Merck Manual

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Smoking Cessation


Judith J. Prochaska

, MD, Department of Medicine, Stanford University

Last full review/revision Aug 2018| Content last modified Aug 2018
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Most smokers want to quit and have tried doing so with limited success. Effective interventions include cessation counseling and drug treatment, such as varenicline, bupropion, or a nicotine replacement product.

About 70% of US smokers say they want to quit and have already tried to quit at least once. Nicotine withdrawal symptoms can be a significant barrier to quitting.

(See also Tobacco.)

Nicotine Withdrawal

Withdrawal symptoms are often powerful enough that even with knowledge of the health risks, many smokers are unable to quit. Smoking cessation can cause intense symptoms, including strong cravings for nicotine in cigarettes, anxiety, depressed mood, inability to concentrate, irritability, restlessness, insomnia, hunger, headaches, GI disturbances, and sleep disruption. These symptoms are the worst in the first 3 days (when most smokers trying to quit relapse) and most subside within 2 to 4 wk in most smokers, but some symptoms may continue for months. Weight gain is common; quitters gain an average of 4 to 5 kg, and weight gain is another reason for relapse. Temporary cough, headaches, and constipation may develop after quitting.


About 20 million smokers in the US try to quit each year (almost half of all smokers), usually by using a cold turkey (ie, sudden, complete cessation) or other non-evidence–based approach, resulting in relapse within days, weeks, or months. Many cycle through multiple periods of relapse and remission. The long-term success rate for unassisted quitting is about 5 to 7%. In contrast, 1-yr success rates of up to 20 to 30% are achieved among smokers who use evidence-based cessation counseling and recommended drugs.

Among smokers < 18 yr, most believe they will not be smoking in 5 yr, and 40 to 50% report having tried to quit in the previous year. However, longitudinal studies show that overall, 73% of daily smokers in high school remain daily smokers 5 to 6 yr later.


Evidence-based counseling and drug treatment are both effective for treating tobacco use and addiction; combining counseling and drug treatment is more effective than either intervention alone. (See also information about tobacco cessation from the US Preventive Services Task Force [Tobacco Smoking Cessation in Adults, Including Pregnant Women: Behavioral and Pharmacotherapy Interventions].)

Smoking has many characteristics of a chronic disorder. Thus, the optimal evidence-based approach for treating smokers, particularly those not ready to quit or those who have not yet considered quitting, should be guided by the same principles that guide chronic disease management, namely

  • Continually assessing and monitoring smoking status

  • Using different evidence-based interventions (or combinations) for different patients and building on their prior experiences and treatment preferences

  • Encouraging temporary abstinence and reduction in consumption for patients who fall short of total smoking cessation while emphasizing that abstinence is the ultimate goal

Although reduction in consumption can increase motivation to quit (particularly when combined with nicotine replacement therapy), smokers should be reminded that reducing the number of cigarettes smoked may not improve health because smokers often inhale more smoke (and thus more toxins) per cigarette to maintain nicotine intake when they reduce the number of cigarettes smoked per day.

Alternative approaches to smoking cessation, such as hypnosis, acupuncture, lasers, and herbs have not proved to be effective and cannot be recommended for routine use.

Evidence-based counseling

Counseling efforts begin with the 5 A’s:

  • Ask at every visit whether a patient uses tobacco and document the response.

  • Advise all smokers to quit in clear, strong, personalized, and nonjudgmental language.

  • Assess a smoker’s willingness to quit within the next 30 days, emphasize the benefits of quitting for smokers not intending to quit in the next 30 days.

  • Assist smokers willing to make a quit attempt by providing brief counseling and drug treatment.

  • Arrange a follow-up, preferably within the first week of the quit date and again later on to prevent relapse.

For smokers willing to quit, clinicians should work with the patient to establish a quit date, preferably within 2 wk, and stress that total abstinence is better than reduction. Past quitting experiences can be reviewed to identify what helped and what did not, and smoking triggers or challenges to quitting should be planned for in advance. For example, alcohol use is associated with relapse, so alcohol restriction or abstinence should be discussed. In addition, quitting is more difficult when others smoke in the home; spouses and housemates who also smoke should be encouraged to smoke outside of the home or to quit all together. Clinicians should reinforce their availability and assistance in support of the quit attempt.

In addition to the brief counseling provided by the smoker’s clinician, counseling programs can help. They usually use cognitive-behavioral techniques and are offered by various health programs. Success rates are higher than with self-help programs. All states in the US have telephone quit lines that can provide counseling support (and sometimes nicotine replacement therapy) to smokers trying to quit. People can call 1-800-QUIT-NOW (1-800-784-8669) toll-free anywhere in the US. Quit lines appear to be at least as effective as in-person counseling. The National Cancer Institute's web site provides information, a tailored quit plan, and text-based support.

