatment and dropping substantially over time.61

7.16.1.2.5 Factors affecting use and adherence

The widespread availability and promotion of NRT forms has led to increased use, however there are concerns that use of NRT in the community appears to be more haphazard and less effective than among participants in research trials. A meta-analysis found poor adherence to NRT among participants of population-based studies, with only about one in four people taking it as directed.62 A population-based study in England found that people who smoke attempting to reduce their cigarette intake are often underusing NRT, which may explain why real-world studies often report less success with NRT than clinical trials.63 A study in New South Wales found that more than 40% of people who had used NRT in their most recent quit attempt had no instruction from a doctor or pharmacist on how to use the product, 61% used it for less than two weeks, and for about one-third of people, use was concurrent with smoking.20 Clinical advice and support appears to play an important role in the effectiveness of NRT, with research in England showing that users of prescription NRT had higher odds of quit success, while those who purchased it over the counter did not.64

Research suggests that many people who smoke have misperceptions about the health risks of NRT, which makes them less likely to use NRT or use it correctly.33,47,65 People who smoke tend to use less than the recommended dose or not complete the full course of treatment.66,67 Treatment adherence has been found to significantly increase abstinence rates.62,68 Using more doses of nicotine gum, nicotine lozenges and nicotine inhalator, increases quit rates.69,70 For example, one study found that for each additional lozenge used, the odds of successful quitting increase by 10%.71 Approaches to increase people who smoke’s willingness to use—and correct use of—NRT include addressing their expectations of its effectiveness, explaining clearly how it works, tailoring treatment plans, and addressing barriers to use.72 Clear and accurate information regarding the safety of NRT from health professionals can increase use and adherence.73 The literacy levels of packaging and instructions have been assessed as being above the reading levels recommended to ensure maximum comprehension.74 There is some evidence that enabling people who smoke to sample the NRT forms prior to use may result in more realistic choice of NRT and better compliance.75,76 Mailout cessation support that includes NRT appears to be effective for promoting quitting and can improve accessibility to treatment.77 Heavy alcohol use appears to undermine successful smoking cessation among those using NRT, therefore addressing alcohol use alongside smoking may be an important step.78

The use of NRT for a reason other than quitting, including temporary abstinence or reducing consumption, appears to be common. A review of NRT products available in Canada found that NRT appeared to be effective in smoking reduction for people who did not want to quit, failed from previous NRT, or intended to quit smoking gradually.79 Such usage is associated with higher education level, heavier smoking, no intention to quit, no quit attempts in the past year and the type and availability of the product used. These patterns of use may help to explain why significant benefits of NRT use are not easily detected in population studies.80

7.16.1.3 Safety of NRT

NRT is considered to be safe for most users. Discontinuation because of adverse reactions is relatively low.12 Using NRT to quit is always safer than continuing to smoke.81 When used as directed, users of NRT typically absorb a lower daily dose of nicotine than they would get from smoking a pack of cigarettes per day.21,82 While there has been concern about the potential for symptoms of nicotine overdose, studies of higher dose products and combination of NRT products have found no evidence of harm from moderate increases in nicotine intake.81,83,84 Further, research suggests that using faster-acting NRT forms alongside smoking does not appear to increase average nicotine levels, although smoking while using the nicotine patch does.83 Smoking while using NRT does not significantly increase the risk of a heart attack or other cardiovascular events.12,81 No serious adverse effects have been reported in studies of concomitant smoking and NRT use, although one study reported that nausea and vomiting were more common in the active than the placebo group.21,83 Other potential symptoms of nicotine overdose include pallor, sweating, tachycardia, agitation, and a number of less common symptoms.53

All NRT forms have a low addictive potential.85,86 Addictive potential is strongly influenced by speed and method of delivery of nicotine.81,87 When smoking a cigarette, peak blood nicotine levels are achieved within seconds, taking only 10–19 seconds for nicotine absorbed from the lungs to reach the brain, after which time it declines rapidly.81 In contrast, it can take more than 30 minutes to reach the peak blood nicotine level when using faster-acting forms of NRT,88-91 with effects of nicotine evident within 15–20 minutes.21 When using the patch, it takes four to nine hours (depending on the patch) to reach peak blood nicotine level, which then remains constant while wearing the patch.82

A paper examining the first 20 years of NRT use reported no serious adverse effects of either short or long-term use.55 The most common side effects of the patch are skin rashes where it is applied and sleep disturbance. Nicotine patches may also cause some oral health effects such as temporary xerostomia (dry mouth), vasoconstriction, ulcers, and taste disturbance,92 but these are milder and less harmful than continued smoking.93 Common side effects for the faster-acting forms include irritation of the mouth or throat, headaches, hiccups, indigestion, nausea and coughing.12,53,82,94-96 These are relatively minor for most users, and NRT is generally rated as safe compared to other medications.12,55 Although such use is uncommon, extended duration NRT is safe, and is at least as effective as short courses.36,97

While NRT has the potential for adverse effects in vulnerable developmental stages (such as during adolescence, pregnancy, and breastfeeding), it is considered to be safer alternative to smoking and can be considered under medical supervision.98-100 NRT is safe to use  in people with stable cardiovascular disease, including angina and previous heart attack.12,81 Nicotine does have some effects on the cardiovascular system, such as increased heart rate and blood pressure, however it is not the major cause of increased cardiac risk due to smoking.81

Many people who smoke believe that nicotine causes cancer, since it is equated with tobacco;81,101 however, the US Surgeon General’s 2014 report concluded that there is insufficient data to conclude that nicotine causes or contributes to cancer.102 It appears to be the other carcinogens in tobacco smoke that are responsible for smoking-related cancers.103,104 Nonetheless, many people who smoke hold misperceptions about NRT suggesting the need for interventions to improve knowledge and promote use.105

