Substance addiction

Abuse of substances such as alcohol, marijuana, cocaine, prescription medications, and others can cause health issues and serious problems with family, friends, coworkers, job, money, and the law. Yet despite these problems, use of the substance continues.

Why? Addiction is a physical dependence on a chemical substance. The dependence leads to unpleasant symptoms, called withdrawal, when a person stops using the substance. People often begin using an addicting substance because it initially gives them pleasure. By the time addiction has developed, the pleasure is often gone. The driving force behind continued use is a need to avoid the unpleasant symptoms of withdrawal.

Addiction has a strong hereditary component. Children raised apart from their alcoholic biological parents, for example, have four times the risk of becoming alcoholics than the general population.

This means that different people have different susceptibilities to becoming addicted. Why one person can have a drink or two each day and not become addicted to alcohol, whereas another becomes addicted, is a mystery. People with a tendency to become addicted to one substance also have a tendency to become addicted to others.

Environmental factors such as physical and sexual abuse, or disadvantaged social status, play an important role in addiction. Even so, people from all walks of life are vulnerable to addiction.

While addiction leads to personality changes over time, there are no specific personality characteristics that predict a person will develop addictive behaviors.

The most common addictions involve the use of alcohol, tobacco, other legal and illegal drugs, and other mood-altering substances. The use of these substances may be physically and psychologically harmful to the user, and may also lead to antisocial behavior. Antisocial behavior can lead to crime, which can occur both when a person is high on a substance or fighting withdrawal and needs money to obtain the substance to which he or she is addicted.

Depression is unusually common in people who engage in substance abuse.


Most people follow one of three patterns of alcohol abuse:

  • they drink and become intoxicated daily
  • they drink at specific but predictable times
  • they stop drinking for extended periods that end in binges of constant drinking that can last for several days, weeks, or months.

Chronic alcoholism is a progressive disease that develops in stages, usually beginning between the ages of 20 and 40.

The first stage involves using alcohol to relieve tension. It is during this time that a physical dependence on the drug begins. During the second stage, the person becomes more and more preoccupied with obtaining alcohol. He or she may lose control when drinking, suffer blackout, or forget alcohol-related events.

In the third stage, behavior and personality changes start to take place. These include aggressive behavior and a complete lack of insight into the problem. Finally, in the late stage, persistent use of alcohol affects the person's physical and emotional health, causing serious deterioration in ability to function.

Physical complications can include inflammation of the stomach, inflammation of the liver, permanent nerve and brain damage (forgetfulness, blackouts, or problems with short-term memory), and inflammation of the pancreas.

Long-term abuse of alcohol can increase the risk and severity of pneumonia and tuberculosis; can damage the heart, leading to heart failure; and can cause cirrhosis of the liver, leading to liver failure.

Alcohol intoxication is a major cause of motor vehicle collisions and other injuries, often with fatal consequences. Alcohol consumption by pregnant women can cause fetal alcohol syndrome, which can cause mental retardation.

Withdrawal from alcohol carries its own risks, including restlessness, agitation, hallucinations, delirium, and seizures. In its most severe form, alcohol withdrawal can be life-threatening and require hospitalization.


Smoking cigarettes, cigars, or pipes, chewing tobacco, or using snuff can quickly lead to nicotine addiction. About 45 million people in the United States use nicotine in some form. More than half of smokers light their first cigarette within a half hour of waking up, and 30% have never stopped smoking for as long as a week.

Most tobacco users wish they had never started; only 5% succeed in quitting on the first attempt, and only 3% to 5% are able to stay away from tobacco for a year. Nicotine is one of the most addictive of all drugs. The addiction develops quickly and lasts a long time. Drug addicts say it is easier to give up cocaine and heroin than to stop smoking.

In our society, it is easier for people to become dependent on tobacco than virtually any other drug. Compared to other addicting substances, tobacco is relatively inexpensive, easily available, and socially acceptable (though that is changing).

Nicotine does not make you high, so it does not interfere with your ability to function. Tobacco users quickly become tolerant of any unpleasant effects, such as bad taste or odor. The cigarette is a highly effective drug-delivery device. Nicotine goes straight to the lungs, where it is absorbed by the blood, sent to the heart, and pumped into the arteries and the brain. The habit is performed regularly and often—at a pack a day, 75,000 puffs a year—thereby reinforcing the behavior.

There are good reasons not to use tobacco or to quit. Tobacco accounts for about 1 of 7 deaths in the United States, 1 of 3 between the ages of 35 and 70. Smoking causes chronic bronchitis and emphysema. Women who smoke during pregnancy have a higher rate of miscarriage.

Tobacco use greatly increases the risk of cancers of the lung, lip, tongue, throat, cheek, esophagus, cervix, and bladder.

Smoking raises blood pressure, makes blood clot too easily, reduces the heart's oxygen supply, and damages the walls of arteries. That's why smoking leads to more deaths from heart disease than from smoking-related cancers.

Treatment options

Support groups such as 12-step programs are considered a mainstay for treating many forms of substance use. Participants attend a program based on frequent, regular meetings with others who share the problem and are urged to be honest in describing their problems. Members of the group look to each other for support and for ideas about how to deal with their problems.

Most support groups are not run by health professionals. For this reason, there are few research studies evaluating their effectiveness. However, 12-step programs have existed for many years, clearly have helped many people, and are encouraged by most professionals as part of the treatment of addictions, along with a combination of supportive and behavioral psychotherapy.

There are also growing numbers of medicines that are helpful in overcoming addiction to tobacco, alcohol, and drugs such as opioids.


As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Sign Up
Harvard Health Publishing Logo

Thanks for visiting. Don't miss your FREE gift.

The Best Diets for Cognitive Fitness, is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School

Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health, plus the latest advances in preventative medicine, diet and exercise, pain relief, blood pressure and cholesterol management, and more.

Harvard Health Publishing Logo

Health Alerts from Harvard Medical School

Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss...from exercises to build a stronger core to advice on treating cataracts. PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.

BONUS! Sign up now and
get a FREE copy of the
Best Diets for Cognitive Fitness

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness.