Smoking is the inhalation of the smoke of burning tobacco encased in cigarettes, pipes, and cigars. Casual smoking is the act of smoking only occasionally, usually in a social situation or to relieve stress. A smoking habit is a physical addiction to tobacco products. Many health experts now regard habitual smoking as a psychological addiction with serious health consequences.


Nicotine is the active ingredient in tobacco. In smoking, it is inhaled into the lungs, where most of it stays. The rest passes into the bloodstream, reaching the brain in about 10 seconds and dispersing throughout the body in about 20 seconds. The United States Food and Drug Administration (FDA) has asserted that cigarettes and smokeless tobacco should be considered nicotine delivery devices.

Depending on the circumstances and the amount consumed, nicotine can act as either a stimulant or a tranquilizer. This can explain why some people report that smoking gives them energy and stimulates their mental activity, while others note that smoking relieves anxiety and relaxes them. The initial “kick” that comes from smoking results in part from the drug's stimulation of the adrenal glands and resulting release of epinephrine into the bloodstream. Epinephrine causes several physiological changes: it temporarily narrows the arteries, raises the blood pressure, raises the levels of fat in the blood, and increases the heart rate and flow of blood from the heart. Some researchers think epinephrine release contributes to smokers' increased risk of high blood pressure.

When a person smokes, he or she is ingesting a lot more than nicotine. Smoke from a cigarette, pipe, or cigar is made up of many additional toxic chemicals, including tar and carbon monoxide. Tar is a sticky substance that forms into deposits in the lungs, causing lung cancer and respiratory distress. Carbon monoxide limits the amount of oxygen that the red blood cells can convey throughout your body. Also, it may damage the inner walls of the arteries, which allows fat to build up in them.

Some brands of cigarettes are advertised as “low tar,” but no cigarette is safe. If smokers switch to a low-tar cigarette, they are likely to inhale longerand more deeply to get the chemicals their body craves. A smoker has to quit the habit entirely in order to improve his health and decrease the chance of disease.

Although some people believe chewing tobacco is safer, it also carries health risks. People who chew tobacco have an increased risk of heart disease and mouth and throat cancer. Pipe and cigar smokers have increased health risks as well, even though these smokers generally do not inhale as deeply as cigarette smokers do. These groups have not been studied as extensively as cigarette smokers. There is some evidence that they may be at a slightly lower risk of cardiovascular problems but a higher risk of cancer and various types of circulatory conditions.

Risk factors

Socioeconomic factors play a role in who is likely to begin smoking. Two major indicators are low income and low level of education. In addition, people who live with smokers or who come from families where smoking is considered acceptable are more likely to begin smoking.

Researchers think that genetic factors may contribute substantially to developing a smoking habit. Several twin studies have led to estimates of 46–84% heritability for smoking. It is thought that some genetic variations affect the speed of nicotine metabolism in the body and the activity level of nicotinic receptors in the brain.


According to the Centers for Disease Control and Prevention (CDC), in 2010 (data reported in 2012), 19.3% of Americans over age 18 (more than 45.3 million people) were smokers. Men comprised 21.5% of smokers while 17.3% of women smoked. Fromages 18–64, the rate of smoking is about 21%, but the rate drops drastically after age 65 to 9.5%.

In the United States, more Native Americans smoke than any other racial or ethnic group (31.4%), while Asian Americans smoke the least (9.2%). The more education a person has, the less likely he or she is to smoke. About 45.2% of adults who have obtained a GED diploma smoke compared to 6.2% of people with a postgraduate college degree.

The highest rates of smoking are found in the Southeast and Midwest. Utah has the lowest rate of smoking (9.1%) and West Virginia the highest (26.8%). Substantially more people whose incomes fall below the poverty level smoke than those whose incomes are at or above the poverty level.

Causes and symptoms

No one starts smoking intending to become addicted to nicotine. It is not known how much nicotine may be consumed before the body becomes addicted. However, once smoking becomes habitual, the smoker faces a lifetime of health risks.