7.16.1.4 Using NRT to ‘cut down to quit’

Many people who smoke find it very difficult to stop using tobacco abruptly even using NRT. In 2007, the TGA approved the use of the ‘cut down and stop method’, where people who smoke using NRT (inhalator, mouth spray, lozenge or gum) reduce the amount they smoke over a six-week period before stopping completely. Research suggests that the addition of this method to the approved uses of NRT may increase the numbers of people who quit altogether.106 Pre-quit nicotine patch use appears to increase quit rates and may engage additional people who smoke compared with starting the patch on quit day.36,83,107,108

There has been discussion about offering NRT to people not wanting to quit but who are interested in reducing their level of smoking. The rationale is that once reduced, they may decide to quit altogether. Studies of people who smoke cutting down while using NRT have found that while blood nicotine levels generally remain stable, carbon monoxide readings decreased.109-112 Research is limited but trials indicate that NRT can achieve sustained smoking abstinence in this group. However, most trials also provided some type of behavioural support.113,114 Evidence suggests that use of NRT to ‘cut down to quit’ is effective and cost effective compared to no quit attempt.115

7.16.1.5 Scheduling and subsidy of NRT

In Australia, NRT is available in the form of a patch, gum, lozenge, mini-lozenge, and mouth spray, and previously in an inhalator (which was discontinued in early 2025). The gum and lozenge come in 4 mg and 2 mg strengths, the mini lozenges come in strengths of 4mg and 2mg, and a mouth spray delivers 1 mg per spray. There are two types of patches, each with three strengths: the 24-hour patch 21 mg, 14 mg and 7 mg strengths, and the 16-hour patch 25mg, 15 mg, and 10 mg strengths.116

Nicotine chewing gum first became available on prescription (s4) in Australia in 1984, followed by the patch in 1993.117 Throughout the 1990s and early 2000s, there were a series of amendments to the scheduling of NRT products, and nicotine patches, gum, lozenges, mouth spray, and inhalators were progressively down-scheduled to be available for sale without a prescription at pharmacies and, ultimately, from supermarkets.118 In 2005, NRT products started to appear in supermarkets. Direct advertising to the public of NRT began in 1998, which markedly increased sales.

Subsidised nicotine patches have also been available since 1994 to patients eligible for repatriation benefits and to Aboriginal and Torre Strait Islander patients since January 2009. Access to nicotine patches under the PBS was extended to all people who smoke in February 2011, and lozenges and gum were also added to the PBS in 2018. A condition for the subsidy is that the person who smokes participates in cessation counselling.

As of August 2024, there were 7 nicotine replacement patch products available on the PBS and/or RPBS. Nicotine gum and lozenge formulations were removed from the PBS on 1 July 2023.119 For further details about  individual products, see here. Since June 2023, all patients can now receive 2 x 12-week PBS-subsidised treatment courses per 12-month period.120  If a patient is unsuccessful in quitting using NRT, they can access other smoking cessation therapies on the PBS (bupropion and varenicline) during that 12-month period.

As noted above, subsidy of medicines in Australia has clearly been associated with large and sustained increases in use, and research supports the effectiveness and cost-effectiveness of universal access to cessation medications (see Section 17.4.3). For example, in 2023 Ireland expanded access to free NRT to all users of smoking cessation services, which led to a significant increase in NRT uptake which was associated with increased likelihood of quit success.121 

7.16.2 Bupropion and other anti-depressants

Bupropion is a non-nicotine medication that is approved for use as an aid to smoking cessation. Originally developed as an antidepressant, early users reported that they had less urge to smoke, and further research demonstrated that it was useful as an aid to quitting.

7.16.2.1 Mechanisms and pharmacokinetics of bupropion

The active ingredient is bupropion hydrochloride. The tablets are ‘sustained release’ which mean the bupropion is released slowly and absorbed,122 While the exact mechanism by which bupropion supports smoking cessation is unknown, its action is likely mediated through the noradrenergic and/or dopaminergic pathways.123 It relieves withdrawal symptoms and may reduce depressed mood,122,124-126 and symptoms of depression.127 Use of bupropion is associated with improved ability to resist cravings that result from ‘cues’ to smoke.128 Bupropion appears to reduce the weight gain that occurs after quitting, but the effect does not last beyond treatment.122

7.16.2.2 Efficacy of bupropion

A Cochrane review published in 2023 concluded that there is high quality evidence that bupropion increases the likelihood of long-term smoking cessation. People who use bupropion are about 60% more likely to achieve long-term cessation (vs. placebo/control), which is similar to that for single-form NRT, but lower than when using varenicline or combination NRT.6 A 2021 meta-analysis concluded that bupropion increased the odds of six-month abstinence by 2.1 times compared with placebo.29 The Cochrane review did not find any evidence that the efficacy of bupropion depended on the level or type of additional behavioural support, or whether people had a psychiatric condition.6 There is some evidence that positive beliefs and attitudes about bupropion are associated with being positive about quitting, better compliance, and potentially better outcome.129 One study found that extended use of bupropion prior to a quit attempt reduced smoking behaviour during the pre-quit period and improved short-term abstinence rates.130 Adapting treatment by adding bupropion if a person is not responding to varenicline or NRT may be a viable strategy for improving cessation.131 People with certain genetic variants appear to have lower success rate with bupropion, highlighting the potential for genetic markers to guide individualised pharmacotherapy.132

7.16.2.3 Use of bupropion in Australia

Bupropion was introduced into Australia in 2000 and listed on the PBS in February 2001, sold as 30 x 150 mg tablets (code 8465M), since February 2001 and 90 x 150 mg tablets (code 8710K), since February 2004.

It is available only on prescription, and one nine-week course per year is subsidised under the PBS on condition that users participate in a comprehensive counselling program such as with the Quitline. Since changes to the authority conditions in 2004, people who smoke wishing to use bupropion must visit a doctor for the initial 30-tablet prescription, and then make a second visit to receive the second prescription for the remaining 90 tablets.

7.16.2.4 Adverse events associated with bupropion

The most common side effects of bupropion use are sleeping difficulties, dry mouth, headache, dizziness, anxiety and nausea.127,133-136 A small number of allergic reactions to bupropion have been reported, including skin rashes or breathlessness, and, less frequently, fever, muscle and joint pain.122,133 Overdosing can cause serious side effects, including vomiting in children, rapid heartbeat in teenagers and adults and seizures. Other effects of overdose include lethargy, confusion and tremors.122 The most serious side effect is a risk of seizure, estimated to occur in 1 in 1000 patients.127 One review found that cardiovascular events in bupropion clinical trials for smoking cessation were uncommon, with no observed increase among subjects assigned to bupropion compared with placebo.137 While a large randomised trial found that use of bupropion did not appear to increase the risk of neuropsychiatric adverse events,138 a 2020 Cochrane review found high‐certainty evidence that participants randomised to bupropion were more likely to report psychiatric adverse events. This along with other side effects resulted in more trial dropouts. However, there was insufficient evidence regarding whether participants taking bupropion were more likely than those taking placebo to report serious adverse events, such death or hospitalisation.139 Bupropion is contraindicated for people who are allergic to bupropion, who are pregnant or breastfeeding, who are under 18 years of age, who have a current or previous history of seizures or eating disorders, who are currently or recently (within last 14 days) taking monoamine oxidase inhibitors, who have any tumours of the central nervous system or severe liver disease, or who are undergoing abrupt withdrawal from alcohol or benzodiazepines.140,141 There is also an increased risk of seizures occurring with bupropion in the presence of predisposing risk factors which lower the seizure threshold.123 One study also suggests that bupropion may be harmful to sperm function.142

7.16.2.5 Other antidepressants

A number of other antidepressants have been investigated for smoking cessation. A 2023 Cochrane review6 and several meta-analyses29,143 have concluded that the antidepressant nortriptyline increases quitting success. The side effects of this medication include dry mouth, constipation, nausea, and sedation, and it can be dangerous in overdose. The likelihood of quitting using nortriptyline appears to be similar to that for NRT, but lower than when using varenicline and possibly bupropion.6 Selective serotonin reuptake inhibitor antidepressants (for example, fluoxetine), monoamine oxidase inhibitors (for example, selegiline), and the antidepressant venlaxafine have not been shown to help smoking cessation, nor has S-Adenosyl-L-Methionine (SAMe), a dietary supplement that is thought to have antidepressant properties.6,139 Findings from one recent meta-analysis suggest that the herbal therapy St John’s wort may be more effective for cessation than placebo and may be more accessible than prescription medications;144 however authors of the Cochrane review argue that other anti-depressants are clearly more effective.6

None of these drugs are currently licensed for smoking cessation in Australia; however, nortriptyline is licensed for smoking cessation in New Zealand139 and is sometimes prescribed ‘off-label’ in Australia for people trying to quit.145

7.16.3 Varenicline and cytisine 

Varenicline is derived from cystine, a similar drug that has been used to assist cessation in central and eastern European countries for several decades. The active ingredient is varenicline tartrate.146 An extensive body of evidence supports the use of varenicline as a smoking cessation medication in a broad range of tobacco users with medical, behavioural, and diverse demographic characteristics.147 Recent research also supports the effectiveness of cytisine for smoking cessation.2

7.16.3.1 Mechanisms and pharmacokinetics of varenicline

Varenicline is a nicotinic receptor partial agonist (i.e., it binds to nicotinic acetylcholine receptors), which maintains moderate levels of dopamine to reduce withdrawal symptoms and the urge to smoke (i.e., cravings).148 It also acts as an antagonist by blocking nicotine binding to specific receptors, which may reduce the rewarding effects of smoking and reduce reactivity to smoking cues.146,149-152 Research also suggests that varenicline's reduction of reward anticipation in people who smoke, in addition to its previously demonstrated reduction in the negative affect associated with withdrawal, can independently and additively alter distinct brain circuits. These effects likely contribute to varenicline's efficacy as a pharmacotherapy for smoking cessation.153 Some evidence suggests that varenicline improves cognitive performance among highly dependent people who smoke using the medication to quit.154

7.16.3.2 Efficacy of varenicline

A robust body of evidence supports the efficacy of varenicline as a smoking cessation medication. A 2023 Cochrane review concluded that varenicline increased the chances of successful long-term cessation by more than two times compared to placebo.7 It may also help to prevent relapse.58 Several meta-analyses have concluded that nicotine receptor agonists increased the odds of abstinence by more than two and a half times compared with placebo.29,155 A ‘real-world’ study found that the continuous abstinence rate of varenicline users was 44.4%, with no significant gender or age differences. For every day that varenicline was taken, abstinence increased by an average of 6.6 days.156 For those ‘cutting down to quit’, a randomised clinical trial found that use of varenicline significantly increased smoking cessation rates at the end of treatment (6 months), and also at 1 year.157

A number of international studies have shown that varenicline is well tolerated and can be regarded as a cost-effective cessation treatment in people willing to quit, including users of smokeless tobacco.158-171 It also appears to be equally effective regardless of how heavily a person smokes.172 Varenicline has been found to be effective and safe in those with stable mental illness or a past history of mental illness,173,174 including in people with schizophrenia,175,176 and among people with comorbidities such as cancer or respiratory disease.177 A recent meta-analysis also supported its use in people who smoke aged 26 and under.178

