Substance Abuse

Substance abuse is the unhealthy, even dangerous, pattern of overconsuming alcohol, tobacco, illegal drugs, prescription drugs, and other substances (such as paint thinners or aerosol gasses) that change how the mind and body work. It is possible to abuse some substances without becoming physically, emotionally, or psychologically dependent on them, but continued abuse tends to make people dependent. Dependency on some substances happens very quickly and is difficult to reverse.

Substance Abuse in the United States and the World

Injected-drug use was reported in 148 countries, of which 120 report HIV infection among this population.

What Is Substance Abuse?

Substance abuse is the unhealthy, even dangerous over consumption of various substances, such as alcohol and other drugs, that usually leads to frequent serious problems at home, school, or work. People who abuse substances can get sick, ruin their relationships with other people, destroy their lives and the lives of family members, and even die; and while under the influence, they can injure or kill others. In 2015, 23.5 million people aged 12 or older needed treatment for an illicit drug or alcohol abuse problem. Substance abuse is a serious problem in the United States.

Substance abuse is not the same as occasional alcohol or other drug use. When people are addicted to a substance, they develop a strong physical or psychological need for that drug. One hallmark of addiction is tolerance, which means that over time, people need more and more of the substance to feel a high. Another symptom is withdrawal, which means that people who are addicted have physical symptoms and feel sick if they stop using the substance.

Alcohol and other drugs cause intoxication, the medical term for a temporary feeling of being high or drunk that occurs just after using a drug. Intoxication leads to changes in the way people think and act. For example, people may become angry, moody, confused, or uncoordinated. These changes increase the risk that people will make poor choices, have accidents that hurt themselves or others, or behave in a way that they will later regret.

Different substances have different effects on the body. Substances that are commonly abused in the United States include:

What Causes Substance Abuse?

People give many reasons for starting to drink alcohol or use other drugs. Some people are looking for an easy way to escape problems at home, school, or work. Others hope that alcohol or other drugs will help them fit in or make them appear to be something better than what they are. Some may use substances to “treat” or self-medicate depression or boredom. Still others are initially just curious. Whatever the original reason, no one can say for sure which people will go on to have a serious substance abuse problem. However, certain factors raise the risk that abuse will develop. Risk factors for substance abuse problems include the following:

Some of these factors can be changed or controlled by individuals themselves, but others cannot. This fact does not mean that those who come from troubled families or low-income neighborhoods are destined to become substance abusers. Certain other factors raise the odds that young people will be able to cope with problems without turning to alcohol or other drugs. These factors include the following:

Drug abuse affects almost every organ in the human body. It can cause heart disease; stroke; cancer; liver, kidney, and bone-marrow damage; HIV/AIDS; and mental illness.

Drug abuse affects almost every organ in the human body. It can cause heart disease; stroke; cancer; liver, kidney, and bone-marrow damage; HIV/AIDS; and mental illness. Methamphetamine can cause cardiac damage, elevated heart rate, and convulsions, and can also lead to diseased gums and teeth, known as “meth mouth.” Cocaine has been linked to stroke and heart attack as well as increased vulnerability to infection.
Illustration by Frank Forney. © 2016 Cengage Learning®.

Addiction is a special type of dependence in which people have a compulsive need to use the substance no matter the consequences. People who are psychologically addicted need to keep using the substance to feel satisfied. People who are physically addicted feel sick and have physical withdrawal symptoms if they stop using the substance. The risk and type of dependence varies by substance. Substance abuse occurs among people of all ages, cultures, sexes, and races.

What Are Some Commonly Abused Substances?

People abuse a wide variety of drugs, both legal and illegal. Legally available substances include alcohol, tobacco, chemicals in certain household products, over-the-counter drugs, and medicines prescribed by a doctor. Illegally sold substances include numerous street drugs.


Although moderate drinking (two to four drinks a day for men and one to two drinks a day for women and older people) is not normally considered harmful, millions of people in the United States abuse alcohol or are alcoholics (people who are physically dependent on alcohol). As of 2016 it was estimated that 17 million Americans were heavy drinkers and that 57.8 million people engaged in binge drinking (more than five drinks on a single occasion).