Drugs for smoking cessation

Effective and safe drugs for smoking cessation include varenicline, bupropion SR, and 5 types of nicotine replacement therapy (in the form of gum, lozenge, patch, inhaler, and nasal spray—see the table Drugs for Smoking Cessation). Bupropion’s mechanism of action is to increase the brain's release of norepinephrine and dopamine. Varenicline works at the nicotinic acetylcholine receptor (the α-4β-2 subunit), where it acts as a partial agonist, having some nicotinic effects, and as a partial antagonist, blocking the effects of nicotine. The effect of varenicline is to mitigate nicotine withdrawal symptoms and decrease the pleasurable effects of smoking if the patient has a lapse. Varenicline is the most effective monotherapy available for smoking cessation.

Combinations of different nicotine replacement products are more effective than single products and are comparable in efficacy to varenicline. For example, combining the nicotine patch with a shorter-acting nicotine replacement drug (eg, lozenge, gum, nasal spray, inhaler) is more effective than monotherapy. When used in combination, the patch helps maintain continuous levels, and use of gum, lozenge, inhaler, or nasal spray enables the patient to rapidly increase nicotine levels in response to immediate cravings. Nicotine replacement therapy is dosed at about 1 mg of nicotine replacement per cigarette smoked per day. Patients using the nicotine patch should continue wearing the patch even if they have a lapse and smoke.

Smokers may worry that they may remain dependent on nicotine after using nicotine products for smoking cessation; however, such dependence rarely persists. An important point is that the addiction potential of a drug is related to its speed of delivery to the brain. Because none of the nicotine replacement products deliver nicotine to the brain anywhere close to the speed that smoking does (8 to 10 sec), the replacement products are less addictive. Drug choice is guided by the clinician’s familiarity with the drug, the smoker's preference and previous experience (positive or negative), and contraindications.

Despite their proven efficacy, smoking cessation drugs are used by < 25% of smokers attempting to quit. Reasons for smokers not using cessation drugs in a quit attempt include low rates of insurance coverage, concerns about adverse effects and the safety of simultaneous smoking and nicotine replacement, and patient discouragement because of past unsuccessful quit attempts.

Therapies under investigation for smoking cessation include the drugs cytisine, bromocriptine, and topiramate. Vaccine therapy has been studied and found to be ineffective.


Drugs for Smoking Cessation




Adverse Effects


Bupropion SR*

150 mg every morning for 3 days (beginning 1–2 wk before quitting), then 150 mg twice/day; dose can be kept at 150 mg once/day if twice-daily regimen is not tolerated

7–12 wk initially (may continue up to 6 mo)


Dry mouth

Neuropsychiatric symptoms

Prescription only

Contraindicated by history of seizure, eating disorder, or MAOI use within the past 2 wk

Nicotine gum

If smoking > 30 min after waking: 2 mg

If smoking< 30 min after waking: 4 mg

Schedule for both dosage strengths:

1 q 1–2 h for wk 1–6

1 q 2–4 h for wk 7–9

1 q 4–8 h for wk 10–12

Up to 6 mo

Mouth soreness


OTC only

Slow chewing and parking between cheek and gum recommended to maximize blood levels and minimize gastric and esophageal irritation; can be a challenge to use enough gum to adequately address withdrawal; available in different flavors

Nicotine lozenge

If smoking > 30 min after waking: 2 mg

If smoking< 30 min after waking: 4 mg

Schedule for both dosage strengths:

1 q 1–2 h for wk 1–6

1 q 2–4 h for wk 7–9

1 q 4–8 h for wk 10–12

Up to 6 mo



Mouth sores

OTC only; available in different flavors and in a mini version; need for frequent dosing can compromise adherence

Nicotine inhaler

6–16 cartridges/day for the first 6–12 wk, then tapered down over the next 6–12 wk

3–6 mo

Local irritation of mouth and throat

Prescription only

Nicotine nasal spray

8–40 doses/day

(1 dose = 1 spray in each nostril)

14 wk

Nasal and pharyngeal irritation

Prescription only

Reaches peak blood levels earlier (in 10 min) than other nicotine replacement products

Nicotine patch

21 mg/day for 6 wk, then 14 mg/day for 2 wk, then 7 mg/day for 2 wk

If smoking> 10 cigarettes/day: 21 mg as starting dose

If smoking<10 cigarettes/day: 14 mg as starting dose

10 wk

Local skin reaction


Vivid dreams

OTC and prescription

Local skin reactions possibly less likely if location of patch is rotated; can be removed at night if bothered by vivid dreams


0.5 mg po once/day for 3 days, then 0.5 mg bid for 4 days, then 1 mg bid

12–24 wk

Most commonly, nausea and sleep disturbances

Neuropsychiatric symptoms

Prescription only

*There have been neuropsychiatric symptoms reported post-marketing, but clinical trial data have not confirmed a causal relationship. An FDA black box warning has been removed.

