Benefits and risks of smoking cessation

All topics are updated as new evidence becomes available and our peer review process is complete.

Literature review current through: Sep 2016. | This topic last updated: Aug 04, 2016.

INTRODUCTION — Cigarette smoking is the leading preventable cause of mortality, responsible for nearly six million deaths worldwide and over 400,000 deaths in the United States annually [1,2]. If current trends continue, tobacco will kill more than eight million people worldwide each year by the year 2030. The three major causes of smoking-related mortality are atherosclerotic cardiovascular disease, lung cancer, and chronic obstructive pulmonary disease (COPD) [2].

Smokers who stop smoking reduce their risk of developing and dying from tobacco-related illnesses [3,4]. Screening all patients for tobacco use and providing smokers with behavioral counseling and pharmacotherapy to stop smoking are among the most valuable preventive services that can be offered in health care [5].

This topic will discuss the benefits and risks of smoking cessation. Management of smoking cessation, including the use of behavioral and pharmacologic therapies, is discussed in detail separately. (See "Overview of smoking cessation management in adults" and "Behavioral approaches to smoking cessation" and "Pharmacotherapy for smoking cessation in adults".)

BENEFITS OF SMOKING CESSATION — Smoking cessation is associated with substantial health benefits for all smokers [6]. The extent of benefit partly depends on the intensity and duration of prior tobacco smoke exposure. Smokers who stop smoking can be expected to live longer and are less likely to develop tobacco-related diseases, including coronary heart disease, cancer, and pulmonary disease. Smokers also benefit from quitting smoking even after the development of smoking-related diseases, such as coronary heart disease or chronic obstructive pulmonary disease (COPD).

All-cause mortality — Up to one-half of all smokers can be expected to die from a tobacco-related illness [1]. In one population-based cohort of nearly 50,000 people aged 40 to 70 years in Norway, the years of life lost were 1.4 years in women and 2.7 years in men among those who smoked ≥20 cigarettes daily, compared with those who never smoked [7].

Smoking cessation is associated with a mortality benefit for both men and women of all ages [4,7-10]. Stopping smoking at younger ages, especially before age 40, is associated with a larger decline in premature mortality than stopping at a later age [3,7,11]. However, quitting smoking after age 60 years is still associated with a lower risk of death compared with older adults who continue to smoke [7,10,12]. Even in smokers over age 80, quitting smoking appears to reduce mortality [12].

Cardiovascular disease — Cigarette smoking is estimated to be responsible for >10 percent of all cardiovascular deaths worldwide [13] and 33 percent of all cardiovascular deaths in the United States [14].

Nicotine from tobacco use can lead to several harmful effects on the cardiovascular system, including coronary vasoconstriction, increased hypercoagulability, dyslipidemia, and endothelial dysfunction. Smoking cessation is associated with a substantial reduction in the risk of cardiovascular events (including myocardial infarction, sudden cardiac death, and stroke) for both individuals with and without a prior history of cardiovascular disease. (See "Cardiovascular risk of smoking and benefits of smoking cessation".)

Smoking cessation also reduces the progression of symptomatic peripheral artery disease and is associated with a reduced risk of recurrent stroke. (See "Overview of secondary prevention of ischemic stroke".)

Malignancy — Smoking is a major risk factor for many types of cancer (table 1), and tobacco cessation is associated with a reduction in cancer risk. Among smokers with a smoking-related cancer, smoking cessation may also decrease the risk of developing a second smoking-related malignancy [15]. The relationships between smoking and different types of cancer are discussed in detail separately:

●(See "Cigarette smoking and other possible risk factors for lung cancer".)

●(See "Multiple primary lung cancers".)

●(See "Factors that modify breast cancer risk in women", section on 'Smoking'.)

●(See "Epidemiology and risk factors for head and neck cancer", section on 'Smoking'.)

●(See "Risk factors for gastric cancer", section on 'Smoking'.)

●(See "Epidemiology and nonfamilial risk factors for exocrine pancreatic cancer", section on 'Cigarette smoking'.)

●(See "Epidemiology, pathology, and pathogenesis of renal cell carcinoma", section on 'Smoking'.)

●(See "Epidemiology and risk factors of urothelial (transitional cell) carcinoma of the bladder", section on 'Smoking cessation'.)

●(See "Epithelial carcinoma of the ovary, fallopian tube, and peritoneum: Epidemiology and risk factors", section on 'Cigarette smoking'.)

●(See "Cervical intraepithelial neoplasia: Terminology, incidence, pathogenesis, and prevention", section on 'Cigarette smoking'.)

●(See "Carcinoma of the penis: Epidemiology, risk factors, and pathology", section on 'Other factors'.)

●(See "Classification and epidemiology of anal cancer", section on 'Cigarette smoking'.)

●(See "Cancer prevention", section on 'Tobacco use'.)

 

Pulmonary disease — Epidemiologic studies indicate that cigarette smoking is overwhelmingly the most important risk factor for COPD.

Smoking cessation reduces the accelerated decline of lung function and risk of incident COPD associated with smoking [16]. In addition, the majority of smokers with cough and sputum production with early COPD have an improvement in symptoms in the first 12 months after cessation [17]. The risk of COPD exacerbations also declines over time after smoking cessation [18]. (See "Chronic obstructive pulmonary disease: Risk factors and risk reduction", section on 'Smoking cessation'.)

Smoking is associated with other chronic lung conditions, including asthma and respiratory bronchiolitis. Smoking cessation leads to an improvement in respiratory symptoms in these patients. (See "Risk factors for asthma", section on 'Smoking and exposure to environmental tobacco smoke' and "Respiratory bronchiolitis-associated interstitial lung disease", section on 'Smoking cessation'.)

Infections — Cigarette smoking is associated with an increased risk of several types of infection, including tuberculosis, pneumococcal pneumonia, Legionnaires disease, meningococcal disease, influenza, and the common cold [19,20]. Although smoking cessation may reduce the risk of several types of infection, there are little data available to support this. (See "Epidemiology of tuberculosis", section on 'Risk factors' and "Pneumococcal pneumonia in adults", section on 'Smoking' and "Epidemiology and pathogenesis of Legionella infection", section on 'Host risk factors' and "Epidemiology of Neisseria meningitidis infection", section on 'Other host factors'.)

Diabetes — The number of cigarettes smoked daily is associated with an increased risk for developing type 2 diabetes mellitus over the long-term. This may be partly due to nicotine’s effect on impaired insulin sensitivity. Although there does appear to be an increased risk of developing type 2 diabetes shortly after quitting tobacco use (perhaps partly due to weight gain), smoking cessation reduces the risk of diabetes after several years of abstinence [21]. (See "Risk factors for type 2 diabetes mellitus", section on 'Smoking'.)

Osteoporosis and hip fracture — Smoking accelerates bone loss and is a risk factor for hip fracture in women [22]. Smoking cessation can reverse loss of bone mineral density and decrease the excess risk of hip fracture after approximately 10 years after quitting tobacco use (relative risk [RR] 0.7, 95% CI 0.5-0.9) [23,24]. (See "Osteoporotic fracture risk assessment", section on 'Cigarette smoking' and "Overview of the management of osteoporosis in postmenopausal women", section on 'Cessation of smoking'.)

Reproductive disorders — Smoking is associated with an increased risk of several reproductive disorders, including complications during pregnancy, premature menopause, erectile dysfunction, and subfertility in both men and women. In particular, maternal smoking is associated with spontaneous abortion, ectopic pregnancy, lower birth weight, and a number of diseases in the fetus, some of which may develop late in life. Maternal smoking cessation results in improved fetal and maternal outcomes. (See "Cigarette smoking: Impact on pregnancy and the neonate".)

Peptic ulcer disease — Gastric and duodenal ulcer disease is more likely to occur and take more time to heal in smokers compared with nonsmokers [25]. Smoking is associated with Helicobacter pylori infection, a well-established etiologic agent for peptic ulcer disease [26]. Persistent smoking increases treatment failure rates for H. pylori eradication [26]. Smoking cessation decreases the risk of developing peptic ulcer disease and accelerates the rate of healing in established disease [27,28]. (See "Epidemiology and etiology of peptic ulcer disease".)

Periodontal disease — The number of cigarettes smoked daily is associated with an increased risk of developing periodontal disease, including gingivitis and periodontitis [29]. In a large population-based survey, the risk of periodontitis in former smokers declined with the number of years after smoking cessation [30]. (See "Gingivitis and periodontitis in adults: Classification and dental treatment".)

Postoperative complications — Smoking cessation prior to surgery may prevent postoperative complications, including delayed wound healing and pulmonary complications. In addition, longer periods of smoking cessation prior to surgery are associated with lower rates of postoperative complications. (See "Preoperative medical evaluation of the adult healthy patient", section on 'Smoking'.)