Alcohol affects virtually every organ in the body, and long-term use can lead to a number of medical problems. The immediate effects of drinking too much include slurred speech, poor coordination, unsteady walking, memory problems, poor judgment, and the inability to concentrate. Drinking too much alcohol at one time can cause alcohol poisoning and sudden death. The recklessness that comes from drinking too much is a leading cause of traffic accidents and other injuries. In addition, alcohol drinking by pregnant women is the cause of the most common preventable birth defect, fetal alcohol syndrome * . Long-term risks of heavy drinking include liver damage, heart disease, neurological * effects, reduced cognitive functioning, sexual problems for men, and trouble getting pregnant for women.


Tobacco contains nicotine (NIK-o-teen), a highly addictive chemical. Nicotine is readily absorbed from tobacco smoke in the lungs, whether the smoke comes from cigarettes, cigars, or pipes. Smoking is the number one cause of preventable death in the United States. The long-term health risks include cancer, lung disease, heart disease, and stroke * . Smoking by pregnant women has been linked to miscarriage * , stillbirth * , premature birth * , low birth weight * Marijuana

Marijuana (mar-ih-HWAH-nuh; nicknames: pot, herb, weed, blunts, Mary Jane) is the most widely used illegal drug. It is typically the first illegal drug tried by teenagers. It is a mixture of dried shredded flowers and leaves from the Cannabis plant. Marijuana usually is smoked in a cigarette, pipe, or water pipe, but some users also mix it with foods or use it to brew tea. Short-term effects of marijuana use include euphoria * , sleepiness, increased hunger, trouble keeping track of time, memory problems, inability to concentrate, poor coordination, increased heart rate, paranoia * , and anxiety. Long-term risks include lung disease, changes in hormone * levels, lower sperm * counts in men, and infertility.


In the United States, using and selling drugs such as cocaine and heroin is illegal, and people who break drug laws go to jail. In the Netherlands, the government has been trying a different approach that stresses treatment rather than punishment.

In the mid-1970s, the Netherlands was hit by a sharp upswing in heroin use. In response, the government launched a policy called harm reduction, which aims to lower the harmful effects of drug use for both users and other members of society. The policy is based on the belief that so-called soft drugs, such as marijuana and the related drug hashish (hah-SHESH), are less dangerous than so-called hard drugs like heroin, cocaine, amphetamines, and methamphetamine. To encourage people not to try hard drugs, the government tolerates the sale of small amounts of marijuana and hashish in adults-only coffee shops, much the way alcohol is sold in bars. Marijuana is still considered a controlled substance, but the government generally does not enforce the law regarding it.

Much debate in the early 2000s surrounded this policy and how well it was perceived to work. The number of drug addicts in the Netherlands was lower than in many countries. In addition, the average age of addicts was rising, which suggested that fewer young people were getting hooked. However, the rate of marijuana and hashish use increased, although it remained lower than in the United States. Furthermore, the policy failed to address the impact on international laws. Substances were brought into the Netherlands from and through countries where the sale and use of marijuana was strictly prohibited.


LSD is one of the most potent of all mind-altering drugs. It may be taken in the form of paper that has been dipped in the drug, or in the form of powder, liquid, gelatin, or pills. LSD can last for as long as 12 hours in the body. The physical effects of LSD include dilated (widened) pupils, increased heart rate, higher blood pressure, sweating, loss of appetite, trouble sleeping, dry mouth, and shaking. The psychological effects are much more dramatic. Users may feel several different emotions at once, or they may swing from one emotion to another, from euphoria to paranoia. They may have bizarre or terrifying thoughts, or they may see things that are not really there, such as walls melting. Some users later have flashbacks, in which they relive part of what they experienced while taking the drug, even though the drug is no longer active in their bodies. Hallucinogens are not physically addictive, but people using them are at risk of accidents, violence, panic attacks * , and other consequences of impaired judgment. All of these substances are illegal to use, make, or sell.

PCP can be snorted, smoked, or eaten. It can cause bizarre and sometimes violent behavior. Other possible effects of PCP use include increased or shallow breathing rate, high blood pressure, flushing, sweating, numbness, poor coordination, and confused or irrational thinking. High doses can lead to seeing or hearing things that are not really there, paranoia, seizures * , coma * , injuries, and suicidal behavior.


Stimulants (STIM-yoo-lunts) are drugs that produce a temporary feeling of euphoria, alertness, power, and energy. However, as the high wears off, depression and edginess set in. Stimulants include cocaine (ko-KANE; nicknames: coke, snow, blow, nose candy), crack cocaine, amphetamine (am-FET-uh-mean), methamphetamine (METH-am-FET-uh-mean; nicknames: speed, meth, crank), and crystallized methamphetamine (nicknames: ice, crystal, glass).

Percentage of U.S. high school students who ever used methamphetamines, by sex, race/ethnicity, and grade, 2013

Percentage of U.S. high school students who ever used methamphetamines, by sex, race/ethnicity, and grade, 2013
SOURCE: Centers for Disease Control and Prevention (CDC). Youth Risk Behavior Surveillance—United States, 2013. MMWR 2014; 63 (No. SS-4): 102, 106. Table by Lumina Datamatics Ltd. © 2016 Cengage Learning®.

Cocaine is a white powder that is either snorted into the nose or injected into a vein. Crack is a form of cocaine that has been chemically changed so that it can be smoked. Both forms are very addictive. Possible physical effects of cocaine and crack use include increased heart rate, high blood pressure, increased breathing rate, heart attack, stroke, trouble breathing, seizures, and a reduced ability to fight infection. Possible psychological effects include violent or strange behavior, paranoia, seeing or hearing things that are not really there, feeling as if bugs are crawling over the skin, anxiety, and depression. Eventually, cocaine addicts often lose interest in food, sex, friends, and family, and everything except getting high.

Amphetamines are human-made stimulants that speed up the central nervous system * , creating a sense of euphoria and increased energy. Amphetamines can be taken orally, injected, smoked, or sniffed. They may be legally prescribed to treat attention deficit hyperactivity disorder (ADHD), to suppress appetite, and to combat fatigue or narcolepsy (a disorder that causes uncontrolled falling asleep). Amphetamines include benzedrine, dexedrine, and methedrine. Street names for amphetamines include black beauties, crystal, hearts, bennies, crank, ice, speed, and meth.

People who abuse amphetamines need more and more of the drug to achieve the same effect or high. When they become dependent, amphetamine users may be jittery; lose weight; feel depressed, anxious, restless, and hostile; and lack energy. An overdose may cause tachycardia (TAK-ee-KAR-dee-ah), which is a very fast heartbeat, high blood pressure, seizures, fever, delirium, paranoia, psychosis * , coma, and cardiovascular collapse.


Narcotics (nahr-KOT-iks) are addictive painkillers that produce a relaxed feeling and an immediate high, followed by restlessness and an upset stomach. They can also be deadly. Drugs in this class include heroin (HAIR-oh-in; nicknames: smack, H, skag, junk), morphine (MOR-feen), opium (OH-pee-um), fentanyl (FEN-tuh-NIL), and codeine (KO-deen).

Heroin is made from morphine, a natural substance that comes from the poppy plant. It is a powder that is injected, snorted, or smoked, and it is highly addictive. Immediate effects of heroin use include a heavy feeling in the arms and legs, warm flushing of the skin, dry mouth, clouded thinking, and going back and forth between being wide awake and feeling drowsy. In addition, street heroin varies in strength, and users never know whether they are getting a particularly strong dose, or whether the heroin has been mixed with fentanyl, a much stronger drug. If users do purchase strong heroin or heroin mixed with fentanyl, they can overdose (OD) easily, resulting in coma and death. Long-term effects include collapsed veins, infection of the heart lining and valves, liver disease, and HIV*/AIDS from sharing needles.