Varenicline has generally been shown to be superior to bupropion and NRT.124,138,166,179-188 For example, one ‘real world’ study found that varenicline users were 3.83 more likely to be abstinent than users of NRT following a quit attempt,189 and several Cochrane reviews have also concluded that varenicline is more effective than bupropion or single forms of NRT.2,7,139,152 Compared with combination NRT (short-acting form + patch), varenicline appears to be equally effective.2,7,190,191 For people treated with combination NRT who did not achieve abstinence, switching to varenicline may be a viable ‘rescue strategy’ for enhancing cessation outcomes.192

Extended use of varenicline may also be effective.193-195 Some studies suggest that people using varenicline may struggle to maintain abstinence196 and may benefit from extended use of the medication197 or an increased dosage.192 A 2019 Cochrane review similarly found that extended treatment with varenicline can help to prevent relapse.58 Evidence on the effectiveness of using varenicline prior to the quit date (‘pre-loading’) is mixed,198 though some studies suggest it is beneficial.131,199,200 Use of varenicline also appears to increase abstinence rates among people who smoke who are not ready to quit.201 A study examining the efficacy and safety of retreatment with varenicline concluded that the medication is efficacious and well tolerated in people who have previously taken it. Abstinence rates were comparable to those reported for people who had not used varenicline before.202 Lower doses are also beneficial while lessening the incidence of adverse events.152 Although some studies have shown compliance to be an issue,203 varenicline appears to be effective in increasing cessation at 12 months even when compliance with the medication is not 100%.204 A trial that allowed participants to sample varenicline and determine their own dosage (up to the maximum dose) supported the benefits of this approach.205 Certain genotypes also appear to be associated with the likelihood of successful cessation in individuals on varenicline therapy.206,207

7.16.3.3 Use of varenicline in Australia

Varenicline was introduced into Australia as Champix® on 1 January 2008, as a prescription medicine available on the PBS to people who smoke enrolled in a smoking cessation counselling program.208

In 2021, a shortage of Champix was announced due to a pause in global distribution by the manufacturer (Pfizer), while a potential issue of contamination was investigated. The shortage is projected to impact supplies into 2025.209 Data in the US shows that Varenicline use dropped after the voluntary recall of Champix (Chantix) by Pfizer in mid-2021 and has not returned to pre-recall levels,210,211 and studies in the UK212 and Japan213 similarly show a sharp drop in the use of Champix for quitting which the authors are concerned may undermine progress in reducing smoking prevalence. In Australia, there was also a sharp drop in varenicline prescriptions in 2021, which appear to be slowly increasing following the introduction of alternative brands on the Australian Register of Therapeutic Goods (ARTG) which are available on the PBS to people who smoke who are enrolled in a smoking cessation counselling program.208

Varenicline is not suitable for pregnant women, children under 18 years of age, or people allergic to varenicline tartrate.146,214 The manufacturers’ list of illnesses for which medical advice may be needed includes having a mental illness or a history of mental illness, renal impairment, and history of seizures or other conditions potentially lowering the seizure threshold.215 Caution is recommended when operating vehicles or heavy machinery.216

Data from a number of countries show that since being introduced, varenicline has become the second most used cessation medication, behind NRT, including in Australia. Between 2006 and 2008 varenicline use rates increased from 0.0 to 14.5%. The findings suggest that varenicline did not simply gain market share at the expense of other medications, but led to an increase in people who smoke using evidence-based treatment.8 In the US, the introduction of varenicline coincided with a net increase in attempts to quit smoking and, among these, a net increase in use of stop-smoking medications.217 Canadian research concluded that both standard and extended courses of varenicline are cost-effective treatment regimens compared with alternative smoking cessation interventions.218

7.16.3.4 Adverse events associated with varenicline

Varenicline is well tolerated by most people who use it.146,216,219 The main side effect of varenicline is mild to moderate nausea, affecting about 3 out of 10 people.146,152 There is some evidence that nausea can be minimised by taking with food, titration and self-regulation of varenicline (0.5-2mg/day).220 Other side effects include stomach or bowel problems (e.g. constipation, gas, dry mouth, vomiting, indigestion), headache, dizziness, sleeping problems, unusual dreams, feeling tired, increased appetite and changes in taste.134,136,146 These side effects are usually mild to moderate and decrease over time.146,152,184,219 Side effects usually occur in the first week of taking the medicine.146 There is some evidence of adverse gastrointestinal effects when varenicline is used at maintenance dose.221 In the US, the FDA have noted a number of adverse reactions in patients drinking alcohol while being treated with varenicline, including increased intoxication, loss of memory, and aggressive or uncharacteristic behaviour. It recommends reducing alcohol consumption until the patient knows to what extent the medication affects their capacity to tolerate alcohol.222

Varenicline may cause other, less common side effects.146 Serious side effects are rare and estimated to affect up to 1 in 1000 people (0.1%).184 Very serious side effects that require urgent medical attention or hospitalisation may affect up to 1 in 10,000 people (0.01%).146 Safety warnings and revised labels have been issued in response to serious side effects from overdosing.146 Although there have been concerns about a possible association between varenicline and heart attack or stroke, research in England and Australia has found no differences in the risk of any cardiovascular event between varenicline and NRT.223 The Australian study showed decreased risk of cardiovascular death among varenicline initiators.224 A meta-analysis also found no increase in the risk of all cardiovascular disease events with bupropion or varenicline.225 A review paper concluded that there is sufficient evidence to suggest that benefits of using cessation pharmacotherapies outweighs the low risk of serious adverse cardiovascular events associated with their use, particularly in light of the high cardiovascular risk from continued smoking.226

Some people report experiencing psychiatric symptoms when they start taking the varenicline, such as depression, agitation, aggression, thoughts of self-harm, self-harm, thinking about suicide, suicidal behaviour, and hallucinations.146,152 However, a 2016 Cochrane review concluded that observational cohort studies and meta-analyses have not found a causal link between varenicline and psychiatric symptoms, including depressed mood, agitation, and suicidal behaviour. However, the evidence was not conclusive in people with past or current psychiatric disorders.152 Another 2016 systematic review and meta-analysis, this time of varenicline for smoking cessation and reduction in people with severe mental illnesses, concluded that varenicline appears to be significantly more effective than placebo for helping people with severe mental illness to reduce or quit smoking, with no clear evidence of increased risks or adverse events.227 Results of a large-scale randomised controlled trial similarly found that there was not a significant increase in neuropsychiatric adverse events attributable to varenicline.138 A large cohort study in the US found no increased risk of cardiovascular or neuropsychiatric hospitalisations in varenicline users compared with those who used NRT,228 while a British study found that varenicline was associated with a decreased risk of death, serious cardiovascular events, and neuropsychiatric events compared with NRT.229

7.16.3.5 Cytisine

Like varenicline, cytisine (cytisinicline) is a nicotinic acetylcholine receptor partial agonist.230 An increasingly robust body of research has concluded that cytisine is a low-cost and effective treatment for smoking cessation.196,231-237 The US Surgeon General concluded in 2020 that cytisine may increase smoking cessation,1 and a Cochrane review published in 2023 found that users of cytisine had more than double the odds of successfully quitting compared with control.2 A 2024 meta-analysis of RCTs found cytisine was associated with a greater likelihood of smoking cessation compared to placebo/no intervention/usual care and NRT.238 A recent trial in Australia also provided initial evidence that cytisine may be safe and effective for quitting among people with mental health disorders.239 Cytisine appears to be more effective than NRT in promoting smoking abstinence,240 and equally effective as varenicline.241 Cytisine is well-tolerated among users,242 with research to date showing fewer adverse events among cytisine than varenicline users.234,241,243 Its lower cost and fewer side effects compared with varenicline may make it a more feasible medication in some contexts.244,245 Several ‘real world’ studies have also concluded that cytisine is effective for smoking cessation.246,247 Its use for smoking cessation may also have positive effects on cardiac function.248

Based on an assessment of benefits and harms, in 2025 the World Health Organization added cytisine to its Model List of Essential Medicines, which can facilitate its inclusion in countries’ lists of effective smoking cessation medications.249 In 2026, the US-based Institute for Clinical and Economic Review (ICER) published a report evaluating cytisine for cessation, which estimated that 16 additional people per 100 remain quit at 6 months when receiving cytisine and behavioural support combined compared to behavioural support alone, and this combination was more cost-effective than behavioural support alone. Cytisine was found to be equally as effective as varenicline, but with a lower risk of nausea.250 A modelling study in the US concluded that the availability of cytisine for smoking cessation could produce major public health benefits through promoting abstinence and life-years saved, even if it was only used by a small proportion of people who smoke.251

In Australia, following consideration of public submissions and a recommendation from the Advisory Committee on Medicines Scheduling early in 2024, the Therapeutic Goods Administration made a final decision that new entries for cytisine be created in the Poisons Standard with an implementation date of October 1st. The decision creates a Schedule 3 entry (i.e., a pharmacist-only medicine) for cytisine for divided oral and oromucosal preparations with a maximum recommended daily dose of 9 mg as a smoking cessation aid for adults, and a Schedule 4 entry (i.e., prescription only) for all other preparations of cytisine.3 In early 2026, the TGA approved the first cytisine product—1.5mg tablets—for smoking cessation.252

7.16.4 Vaccines 

Researchers have attempted to develop vaccines that create antibodies that bind to nicotine in the bloodstream and prevent it from entering the brain, thus reducing the rewards of smoking and promoting cessation.19,253 254,255 Despite promising preclinical trials,256 clinical trials have not supported the efficacy of the products,257-260 and none are yet approved cessation aids. Studies generally find that abstinence rates among vaccinated people who smoke tend to be the same or lower than those in control groups, though some studies have shown higher abstinence rates among people with high antibody levels.260 A recent review again reiterated that while good safety and immune responses have generally been observed in clinical trials, these positive effects do not translate into increased cessation in subsequent clinical studies of nicotine vaccines.261

7.16.5 Combination treatments

7.16.5.1 Drug combinations

Combining approved medications is one approach to potentially improving cessation outcomes. There is robust evidence that combining a longer-acting form of NRT (e.g., patch) with a faster-acting form (e.g., lozenge) is more effective than single-form NRT and is safe12—see Section 7.16.1.2.2.  

Drugs with different mechanisms and pharmacokinetics may also be combined. Most of these combinations are yet to be approved but some show promise.68 Several systematic reviews and meta-analyses have found that combination therapy of varenicline with NRT is more effective than varenicline alone.262,263 A meta-analysis published in 2021 suggested that the most effective combination of cessation medications for achieving six-month abstinence was a nicotinic receptor agonist with NRT. Compared with placebo, people who smoke given this combination were 4.4 times more likely to successfully quit. Those given bupropion with a nicotinic receptor agonist were four times more likely to quit for six months, and bupropion and NRT 3.8 times more likely, compared with placebo.29 A recent Cochrane review found limited evidence that bupropion combined with combination NRT may increase quit rates compared with NRT alone.6 Compared with bupropion alone, a meta-analysis found that bupropion and NRT combined improved short-term cessation outcomes. While abstinence was also more likely in the longer-term, the difference was not significant.264 