Other — Smoking has also been associated other adverse health effects. A study using pooled data from five large cohorts including over 420,000 men and 530,000 women aged ≥55 years found that compared with never-smokers, current smokers had an increased risk of mortality from renal failure (RR 2.4, 95% CI 1.9-3.0), intestinal ischemia (RR 6.0, 95% CI 4.5-8.1), hypertensive heart disease (RR 2.4, 95% CI 1.2-1.5), any infection (RR 2.3, 95% CI 1.6-2.4), breast cancer (RR 1.3, 95% CI 1.2-1.5), and prostate cancer (RR 1.4, 95% CI 1.2-1.7) [31]. The study also found an increased risk of mortality from respiratory illnesses other than pneumonia, influenza, COPD, and pulmonary fibrosis (RR 2.0, 95% CI 1.6-2.4). Smoking cessation decreased the risks, with the risks continuing to decrease as the duration of smoking cessation increased.

QUESTIONABLE UTILITY OF SMOKING REDUCTION — Reducing the number of cigarettes smoked daily has been advocated as a possible alternative to complete cessation in patients who are unable to quit smoking. However, few data are available that support a strategy for a reduction in smoking, compared with complete cessation. Consistent benefits in cardiovascular disease risk have not been seen with reduction in smoking short of quitting [14]. This is because even low levels of tobacco smoke exposure increase cardiovascular risk. At least two prospective cohort studies found that smokers who reduced smoking by at least 50 percent had no change in all-cause mortality, whereas those who quit smoking completely had decreased risk of all-cause mortality [32,33].

However, a cohort study that followed 4633 Israeli men from 1965 through 2005 found reduced risk for mortality associated with smoking reduction (hazard ratio [HR] 0.85, 95% CI 0.77-0.95); the benefit with smoking reduction was mainly seen in heavy smokers and was mainly due to a reduction in cardiovascular mortality [34]. A separate cohort study also found that a reduction in smoking may decrease the risk of lung cancer (table 2) [35]. (See "Cigarette smoking and other possible risk factors for lung cancer", section on 'Smoking reduction'.)

One reason that a reduction in smoking may not consistently improve health outcomes is that smokers may compensate for smoking reduction with increased puffs, volume, or duration in order to maintain nicotine intake and forestall nicotine withdrawal symptoms. Smoking reduction remains controversial as a strategy for reducing the health risks of smokers [36]. Complete smoking cessation is preferable.

RISKS OF SMOKING CESSATION — Although the risks of smoking cessation are far outweighed by the benefits, these risks are important to address in order to maximize the likelihood that a patient will successfully quit tobacco use. (See "Behavioral approaches to smoking cessation".)

Nicotine withdrawal syndrome — Nicotine is a potent psychoactive drug that causes physical dependence and tolerance [6]. In the absence of nicotine, a smoker develops cravings for cigarettes and symptoms of the nicotine withdrawal syndrome. Symptoms generally peak in the first three days and subside over the next three to four weeks, but smokers’ cravings for cigarettes may persist for months to years. Nicotine withdrawal symptoms include:

●Increased appetite or weight gain

●Dysphoric, depressed mood, or anhedonia [37]

●Insomnia

●Irritability, frustration, or anger

●Anxiety

●Difficulty concentrating

●Restlessness

 

These factors should be addressed so that smokers will know what to expect and how to respond if these symptoms occur. Smoking cessation medications, including nicotine replacement therapy, bupropion, and varenicline, relieve the symptoms of nicotine withdrawal (see "Pharmacotherapy for smoking cessation in adults"). Nonpharmacologic approaches can also help to manage nicotine withdrawal symptoms. (See "Behavioral approaches to smoking cessation".)

Weight gain — Weight gain commonly occurs after cessation of smoking. Weight gain is a principal fear of those who are considering smoking cessation, especially women. The mechanisms behind weight gain appear to be decreased metabolic rate, increased activity of lipoprotein lipase, changes in food preferences, and increased caloric intake [38]. Weight gain of 1 to 2 kg in the first two weeks is usually followed by an additional 2 to 3 kg weight gain over the next four to five months [39,40]. The average total weight gain is 4 to 5 kg, but may be much greater. Ten percent or more of quitters may gain over 13 kg after smoking cessation. In general, the amount of weight gain is greater in women than men, nonwhites compared with whites, and heavier smokers compared with lighter smokers [41].