Smoking risks

Smoking is recognized as the leading preventable cause of death in the United States. According to the CDC, each year smoking causes approximately 443,000 deaths and secondhand smoke contributes to almost 50,000 more. Smoking causes more deaths than human immunodeficiency virus (HIV), illegal drug use, alcohol use, motor vehicle injuries, suicides, and murders combined. Smokers live on average 12 years less than nonsmokers. In addition people who smoke have an increased chance of developing cancer of the lung, esophagus, lips and mouth, larynx, pancreas, kidney, urinary bladder and cervix (women); increased likelihood of developing chronic respiratory diseases such as emphysema, asthma, and chronic bronchitis; and cardiovascular disease, such as heart attack, high blood pressure, stroke, and atherosclerosis (narrowing and hardening of the arteries). The risk of stroke is especially high in women who take oral contraceptives (birth control pills).

Smoking can damage fertility, making it harder to conceive, and it can interfere with the growth of the fetus during pregnancy. It accounts for an estimated 14% of premature births and 10% of infant deaths. There is some evidence that smoking may cause impotence in some men.

Because smoking affects so many of the body's systems, smokers often have vitamin deficiencies and suffer oxidative damage caused by free radicals. Free radicals are molecules that steal electrons from other molecules, turning the other molecules into free radicals and destabilizing the molecules in the body's cells.

Smokers' symptoms

Smokers are likely to exhibit a variety of symptoms that reveal the damage caused by smoking. A nagging morning cough may be one sign of a tobacco habit. Other symptoms include shortness of breath, wheezing, and frequent occurrences of respiratory illness, such as bronchitis. Smoking also increases fatigue and decreases the smoker's sense of smell and taste. Smokers are more likely to develop poor circulation, with cold hands and feet and premature wrinkles.

Sometimes the illnesses that result from smoking come on silently with little warning. For instance, coronary artery disease may exhibit few or no symptoms. At other times, there will be warning signs, such as a hacking cough that brings up phlegm or blood—a sign of lung cancer.

Withdrawal symptoms

A smoker who tries to quit may expect one or more of these withdrawal symptoms: nausea, constipation or diarrhea, drowsiness, loss of concentration, insomnia, headache, nausea, and irritability.


Smokers know they smoke. They do not need a doctor to tell them they are addicted. However, because it is hard to quit smoking, it may be wise for a smoker to turn to a healthcare practitioner for help. For the greatest success in quitting and to help with the withdrawal symptoms, the smoker should talk over a treatment plan with his doctor or alternative practitioner. Often, the smoker will have a general physical examination to gauge general health status and uncover any smoking-related health problems along with developing a smoking cessation treatment plan.


Research shows that most smokers who want to quit benefit from the support of other people. It helps to quit with a friend or to join a group such as those organized by the American Cancer Society. These groups provide support and teach behavior modification methods that can help the smoker quit. The smoker's physician can often refer him to such groups or to a psychotherapist who has experience treating people who are trying to quit smoking.

For those who do quit, the benefits to health are worth the effort. Once a smoker quits, the health effects are immediate and dramatic. After the first day, oxygen and carbon monoxide levels in the blood return to normal. At two days, nerve endings begin to grow back and the senses of taste and smell revive. Within two weeks to three months, circulation and breathing improve. After one year of not smoking, the risk of heart disease is reduced by 50%. After 15 years of abstinence, the risks of health problems from smoking virtually vanish. A smoker who quits for good often feels better, with less fatigue and fewer respiratory illnesses.

Nicotine replacement

It is very difficult to simply stop smoking. The greatest success rate in quitting smoking is achieved by people who seek help with the withdrawal symptoms. Common smoking cessation aides provide nicotine replacement therapy in the form of gum, patches, nasal sprays, and oral inhalers. These are available by prescription or over the counter. A health care provider can give advice on how to use them.

Nicotine replacement therapies release a small amount of nicotine into the bloodstream, satisfying the smoker's physical craving for nicotine. Over time, the amount of nicotine is decreased (e.g., the amount of nicotine gum the smoker chews or the strength of the nicotine patch is decreased). This helps wean the smoker from nicotine slowly, eventually beating his addiction to the drug. However, if the person begins smoking again while using a nicotine replacement therapy, nicotine overdose may cause serious health problems.

Drugs therapy

The prescription drug Zyban (bupropion hydrochloride) is an antidepressant that has shown success in helping smokers quit. This drug contains no nicotine and was originally developed as an antidepressant. It is unclear exactly how bupropion works to suppress the desire for nicotine. A five-year study of bupropion reported that the drug has a very good record for safety and effectiveness in treating tobacco dependence. Its most common side effect is insomnia, which can also result from nicotine withdrawal.

Varenicline (Chantix) was approved by the FDA in 2006 for treatment of smoking addiction. The drug reduces the desire for nicotine by stimulating the same receptors in the brain as nicotine, but more weakly, thus reducing the craving for nicotine. The drug is approved for use in people over age 18 for 12 weeks. In 2011, a study found that the drug increased the risk of serious cardiovascular events. As of mid-2012, the drug is still available and research on side effects continues.

Alternative treatment

A wide range of alternative and complementary treatments help some smokers stop smoking. These include hypnotherapy, herbs, acupuncture, and meditation. Many people use these treatments in addition to, rather than as a substitute for nicotine replacement or drug therapy.


Hypnotherapy helps the smoker achieve a trancelike state, during which the deepest levels of the mind are accessed. A session with a hypnotherapist may begin with a discussion of whether the smoker really wants to and truly is motivated to stop smoking. The therapist will explain how hypnosis can reduce the stress-related symptoms that sometimes come with quitting smoking.

Often the therapist will discuss the dangers of smoking with the patient and begin to “reframe' the patient's thinking about smoking. Many smokers are convinced they cannot quit and the therapist can help persuade them that they can change this behavior. These suggestions are then repeated while the smoker is under hypnosis. The therapist may also suggest while the smoker is under hypnosis that his feelings of worry, anxiety, and irritability will decrease.

In a review of 17 studies of the effectiveness of hypnotherapy, the percentage of people treated by hypnosis who still were not smoking after six months ranged from 4–8%. In programs that included several hours of treatment, intense interpersonal interaction, individualized suggestions, and follow-up treatment, success rates were above 50%.


One study demonstrated that inhaling the vapor from black pepper extract may reduce symptoms associated with smoking withdrawal. Other essential oils can be used for relieving the anxiety a smoker often experiences while quitting.


A variety of herbs may help smokers reduce their cravings for nicotine, calm their irritability, and even reverse the oxidative cellular damage done by smoking. Lobelia, sometimes called Indian tobacco, has historically been used as a substitute for tobacco. It contains a substance called lobeline, which decreases the craving for nicotine by bolstering the nervous system and calming the smoker. In high doses, lobelia can cause vomiting but the average dose—about 10 drops per day—should pose no problems.

Any substance that reduces the damage caused by oxidation, such as the harm caused by free radicals.
Chronic bronchitis—
A smoking-related respiratory illness in which the membranes that line the bronchi, or the lung's air passages, narrow over time. Symptoms include breathlessness, wheezing, and a morning cough that brings up phlegm.
An incurable, smoking-related disease, in which the air sacs at the end of the lung's bronchi become weak and inefficient. People with emphysema often first notice shortness of breath, repeated wheezing, and coughing that brings up phlegm.
A nervous system hormone stimulated by the nicotine in tobacco. It increases heart rate and may raise smokers' blood pressure.
A food chemical that helps to limit oxidative damage to the body's cells and protects against heart disease and cancer.
Free radical—
An unstable molecule that causes oxidative damage by stealing electrons from surrounding molecules, thereby disrupting activity in the body's cells.
The addictive ingredient of tobacco, which acts on the nervous system and is both stimulating and calming.
Nicotine replacement therapy—
A method of weaning a smoker away from both nicotine and the oral fixation that accompanies a smoking habit by giving the smoker smaller and smaller doses of nicotine in the form of a patch or gum.
Sidestream smoke—
The smoke that is emitted from the burning end of a cigarette or cigar or that comes from the end of a pipe. Along with exhaled smoke, it is a constituent of second-hand smoke.

To reduce the oral fixation supplied by a nicotine habit, a smoker can chew on licorice root (the plant, not the candy). Licorice is good for the liver, which has a major role in the body's detoxification process. Licorice also acts as a tonic for the adrenal system, which helps reduce stress. As an added incentive, if a smoker smokes a cigarette after chewing on licorice root, the cigarette tastes like burned cardboard.

Other botanicals that may help repair free-radical damage to the lungs and cardiovascular system are those high in flavonoids, such as hawthorn, gingko biloba, and bilberry, as well as antioxidants such as vitamin A, vitamin C, zinc, and selenium.


This ancient Chinese method of healing often is used to help diminish addictions, including smoking. The acupuncturist will use hair-thin needles to stimulate the body's qi, or healthy energy. Acupuncture is a sophisticated treatment system based on revitalizing qi, which supposedly flows through the body in defined pathways called meridians. According to acupuncture theory, in an individual with an addiction, qi is not flowing smoothly and needs to be unblocked.


Smoking depletes vitamin C in the body, which may leave it more susceptible to infections. Vitamin C helps to prevent or reduce free-radical damage by acting as an antioxidant in the lungs. Smokers may need Vitamin C in higher dosage than nonsmokers.

Fish in the diet supplies Omega-3 fatty acids, which are associated with a reduced risk of chronic obstructive pulmonary disease (emphysema or chronic bronchitis) in smokers. Omega-3 fats also provide cardiovascular benefits as well as an anti-depressive effect. Vitamin therapy does not reduce nicotine craving but it can help modify some of the damage created by smoking.

Public health role and response

The United States has committed massive amounts of money to public health campaigns to get people to stop smoking. One of the goals of Healthy People 2020, a set of health targets for Americans issued every ten years, is to reduce the number of smokers to 12% of the population. As of 2012, it appears unlikely that this goal will be met.

In addition to federal public health campaigns to eliminate smoking, individual states have developed anti-smoking programs. California has been one of the leaders in aggressively working to reduce the rate of smoking among its residents. Besides public health campaigns and public service announcements, many states and cities have passed strict anti-smoking ordinances that forbid smoking in public buildings such as restaurants, airports, and schools. Some of these laws have been extended to include outdoor areas such as public parks.


Aside from government activity, the marketplace reinforces the message that smoking is harmful by charging smokers more for health and life insurance. Many private companies have introduced smoking cessation programs at work as a way of reducing the cost of health care for their employees.


The best way to prevent health problems associated with smoking is to not start. However, quitting, even if one has been a heavy smoker, provides substantial health benefits. For people who already smoke, some successful aids in quitting include:

See also Asthma ; Bronchitis ; Chemical poisoning ; Chronic obstructive pulmonary disease .



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American Cancer Society, 1599 Clifton Rd., NE, Atlanta, GA, 30329, (404) 320-3333, (800) ACS-2345, .

American Lung Association, 1301 Pennsylvania Ave., NW Suite 800, Washington, DC, 20004, (212) 315-8700, (800)LUNG-USA [(800) 548-8252]

National Institute on Drug Abuse, 6001 Executive Boulevard, Room 5213, Bethesda, MD, 20892-9561, (301) 443-1124; en espanole (240) 221-4007,, .

United States Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA, 30333, (404) 639-3534, 800-CDC-INFO (800-232-4636). TTY: (888) 232-6348,, .

World Health Organization, Avenue Appia 20, 1211 Geneva 27, Switzerland, +22 41 791 21 11, Fax: +22 41 791 31 11,, .

Barbara Boughton
Revised by Tish Davidson, AM

  This information is not a tool for self-diagnosis or a substitute for professional care.