Combination bupropion and varenicline appears to have greater efficacy in smoking cessation than varenicline alone,188,265,266 though a recent Cochrane review concluded that while this combination may result in higher quit rates than varenicline, more evidence is needed.6 Combination bupropion and varenicline also appears to be more effective than bupropion alone,187,266 and than varenicline combined with NRT.266 An RCT found that starting treatment with varenicline and then adding bupropion at Week 4 for those who were not able to achieve cessation by then, led to very high smoking cessation rate of 74% within 8 to 12 weeks.267

7.16.5.2 Drug plus non-drug therapies

A ‘real-world’ population study in England found that people who smoke who use a combination of behavioural support and pharmacotherapy in their quit attempts have almost three times the odds of success than those who use neither pharmacotherapy nor behavioural support.268 In a systematic review published in 2015, the US Preventive Services Task Force found that combined behavioural and pharmacotherapy interventions increased cessation by 82% compared with minimal intervention or usual care.269 A 2016 Cochrane review concluded that combining pharmacotherapy and behavioural support increase smoking cessation success compared to a minimal intervention or usual care. The authors did not find evidence that offering more intensive behavioural support was associated with larger treatment effects.270 Another Cochrane review published in 2019 concluded that providing behavioural support in person or via telephone for people using pharmacotherapy to stop smoking increases quit rates. Increasing the amount of behavioural support is likely to increase the chance of success by about 10% to 20%.271 The US Surgeon General concluded in 2020 that while behavioural counselling and cessation medications are independently effective in increasing smoking cessation, they are even more effective when used in combination.1 A review of combination therapies found that varenicline combined with behavioural therapy appears to be more effective than other pharmacotherapies combined with behavioural therapy.41

7.16.6 Other drugs that might increase quitting 

Many pharmaceutical companies and research institutions are investigating the potential for developing smoking cessation products that interfere with mechanisms involved in nicotine addiction.19,25,68,255,272 Drugs that target the cannabinoid receptor system have also been investigated.273 Rimonabant is used predominantly for treating obesity, but some thought it would also be useful for smoking cessation, particularly for people concerned about weight gain.21,274 Early clinical trials suggested a benefit for long-term smoking cessation and reduction of weight gain, especially in overweight or obese individuals.275 However, increased psychiatric side effects appeared in clinical trials.19 In October 2008 the manufacturer discontinued development of the drug.255 Some studies have suggested that antidiabetic drugs such as dulaglutide may increase smoking cessation,276 though a recent trial examining the effectiveness of dulaglutide found that it did not improve long-term smoking abstinence, but may have potential to counteract weight gain after quitting.277 Additional studies and reviews of the effectiveness of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for addressing nicotine dependence and body weight have generally concluded that early evidence shows promise for reducing cravings or improving cessation, but that more robust research is needed.278-288 

There is evidence that glutamate transmission plays an important role in relapse. A number of small studies have examined a cysteine pro-drug, N-acetylcysteine (NAC) with mixed results,289 though have generally not found support for its use290-293 Certain drugs, such as Methoxsalen, inhibit the metabolism of nicotine and may potentially support smoking cessation.294-296 Initial research in mice suggests that combining the drug with NRT may have a beneficial role in treating nicotine dependence.297,298 Delta-9-tetrahydrocannabinol (Δ9-THC) also inhibits nicotine metabolism, and an initial in vitro study suggested promise as a cessation aid.299

Topiramate is an anticonvulsant medication that may be effective as a treatment for alcohol and cocaine addiction, which has been proposed as a potential cessation aid.300-303 A pilot randomised controlled trial in 2014 found that topiramate, alone or in combination with NRT, resulted in a higher quit rate than placebo and decreased weight.304 However, a meta-analysis published in 2020 investigating the effectiveness of topiramate in smoking cessation found insufficient evidence for its use.305

Although naltrexone has been used to successfully treat opioid and alcohol dependence,306,307 a 2013 Cochrane review concluded that there was no evidence of an effect of naltrexone alone or as an adjunct to NRT on long-term smoking abstinence, and a 2014 systematic review and meta-analysis arrived at similar conclusions.308,309 An Australian drug company reported findings from a clinical trial showing that people who smoke administered the respiratory drug INV102 (nadolol) were more likely to stop smoking completely, or dramatically reduce the number of cigarettes smoked. The drug may also be useful for treating epithelial damage (i.e., damage to the tissues that line the blood vessels and organs) caused by smoking.310 A 2004 Cochrane review found low-quality evidence that the blood pressure medication clonidine may increase smoking cessation.311 Side effects include postural hypotension, extreme drowsiness, fatigue and dry mouth, which limit its usefulness.220 Another blood pressure medication, mecamylamine, has also been examined for smoking cessation, with research suggesting that combining it with NRT may increase quitting success.187 There is some evidence that the use of oral contraceptives has promise for supporting smoking cessation among women312,313—see also Section 7.19.3.

Silver acetate was marketed in the 1970s and 1980s as smoking deterrents or aversion therapy, because it produced an unpleasant taste when smoking. A 2012 Cochrane review concluded that existing trials show little evidence for a specific effect of silver acetate in promoting smoking cessation, and any effect of this agent is likely to be smaller than NRT.314 Recent studies suggest that Vernonia cinereal, a plant with medicinal properties that can make the tongue feel bitter or numb during smoking and can also inhibit the degradation of dopamine (thus increasing time between cravings), may have promise for smoking reduction and cessation.144,315 Another treatment that can create an aversive response to nicotine is NFL-101, a sterile aqueous extract of tobacco leaves delivered via injection. A recent RCT suggested that NFL-101 shows potential as a cessation aid.316 Other herbal extracts are also being studied for smoking cessation,144,317 as well as the effects of Omega-3 fatty acids.318 Very limited research also suggests that there may be a potential role of psychedelics (e.g. psilocybin, LSD) in promoting quitting.319-321

There have also been major advances in the development of personalised treatments for tobacco use. New research focusing on pharmacogenetics is emerging, based on the discovery of genetic properties influencing the pharmacokinetics and pharmacodynamics of nicotine (see Section 7.7.1.4).68 Genetic-based methods may be useful in predicting response to pharmacotherapy for sub-groups of people who smoke and assist the personalisation of treatments.56,322-326 However, a recent RCT found that prescribing smoking cessation drugs based on genetic markers, that are in theory associated with better responses to bupropion or varenicline, was less effective than prescribing varenicline in terms of treatment success.267 How quickly a person metabolises nicotine (known as the nicotine metabolite ratio; NMR) can be measured through biomarkers, and this measure may also be helpful in guiding treatment. A person with a lower NMR may benefit from NRT use, while varenicline appears to be more effective for a person with a high NMR.327,328 Biomarkers of relapse risk may also be helpful in predicting and reducing the risk of relapse.329

7.16.7 Effects of dispensing arrangements and subsidies

Reducing or covering the costs of smoking cessation medications is a highly cost-effective strategy that reduces barriers to access and use, particularly for low-income groups, and in turn increases the proportions of people successfully quitting.330,331 Research in the Netherlands found that a national reimbursement policy for smoking cessation treatment that is accompanied by media attention can increase cessation.332 Canadian research also found that the adoption of a smoking cessation medication coverage drug policy was an effective intervention to improve quit rates, the advantages of which were lost once coverage was discontinued.333 A Cochrane review similarly concluded that the provision of financial assistance for people who smoke trying to quit increase the proportion of those who attempt to quit, use smoking cessation treatments, and succeed in quitting.334 The recent provision of free NRT in Ireland to all users of smoking cessation services led to a significant increase in NRT uptake which was associated with increased likelihood of quit success.121 

Since February 2011, Australians who smoke have been able to access a 12-week supply of nicotine patches under the PBS as long as they have a medical prescription.335 Data from the Australian National Drug Strategy Household Survey show that among adults who regularly smoke, past year use of NRT (gum, patches, or inhalers) increased significantly from 14.9% in 2010 to 16.7% in 2013 (controlling for age and sex), after this change was implemented.336 Similarly, Australian research has found that reported use of prescription medication to quit smoking rose sharply with the addition of varenicline to the PBS.337

In the US, Quitlines often provide free NRT to callers. Evaluations have found that such programs increased the number of callers, in some cases quite dramatically, and most found that access to free NRT improved long-term quit rates.338-349 One US study also reported that the majority of recipients of their program were from disadvantaged groups.350 One study in which GPs gave a personalised letter to patients who smoke that encouraged them to quit and offered free NRT increased the number of people who smoke making a supported quit attempt.351 Another found that providing free NRT samples engaged both motivated and unmotivated people who smoke into the quitting process and produced positive changes in smoking outcomes.352 In Australia, Queensland has offered free NRT to Quitline callers for many years, and the Victorian Quitline is also currently running a pilot program providing free combination NRT to priority populations — see Section 7.14.

7.16.8 Methodological and ethical issues in smoking cessation trials

7.16.8.1 Conflicts of interest in smoking cessation research

Clinical research is often sponsored by companies that make the products under investigation, either because the companies directly perform the studies, or fund them.353 Potential ways that industry sponsors can influence the outcome of a study include the framing of the question, the design of the study, the conduct of the study, how data are analysed, selective reporting of favourable results, and ‘spin’ in reporting conclusions.353 A meta-analysis published in 2007 concluded that NRT trials with pharmaceutical industry funding tend to show higher success rates than those independently funded.354 The authors suggest that one possible reason for this difference may be greater resources in industry-sponsored trials, leading to higher treatment compliance and therefore greater efficacy.354 A follow-up study in 2010 found that the differential efficacy of NRT between industry-sponsored and non-industry trials may be caused by differences in the quit rate among those in the placebo condition, perhaps due to characteristics of participants recruited (in particular heaviness of smoking or level of tobacco dependence), the exclusion of participants with confounding comorbidity (such as psychiatric disorder) or the number of study sites.355 A 2012 Cochrane review concluded that sponsorship of drug and device studies by the manufacturing company leads to more favourable results and conclusions than sponsorship by other sources.353 Such trials may receive more scientific attention than trials with unfavourable findings, resulting in an overestimation of effectiveness.68 

7.16.8.2 ‘Real world’ effectiveness compared with clinical trials

Although there is robust evidence from clinical trials for the effectiveness of pharmacotherapies and behavioural interventions for quitting, population-based or ‘real-world’ studies have produced mixed results, with some reporting less successful quit rates. For example, population research in England shows that NRT appears to be less effective when purchased over the counter compared with when it is bought on prescription, potentially highlighting the critical role of health professional advice and support alongside use.64 Randomised controlled trials that enrol highly motivated people who smoke who are carefully followed up and who receive higher intensity behavioural support than is usually provided may report higher cessation rates than would occur in general population use of the medications.68 Several papers have raised concerns that strict selection criteria in cessation trials mean that many people who smoke are excluded from such trials, such as people with mental health disorders,356 and therefore the findings may not be valid or generalisable.357,358 Further, more dependent people who smoke may be more likely to use some form of treatment, but with less success, and this may artificially lower success rates.106 Researchers have argued that real-world studies of cessation treatments have often failed to adequately control for the fact that those who use these medications are more dependent upon cigarettes.