While there are well-recognized health hazards of obesity (see "Obesity in adults: Health hazards"), these are outweighed by the health benefits of quitting smoking, which are much larger than the additional risk conferred by the weight gain. Behavioral counseling that addresses weight gain, including dietary or physical activity interventions, has some success in limiting weight gain (see "Behavioral approaches to smoking cessation"). Weight gain can also be temporarily blunted in smokers who quit with bupropion, an antidepressant medication effective for smoking cessation. (See "Pharmacotherapy for smoking cessation in adults", section on 'Bupropion'.)

Depression — Nicotine withdrawal syndrome includes symptoms of depression and anxiety, particularly in those with a history of psychiatric illness. In patients with documented depression, smoking cessation has been reported to trigger depressive episodes that require behavioral counseling, antidepressant medication, or both [42,43]. However, despite this increase in depressive symptoms, subsequent studies have found that the benefits of smoking cessation outweigh the risks in patients with psychiatric illness [44,45]. (See "Unipolar depression in adults: Assessment and diagnosis".)

It is unclear if smoking cessation causes depression in smokers who do not have psychiatric illness at baseline. In one large cohort of smokers without depression or anxiety, there was no increase in symptoms of depression or anxiety after quitting tobacco use [46].

Cough and mouth ulcers — A temporary increase in cough and aphthous ulcers can occur in the first few weeks after stopping smoking [47-49]. The pathophysiology is not well-understood. Coughing and aphthous ulcers generally resolve several weeks after the quit date. Individuals with bronchitis who quit may also report an increase in cough, but the most common experience is a decrease is symptoms as noted above [17].

COST-EFFECTIVENESS — Smoking cessation interventions, including both counseling and medications, are highly cost-effective when compared with other commonly accepted preventive health practices (table 3) [50,51]. One study examined several smoking cessation strategies with and without nicotine replacement and calculated an approximate cost of USD $2587 per net year of life gained, based upon published estimates of success and mortality differences for smokers and nonsmokers [51]. A second study examined smokers at a single institution who completed an initial 60-minute nicotine dependence consultation and six two-hour evening sessions devoted to smoking cessation [50]. The cohort was followed for one year, and based upon quit rates at that time and published mortality rates by age, sex, smoking status, and number of years since quitting, a mathematical model estimated a cost of USD $6828 per net year of life gained. Both of these estimates are considerably more favorable than those of other common interventions. As one example, treatment of mild hypertension costs approximately USD $24,000 per net year of life gained [52].

Subsequent studies have found several behavioral and pharmacologic therapies for smoking cessation to be cost-effective [53]. Telephone quitlines appear to be among the most cost-effective strategies [54].

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●Basics topics (see "Patient education: Quitting smoking (The Basics)")

 

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SUMMARY AND RECOMMENDATIONS

●Cigarette smoking is the leading preventable cause of mortality and is estimated to cause nearly six million deaths worldwide each year. Up to one-half of all regular smokers can be expected to die from a tobacco-related illness. The most important causes of smoking-related mortality are atherosclerotic cardiovascular disease, lung cancer, and chronic obstructive pulmonary disease (COPD). (See 'Introduction' above.)

 

●Smoking cessation is associated with substantial health benefits, including a reduced risk of coronary heart disease, cancer, pulmonary disease, infections, and hip fracture. Smokers also benefit from quitting smoking even after the development of smoking-related diseases, such as coronary heart disease or COPD. (See 'Benefits of smoking cessation' above.)

 

●Smoking cessation is associated with a mortality benefit for both men and women of all ages. Stopping smoking before age 40 is associated with a larger decline in premature mortality than stopping at a later age. (See 'All-cause mortality'above.)

 

●Smoking cessation often leads to nicotine withdrawal symptoms, including increased appetite, weight gain, depressive symptoms, anxiety, insomnia, irritability, difficulty concentrating, and restlessness. Nicotine withdrawal symptoms are temporary and can be treated by pharmacologic or behavioral treatments. (See 'Risks of smoking cessation' above.)

 

●Since tobacco use is both a learned behavior and a physical addiction to nicotine for the majority of smokers, the most effective way to promote smoking cessation is to combine both behavioral and pharmacologic therapies, which have a higher quit rate than either therapy alone. (See "Overview of smoking cessation management in adults".)

 

ACKNOWLEDGMENT — The editorial staff at UpToDate would like to acknowledge Dr. Stephen Rennard, MD, and Mr. David Daughton, MS, who contributed to an earlier version of this topic review.

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