Medicinal Marijuana

Marijuana is an illegal drug in many states. In some states, it can legally be prescribed or purchased for certain medical conditions and/or recreational purposes. Research indicates that marijuana may help in the treatment of glaucoma * , and it may relieve the nausea and wasting away that people with AIDS * and cancer * sometimes experience as a side effect of medical treatments. However, research also shows that marijuana smoke contains more tar than cigarette smoke and may contain high levels of other cancer-causing agents. Further research is needed, and public policies regarding marijuana remain controversial despite the legalization of marijuana in several states.


Inhalants are chemical vapors that can be inhaled to produce mind-altering effects. The vapors then enter the lungs. There are three types of inhalants: solvents (paint thinners, gasoline, glues, felttip-marker fluid); gases (butane lighters, whipping cream aerosols, spray paints, deodorant sprays, and nitrous oxide [“laughing gas”]); and nitrites.

The physical effects of inhalants depend on the chemical being inhaled. Many cause serious, often irreversible health problems, and sometimes cause death. Users can lose consciousness. Other serious, but potentially reversible, effects include liver damage, kidney damage, and depletion of blood oxygen. Irreversible effects of inhalants include hearing loss, loss of muscle control and limb spasms, damage to the central nervous system and brain, damage to the bone marrow * , lung damage, and heart failure.

Club drugs

Although users may think club drugs are harmless, research has shown that they can cause serious health problems and sometimes even death. When combined with alcohol, they can be particularly dangerous. Drugs in this category include MDMA (nicknames: XTC, ecstasy, Adam) GHB (nicknames: liquid ecstasy, Georgia Home Boy), Rohypnol (nicknames: roofies, roach), and ketamine (nickname: special K).

Drugs and Their Street Names

Drugs and Their Street Names
SOURCE: National Institute on Drug Abuse. “NIDA for Teens: Drug Facts.” Available at: (accessed August 20, 2015). Table by Cenveo Publisher Services. © 2016 Cengage Learning®.

MDMA combines some of the properties of hallucinogens and stimulants. Possible effects include euphoria, confusion, paranoia, increased heart rate, higher blood pressure, blurred vision, faintness, chills, and sweating. Because this drug is increasingly abused at dances, young people may forget to drink enough water, become dehydrated, and need to be rushed to the emergency room for immediate treatment. Possible psychological effects include confusion, depression, sleep problems, anxiety, and paranoia. Research has linked MDMA to long-term damage in parts of the brain that are critical for thought, memory, and pleasure.

The Opium Trade

Ancient Chinese medical texts indicated that opium, imported to the West from China by Arab traders in the 8th century, was used originally for medicinal purposes. When tobacco was introduced to China from the Philippines, the mixing of tobacco with opium became popular. British colonial traders recognized the strong demand for opium. Despite an 18th-century edict by the Chinese government banning the sale of opium and the operation of opium houses, the British continued its sale on the black market. During the late 18th century, opium was at times the largest single commodity in trade.

GHB, Rohypnol, and ketamine are often colorless, tasteless, and odorless, which makes it easy for someone to slip one of these drugs into another person's drink. As a result, these substances are sometimes called date rape drugs, because they have been used against women who were drugged unknowingly and then raped. To make matters worse, people may be unable to remember what happened to them while they were under the influence of one of these drugs.

Prescription and over-the-counter drugs

People can abuse legal medicines by taking more than prescribed, using them for nonmedical reasons, or using them to treat unrelated illnesses. The most commonly abused prescription and over-the-counter medicines are stimulants, pain relievers, depressants (such as sleeping pills), cough and cold medicines, and laxatives. According to the National Institute on Drug Abuse, the most commonly abused prescription drugs by individuals 14 years and older in the United States are: opioid pain relievers such as acetominophen and hydrocodone (Vicodin) and oxycodone hydrochloride (Oxycontin); medications used to treat ADHD like dextroamphetamine saccharate (Adderall), methylphenidate hydrochloride (Concerta), and (methylphenidate) Ritalin; and drugs classified as central nervous system depressants used in the treatment of anxiety such as diazepam (Valium) or alprazolam (Xanax).

Abusing these substances can cause physical and psychological dependence. Some prescription medications contain alcohol and narcotics (most often codeine) that are physically addicting. Combining alcohol with prescription and over-the-counter drugs, or mixing drugs, can change the effectiveness of the drugs and cause harmful side effects.

Anabolic steroids

Anabolic steroids (AN-uh-BOL-ik STER-oidz) are drugs that are related to testosterone (tes-TOS-tuh-rone), the major male sex hormone. Although these drugs have medical uses, many athletes and bodybuilders abuse them because they can increase muscle buildup with weight lifting or strength training. Although steroids may seem like a shortcut to improved sports performance and a more muscular body, they carry serious health risks. In boys and men, steroids can reduce sperm production, shrink the testicles *

Percentage of U.S. high school students who took anabolic steroids by sex, race/ethnicity, and grade, 2013

Percentage of U.S. high school students who took anabolic steroids by sex, race/ethnicity, and grade, 2013
SOURCE: Centers for Disease Control and Prevention. Youth Risk Behaviour Surveillance—United States, 2013, MMWR 2014; 63 (No. SS-4): 108. Table by Lumina Datamatics Ltd. © 2016 Cengage Learning®.

What Are Some Other Risks of Substance Abuse?

Abusing drugs leads to unclear thinking and unpredictable behavior. Many drugs also cause poor coordination and slow reflexes. In the United States, substance abuse is a major factor in the spread of infection with HIV (human immunodeficiency virus), the virus that causes AIDS. It is a direct cause because many types of drugs are injected into the veins, and people can spread HIV by using or sharing unclean needles. It is also an indirect cause because people whose thinking is clouded by alcohol or other drugs are more likely to have unsafe sex, which increases their risk of contracting HIV from an infected partner.

How Do Doctors Diagnose and Treat Substance Abuse?


Substance abuse often is difficult to diagnose and treat. Doctors can screen for substance abuse through a medical history, a physical exam, and sometimes blood or urine testing, but doctors and family members often have a hard time convincing substance abusers that they need help. In many cases, substance abusers are more afraid of losing the drug and of withdrawal symptoms than of the health and safety consequences of continued use.


Treatment for substance abuse consists of helping people stop using the substance, treating withdrawal symptoms, and preventing people from returning to substance abuse afterwards. Outpatient * psychotherapy *

  • Evaluate substance abusers for coexisting psychiatric or medical disorders
  • Teach them about the effects of the drug and their addiction
  • Offer mutual support and self-help groups
  • Provide individual and group psychotherapy
  • Offer a replacement for the substance being given up
  • Emphasize behavior changes that promote abstinence from the substance
  • Offer rehabilitation and life skills training

Even people who are successfully treated must guard against reusing the abused substance. People with serious medical or psychiatric symptoms, people who overdose on drugs, and people who have toxic reactions to drugs require immediate medical treatment.

See also Addiction • AIDS and HIV Infection • Alcoholism • Delusions, Delusional Disorders, and Paranoia • Hallucination • Infection • Lung Cancer • Poisoning • Pregnancy • Prematurity • Psychopharmacology • Seizures • Sports Injuries: Overview • Stroke • Stupor and Coma • Tobacco-Related Diseases: Overview


Books and Articles

Sheff, David. Clean: Overcoming Addiction and Ending America's Greatest Tragedy. New York: Eamon Dolan/Mariner Books, 2014.

Williams, Rebecca E. and Julie S. Kraft. The Mindfulness Workbook for Addiction: A Guide to Coping with the Grief, Stress, and Anger that Trigger Addictive Behaviors. Oakland, CA: New Harbinger Publications, 2012.


Centers for Disease Control and Prevention. “Alcohol and Public Health.” (accessed July 13, 2016).

MedlinePlus. “Drug Abuse.” U.S. National Library of Medicine. (accessed July 13, 2016).

National Institute on Drug Abuse. “DrugFacts: Understanding Drug Abuse and Addiction.” (accessed July 13, 2016).

Substance Abuse and Mental Health Services Administration. “Behavioral Health Treatment Services Locator.” (accessed July 13, 2016).


Alcoholics Anonymous. Grand Central Station, PO Box 459, New York, NY 10163. Telephone: 212-870-3400. Website: (accessed July 13, 2016).

