Merck Manual

Please confirm that you are a health care professional

honeypot link

Smoking Cessation


Judith J. Prochaska

, PhD, MPH, Stanford Prevention Research Center, Stanford University

Reviewed/Revised Dec 2020 | Modified Sep 2022
View Patient Education
Topic Resources

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.

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, gastrointestinal 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 weeks in most smokers, but some symptoms, such as craving, 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.

Prognosis for Smoking Cessation

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-year success rates of up to 20 to 30% are achieved among smokers who use evidence-based cessation counseling and recommended drugs.

Among smokers < 18 years, most believe they will not be smoking in 5 years, 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 years 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.

Can a Smartphone App Help You Quit Smoking?

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 weeks, 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 Drugs for Smoking Cessation 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 alpha-4 beta-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 of nicotine, 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 seconds), 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.


Drug safety

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

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 Etiology Suicide is death caused by an intentional act of self-harm that is designed to be lethal. Suicidal behavior encompasses a spectrum of behavior from suicide attempt and preparatory behaviors... read more .

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.

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, US Food and Drug Administration-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]: Public health consequences of e-cigarettes.)

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 Centers for Disease Control and Prevention — Youth Tobacco Prevention.)

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-hour quit attempt each year, but less than 10% remain smoke-free at 1 year.

  • Evidence-based methods of smoking cessation increase the 1-year 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).

More Information

The following English-language resources may be useful. Please note that The Manual is not responsible for the content of these resources.

Drugs Mentioned In This Article

Drug Name Select Trade
Chantix, Tyrvaya
Aplenzin, Budeprion SR , Budeprion XL , Buproban, Forfivo XL, Wellbutrin, Wellbutrin SR, Wellbutrin XL, Zyban
Commit, Habitrol, Nicoderm CQ, NICOrelief , Nicorette, Nicotrol, Nicotrol NS
Cycloset, Parlodel
EPRONTIA, Qudexy XR, Topamax, Topamax Sprinkle, Topiragen , Trokendi XR
View Patient Education
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!