However, after adjusting for major confounding variables such as tobacco dependence, findings from population studies in England support the efficacy of varenicline64,359,360 and of combined behavioural therapy and pharmacotherapy for tobacco dependence treatment, thus supporting their use in the real world.268,361 Even small impacts of cessation medications on smoking prevalence at the population-level translates to many thousands of additional quitters. Nonetheless, policies that promote high levels of reach and access to evidence-based cessation supports alongside innovative research to increase the efficacy and attractiveness of cessation medications are needed for reducing population smoking prevalence.362

7.16.8.3 Measuring abstinence

Using a consistent definition of abstinence in smoking cessation clinical trials is crucial to both comparing results across clinical trials and for including the data in meta-analyses. Researchers have noted that defining abstinence requires specification of which products a user must abstain from (i.e., combustible tobacco, smokeless tobacco, and/or alternative products such as e-cigarettes), the type of abstinence (i.e., point prevalence or continuous), and the duration of abstinence (end of treatment, ≥3 months after the end of treatment, and ≥6 months post-quit or post-treatment initiation).363 Another review notes that biochemical verification of tobacco use and abstinence (i.e., measuring biomarkers of exposure to tobacco smoke in people’s breath, saliva, urine, blood and other samples; see also Section 12.5.6) increases scientific rigour and validity compared to self-reported cessation, but should be considered in light of its costs and limitations, including the cost of the assays, the feasibility of sample collection, the ability to draw clear conclusions based on the duration of abstinence, and the variability of the assay within the study population.364 While biochemical verification of abstinence is recommended for cessation studies, sample return rates from participants are typically low, thus strategies are needed that increase the return of samples.365,366

7.16.8.4 Adherence to cessation treatments

Another important methodological consideration in cessation studies is the extent to which compliance with directions for using and taking smoking cessation medications affects outcomes.68 There is evidence that the majority of people who smoke using stop-smoking medications do not complete the recommended course of treatment.62,66,367-369 Reasons for premature discontinuation of medication include relapse back to smoking, reported side effects and the perception that the medication has worked for the user and is no longer needed,66 while good social support, lower levels of anxiety, previous use of cessation medications, and not relapsing predicted increased adherence among a sample of Australians who smoke.368 People who smoke may have unreasonable expectations of how effective cessation medications are likely to be for them.66 Studies have shown that good adherence to varenicline370 and cytisine247 improve cessation outcomes. While adherence to cessation medications increases the likelihood of sustained smoking cessation,371 many people who smoke use them at a lower dose and for less time than is optimal.372 A Cochrane review published in 2019, which assessed the effectiveness of interventions aiming to increase adherence to cessation medications, concluded that there is moderate‐certainty evidence that enhanced behavioural support focusing on adherence to medications can modestly improve adherence. However, the authors only found weak evidence that this may slightly improve the likelihood of cessation in the shorter or longer‐term.373 Methods for ensuring and improving adherence include shared decision making,374 medication reminders,375 ‘directly observed therapy’ whereby the researcher views (in person or via video) the person using the prescribed product, or via biochemical confirmation.376 Healthcare providers can also provide adherence support, though a survey in Australia found that a lack of skill, knowledge, time and resources can act as potential barriers to the provision of such support.377 Tailored cessation plans that adapt to individual responses, preferences, and tolerability to treatments may also help to improve outcomes.378 A person’s smoking history, general health, and psychiatric health may also be helpful in predicting their likelihood of experiencing side effects, which can help guide treatment decisions.379

Beliefs about a particular treatment may influence a person who smoke’s choice of a particular medication as well as their medication experience.380 A perceived lack of need for cessation aids and beliefs that cessation aids do not help with cessation are consistently associated with medication nonadherence.381 One study found that positive medication expectancies may contribute to better treatment response, therefore assessing treatment expectations and attempting to maintain or improve them may be important for the delivery, evaluation, and targeting of smoking cessation treatments.382 Similarly, participants’ perception of treatment assignment (i.e., their beliefs about whether they have been assigned to receive a medication or a placebo) can also affect treatment outcomes. Participants’ expectancies may therefore influence treatment outcome despite use of placebo-controlled designs. Researchers suggest that inclusion of no-treatment control groups or use of active placebos may be warranted.383

7.16.8.5 Ethical considerations in smoking cessation trials

A common ethical concern about smoking cessation and other randomised controlled trials is whether it is ethical to assign participants to a non-active control condition, thereby denying some participants treatment.384 In a paper addressing such concerns, the authors argue that it is ethical to randomise when it is uncertain whether a new intervention is superior to an older one after benefits, risks, and costs have been taken into account. Other ways of overcoming this problem include a phased study in which all participants received the program eventually; trials with two distinct interventions, each of which serves as the other’s control; trials that allocate high- and low-intensity interventions; and trials that randomise to wait lists.385 A 2020 review also highlighted that interventions provided to comparator/control groups in smoking cessation trials vary substantially which can lead to very different apparent success rates. This makes some cessation interventions appear much more effective than others, whereas the differences in results may be due to a more vs. less effective/intensive comparator group intervention.386 In many health systems, patients seeking clinical care are only offered tobacco treatment if, in the opinion of the clinician, they express a desire to quit smoking or are perceived as ‘ready to quit’. Researchers have proposed that, because only a minority of tobacco users will say they are ready to quit at any given time, all tobacco users should be offered evidence-based care, without being screened for readiness as a precondition for receiving treatment. That is, receiving treatment for tobacco dependence should be ‘opt-out’ rather than ‘opt-in’. They argue that most tobacco users want to quit, there is little to no evidence supporting the utility of assessing readiness to quit, and an opt-out default is more ethical.387 See Section 7.10 for a discussion of the role of health professionals in promoting cessation.

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References

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Intro
Chapter 2