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Nicotine is a highly addictive drug present in tobacco and is a major component of cigarette smoke. This drug stimulates the brain reward system activated during pleasurable activities in a manner similar to that of most other addictive drugs (see Drug Use and Dependence). People smoke to feed their nicotine addiction but simultaneously inhale thousands of other components, including carcinogens, noxious gases, and chemical additives that are a part of cigarette smoke. These toxic components, rather than nicotine, are responsible for the multiple health consequences of smoking.
Epidemiology
Smoking
The percentage of people in the US who smoke cigarettes has declined since 1964, when the Surgeon General first publicized the link between smoking and ill health. Nevertheless, about 20% of adults still smoke. Smoking is most prevalent among men, people with less than a high school education, people living at or below the poverty income level, people with psychiatric disorders (including alcohol and substance use), American Indians, and Alaska natives. Smoking is less common among Hispanics and least common among Asian Americans.
Most smokers start during childhood. Children as young as 10 yr experiment with cigarettes. About 31% become addicted before age 16 and over half before age 18, and age of initiation continues to decrease. The younger the age at which smoking starts, the more likely smoking is to continue. Risk factors for childhood initiation include
Complications
Smoking harms nearly every organ in the body and is the leading cause of preventable mortality in the US, accounting for an estimated 435,000 deaths/yr, or about 20% of all deaths. About half of all current smokers die prematurely of a disease directly caused by smoking, losing 10 to 14 yr of life (7 min/cigarette) on average. Most (65%) smoking-attributable deaths are caused by ischemic heart disease, lung cancer, and chronic lung disease; the rest are caused by noncardiac vascular diseases (eg, stroke, aortic aneurysm), other cancers (eg, bladder, cervical, esophageal, kidney, laryngeal, oropharyngeal, pancreatic, stomach, throat), pneumonia, and perinatal conditions (eg, preterm birth, low birth weight, SIDS). In addition, smoking is a risk factor for other conditions that convey significant morbidity and disability, such as acute myelocytic leukemia, frequent URIs, cataracts, reproductive effects (eg, infertility, spontaneous abortion, ectopic pregnancy, premature menopause), peptic ulcer disease, osteoporosis, and periodontitis.
Quitting
About 70% of US smokers say they want to quit and have already tried to quit at least once. More than 70% of smokers present in a primary care setting every year; yet only a minority receive counseling and drugs to help them quit. Most smokers < 18 yr 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 73% of daily smokers in high school remain daily smokers 5 to 6 yr later.
Passive smoking
Passive exposure to cigarette smoke (secondhand smoke, environmental tobacco smoke) has grave health implications for children and adults. Risks to neonates, infants, and children include low birth weight, SIDS, asthma and related respiratory illnesses, and otitis media. Children exposed to cigarette smoke lose more school days because of illness than nonexposed children. Smoking-related fires kill 80 children each year and injure almost 300 more; such fires are the leading cause of deaths resulting from unintentional fires in the US. Treating children for smoking-related illnesses is estimated to cost $4.6 billion/yr. In addition, each year, 43,000 children lose one or more caregivers who die from smoking-related diseases.
For adults, passive exposure is linked to the same neoplastic, respiratory, and cardiovascular diseases that threaten active smokers. Overall, secondhand smoke is estimated to be responsible for 50,000 to 60,000 deaths each year in the US (between 2% and 3% of all deaths). These findings have led states and municipalities across the US to ban smoking within workplaces in an effort to protect the health of workers and others from the substantive risks of environmental tobacco smoke. Currently, > 50% of the US population live in a state that has implemented a comprehensive indoor smoke-free ordinance.
Symptoms and Signs
Smoking cessation often causes intense withdrawal symptoms, primarily a craving for cigarettes but also anxiety, depression (mostly mild, sometimes major), inability to concentrate, irritability, restlessness, insomnia, drowsiness, impatience, hunger, tremor, sweating, dizziness, headaches, and digestive disturbances. These symptoms are worst in the first week (when most smokers trying to quit relapse) and subside within 3 to 4 wk in most patients but may continue for months. An average weight gain of 4 to 5 kg is common and is another reason for recidivism. Coughing and oral ulcers may develop temporarily after quitting. Smokers with ulcerative colitis often experience an exacerbation soon after quitting.