The longer duration of treatment may increase the likelihood of long-term abstinence among patients who have stopped smoking after 12 wk of varenicline use.

MAOI = monoamine oxidase inhibitor.

Drug safety

Contraindications to bupropion include a history of seizures, an eating disorder, and monoamine oxidase inhibitor use within 2 wk.

Postmarketing reports of serious or clinically significant neuropsychiatric adverse events when taking bupropion SR or varenicline have included changes in behavior, hostility, agitation, depressed mood, suicidal thoughts, attempted suicide, and completed suicide. Clinicians should observe patients attempting to quit smoking with varenicline or bupropion SR for the occurrence of such symptoms and advise them to stop taking varenicline or bupropion SR and contact a healthcare provider immediately if they experience such adverse events. If treatment is stopped due to neuropsychiatric symptoms, patients should be monitored until the symptoms resolve. Most experts nonetheless recommend varenicline for most smokers because the risks of smoking substantially exceed the risks of taking the drug. However, it would be reasonable to avoid varenicline in smokers with active suicidal risk.

Some patients taking varenicline report increased effects of alcohol. Instruct patients to reduce the amount of alcohol they consume until they know whether varenicline affects them.

Nicotine replacement should be used cautiously in smokers with certain cardiovascular risks (those within 2 wk of an MI, with serious arrhythmias, or with serious angina); however, most data suggest that such use is safe. Nicotine gum is contraindicated in smokers with temporomandibular joint syndrome, and nicotine patches are contraindicated in smokers with severe topical sensitization.

Because of safety concerns, inadequate efficacy data, or both, cessation drugs are not recommended for the following:

  • Pregnant smokers

  • Light smokers (< 10 cigarettes/day)

  • Adolescents (< age 18), except possibly regular heavy smokers

  • Users of smokeless tobacco

E-cigarettes and smoking cessation

E-cigarettes are another form of nicotine delivery, and some devices are believed to deliver nicotine to the brain as quickly as combusted cigarettes.

Some clinicians suggest that e-cigarettes be considered for use in smoking cessation as another type of nicotine-replacement product. The National Academies of Sciences, however, concluded there is insufficient evidence on the effectiveness of e-cigarettes as cessation devices. An additional concern is that, because nicotine inhaled from some e-cigarette devices is delivered to the brain as rapidly as nicotine from smoked cigarettes, patients might remain similarly addicted to e-cigarettes though with less harmful exposures than are associated with combusted cigarettes. Dual use (continued use of combustibles while using e-cigarettes) also is common and the health benefits of e-cigarettes in the context of dual use are unproven. In contrast, FDA-approved nicotine replacement therapies have demonstrated effectiveness in helping smokers quit with several additional benefits:

  • Few and mild side-effects

  • Low likelihood of inducing dependence

  • No potential for abuse among youth or evidence that youth will transition to using combustible tobacco products

If patients have been unsuccessful with evidence-based approaches to quitting smoking in the recent past and are intent on trying e-cigarettes, clinicians ought to provide support and encourage their efforts with a focus on switching completely from combustible to electronic cigarettes. (See also information about e-cigarettes from the The National Academies of Sciences, Engineering, and Medicine [Health and Medicine Division].)

Cessation in children

The counseling approach for children is similar to that for adults; however, cessation drugs are not recommended for smokers under the age of 18. (See also the CDC guide for Youth Tobacco Cessation.)

Children should be screened for tobacco use by age 10. Parents should be advised to maintain smoke-free households and to communicate the expectation to their children that the children will remain nonsmokers. Movies and youth video games that incorporate smoking should be avoided.

For children who smoke, cognitive-behavioral therapy that involves establishing awareness of tobacco use, providing motivations to quit, preparing to quit, and providing strategies to maintain abstinence after cessation are effective in treating nicotine dependence.

Cessation of non-cigarette tobacco products

Cessation counseling for smokeless tobacco users, as for cigarette smokers, has been shown to be effective. However, drugs have not proved effective among smokeless tobacco users.

Effectiveness of cessation treatments for pipe and cigar smokers is not well documented. Also, cessation may be affected by whether cigarettes are smoked concurrently and whether smokers inhale.

Key Points

  • Most smokers want to quit and about half of smokers make a 24-hr quit attempt each year, but less than 10% remain smoke-free at one year.

  • Evidence-based methods of smoking cessation increase the 1-yr success rate from about 5% to 20% to 30%.

  • Evidence-based counseling methods include physician counseling and referral to support programs.

  • Drug treatment (eg, varenicline, combinations of nicotine replacement products) is recommended for all patients interested in quitting, unless there is a contraindication (eg, pregnancy, < age 18, light smoker, smoke-less tobacco user).

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Drugs Mentioned In This Article

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