Treatment
Evidence-based counseling and drug treatment are both effective treatments for tobacco dependence; combining counseling and drug treatment is more effective than either intervention alone. (See also information about tobacco cessation from the US Department of Health and Human Services Public Health Service Clinical Practice Guideline Treating Tobacco Use and Dependence: 2012 Update.)
The addiction and withdrawal symptoms are often powerful enough that even with knowledge of the many health risks, many smokers are unwilling to try quitting, and those attempting to quit are often unsuccessful. Only a minority of smokers achieve long-term remission after their initial attempts to quit; many continue to smoke for many years, cycling through multiple periods of relapse and remission. Overall, counseling, drug treatment, or both can boost success rates up to 4 times that achieved by smokers who try to quit on their own (cold turkey) without these treatments.
Smoking has many characteristics of a chronic disorder. Thus, the optimal evidence-based approach to patients, particularly those unwilling to quit or those who have not yet considered quitting, should be guided by the same principles that guide chronic disease management, namely
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.
Identifying smokers
Effective interventions require first that smokers be consistently identified (eg, by expanding the vital signs to include smoking status for all patients at every visit).
Evidence-based counseling
Counseling efforts begin with the 5 A's:
For smokers willing to quit, clinicians should 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 with another smoker in the household; spouses and housemates can be encouraged to quit together. In general, smokers should be instructed to develop social support among family and friends for their quit attempt, and clinicians should reinforce their availability and assistance in support of the attempt.
In addition to the brief counseling provided by the patient's clinician, in-person counseling programs can help. They usually use cognitive-behavioral techniques and are offered by various commercial and voluntary 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.
Drugs
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 Table 1: Smoking Cessation: Drugs for Smoking Cessation ). Bupropion's mechanism may be 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. Some evidence suggests varenicline is the most effective monotherapy available for smoking cessation.
All 7 recommended drugs for smoking cessation are effective as monotherapies, but new research suggests that combination therapy is even more effective; for example, combining the nicotine patch with a shorter-acting nicotine drug (eg, lozenge, gum, nasal spray, inhaler), bupropion, or both 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. In addition, the combination of bupropion with nicotine products may be more effective than any one therapy alone, particularly the combination of bupropion with a nicotine patch and a short-acting nicotine drug.
Smokers may worry that they may remain dependent on nicotine after using nicotine products for smoking cessation; however, such dependence rarely persists. Drug choice is guided by the clinician's familiarity with the drug, patient 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 include low rates of insurance coverage, clinician concerns about the safety of simultaneous smoking and nicotine replacement, and discouragement because of past unsuccessful quit attempts.
Therapies under investigation for smoking cessation include a vaccine that causes nicotine to be intercepted before the nicotine reaches the brain and the drugs selegiline, bromocriptine, and topiramate.
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Table 1
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| Drugs for Smoking Cessation |
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Drug
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Dosage
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Duration
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Adverse Effects
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Comments
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Bupropion SR
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150 mg every morning for 3 days (beginning 1–2 wk before quitting), then 150 mg twice/day
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7–12 wk initially (may continue up to 6 mo)
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Insomnia
Dry mouth
Possibly serious neuropsychiatric symptoms* (eg, behavior changes, agitation, depressed mood, suicidal ideation and behavior)
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Prescription only
Contraindicated by history of seizure, eating disorder, or MAOI use within the past 2 wk
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Nicotine gum
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If smoking 1–24 cigarettes/day: 2 mg gum (up to 24 pieces/day)
If smoking 25+ cigarettes/day: 4 mg gum (up to 24 pieces/day)
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Up to 12 wk
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Mouth soreness
Dyspepsia
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OTC only
Slow chewing recommended to maximize blood levels and minimize gastric and esophageal irritation
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Nicotine lozenge
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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
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Up to 12 wk
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Nausea
Insomnia
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OTC only
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Nicotine inhaler
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6–16 cartridges/day for the first 6–12 wk, then tapered down over the next 6–12 wk
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3–6 mo
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Local irritation of mouth and throat
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Prescription only
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Nicotine nasal spray
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8–40 doses/day
(1 dose = 1 spray in each nostril)
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14 wk
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Nasal and pharyngeal irritation
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Prescription only
Reaches peak blood levels earlier (in 10 min) than other nicotine replacement products
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Nicotine patch
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21 mg/24 h for 6 wk, then 14 mg/24 h for 2 wk, then 7 mg/24 h for 2 wk
If smoking > 10 cigarettes/day: 21 mg as starting dose
If smoking < 10 cigarettes/day: 14 mg as starting dose
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10 wk
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Local skin reaction
Insomnia
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OTC and prescription
Local skin reactions possibly less likely if location of patch is rotated
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Varenicline
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0.5 mg po once/day for 3 days, then 0.5 mg bid for 4 days, then 1 mg bid
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12–24 wk†
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Most commonly, nausea and sleep disturbances
Possibly serious neuropsychiatric symptoms* (eg, behavior changes, agitation, depressed mood, suicidal ideation and behavior)
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Prescription only
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*Neuropsychiatric symptoms have been reported, but clinical trial data have not confirmed a causal relationship; detecting such an association may be confounded by the presence of nicotine withdrawal.
†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.
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MAOI = monoamine oxidase inhibitor.
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Drug safety
Contraindications to bupropion include a history of seizures, an eating disorder, and monoamine oxidase inhibitor use within 2 wk.
Whether bupropion and varenicline increase risk of suicide is not clear. Varenicline and bupropion may increase risk of serious neuropsychiatric effects and accidents. In 2009, the FDA released a boxed warning for both drugs regarding these possible adverse effects. However, most experts recommend varenicline for most smokers because risks of smoking substantially exceed any possible risks of taking the drug. But varenicline should be avoided in smokers with suicidal risk, unstable psychiatric disorders, and possibly major depression.
Nicotine replacement should be used cautiously in patients 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 patients with temporomandibular joint syndrome, and nicotine patches are contraindicated in patients with severe topical sensitization.
Because of safety concerns, inadequate efficacy data, or both, drugs are not recommended for the following:
Cessation in children
The counseling approach for children is similar to that for adults; however, drugs are not recommended for patients under the age of 18. (See also the CDC guide for Youth Tobacco Cessation.)
Children should be screened for smoking and risk factors 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.
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-dependent patients. Alternative approaches to smoking cessation, such as hypnosis and acupuncture, have not proved to be effective and cannot be recommended for routine use.
Prognosis
About 20 million smokers in the US try to quit each year (almost half of all smokers), usually by using a cold turkey or other non-evidence–based approach, resulting in relapse within days, weeks, or months and a long-term success rate of about 5%. In contrast, success rates of up to 20 to 30% are achieved among smokers who use evidence-based cessation counseling and recommended drugs.
Other Kinds of Tobacco
Cigarette smoking is the most harmful form of tobacco use. However, all tobacco products contain toxins and possible carcinogens and even smokeless tobacco products are not safe alternatives to smoking.
Exclusive pipe smoking is relatively rare in the US (< 1% of people ≥ 12 yr), although it has increased among middle and high school students since 1999. In 2008, about 5.3% of people > 12 yr smoked cigars; this percentage has declined since 2000. People < 18 yr comprise the largest group of new cigar smokers. Risks of pipe and cigar smoking include cardiovascular disease; COPD; cancers of the oral cavity, lung, larynx, esophagus, colon, and pancreas; and periodontal disease and tooth loss.
About 3.3% of people ≥ 18 yr and about 7.9% of high school students use smokeless tobacco (chewing tobacco and snuff). Toxicity of smokeless tobacco varies by brand. Risks include cardiovascular disease, oral disorders (eg, cancers, gum recession, gingivitis, periodontitis and its consequences), and teratogenicity.
Cessation
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.
Last full review/revision January 2010 by Michael C. Fiore, MD, MPH, MBA
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