National Council on Alcoholism and Drug Dependence. 217 Broadway, Suite 712, New York, NY 10007. Telephone: 212-269-7797. Website: (accessed July 13, 2016).

National Institute on Alcohol Abuse and Alcoholism. 5635 Fishers Ln., MSC 9304, Bethesda, MD 20892-9304. Toll-free: 888-696-4222. Website: (accessed July 13, 2016).

National Institute on Drug Abuse. 6001 Executive Blvd., Rm. 5213, Bethesda, MD 20892-9561. Telephone: 301-443-1124. Website: (accessed July 13, 2016).

Substance Abuse and Mental Health Services Administration (SAMHSA). 1 Choke Cherry Rd., Rockville, MD 20847-2345. Toll-free: 877-SAMHSA-7. Website: (accessed July 13, 2016).

* self-esteem is the value that people put on the mental image that they have of themselves.

* fetal alcohol syndrome, which occurs if the fetus is exposed to alcohol, is a condition that is associated with mental, physical, and behavioral differences. Oppositional behavioral problems, learning difficulties, intellectual disability, and stunted growth can occur in the children of women who drink alcohol while they are pregnant.

* neurological (nur-a-LAH-je-kal) refers to the nervous system, which includes the brain, spinal cord, and the nerves that control the senses, movement, and organ functions throughout the body.

* stroke is a brain-damaging event usually caused by interference with blood flow to the brain.

* miscarriage (MIS-kar-ij) is the end of a pregnancy through the death of the embryo or fetus before birth.

* stillbirth is the birth of a dead fetus.

* premature birth (pre-ma-CHUB) means born too early. In humans, it means being born after a pregnancy lasting less than 37 weeks.

* low birth weight means born weighing less than normal. In humans, it refers to a full-term (pregnancy lasting 37 weeks or longer) baby weighing less than 5 pounds.

* euphoria (yoo-FOR-ee-uh) is an abnormally high mood with the tendency to be overactive and overly talkative, and to have racing thoughts and overinflated self-confidence.

* paranoia (par-a-NOY-a) refers to either an unreasonable fear of harm by others (delusions of persecution) or an unrealistic sense of self-importance (delusions of grandeur).

* hormone is a chemical substance that is produced by a gland and sent into the bloodstream carrying messages that affect other parts of the body.

* sperm are the tiny, tadpolelike cells males produce in their testicles. Sperm can unite with a female's egg to result in conception.

* panic attacks are periods of intense fear or discomfort with a feeling of doom and a desire to escape. During a panic attack, a person may shake, sweat, be short of breath, and experience chest pain.

* seizures (SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.

* coma (KO-ma) is an unconscious state like a very deep sleep. A person in a coma cannot be awakened, and cannot move, see, speak, and may not be able to hear.

* central nervous system (SEN-trul NER-vus SIS-tem) is the part of the nervous system that includes the brain and spinal cord.

* psychosis (sy-KO-sis) refers to mental disorders in which the sense of reality is so impaired that a patient cannot function normally. People with psychotic disorders may experience delusions (exaggerated beliefs that are contrary to fact), hallucinations (something that a person perceives as real but that is not actually caused by an outside event), incoherent speech, and agitated behavior, but they usually are not aware of their altered mental state.

* HIV, or human immunodeficiency virus (ih-myoo-no-dih-FIHshen-see), is the virus that causes AIDS (acquired immunodeficiency syndrome).

* glaucoma is a group of disorders that cause pressure to build in the eye, which may result in vision loss.

* AIDS, (or Acquired Immunodeficiency (ih-myoo-no-dih-FIH-shen-see) Syndrome, is an infection that severely weakens the immune system; it is caused by the human immunodeficiency virus (HIV).

* cancer is a condition characterized by uncontrolled growth of abnormal cells leading to a growth or tumor, which may be fatal.

* bone marrow is the soft tissue inside bones where blood cells are made.

* testicles (TES-tih-kulz) are the paired male reproductive glands that produce sperm.

* outpatient refers to a medical procedure that is conducted in a doctor's office or hospital for treatment but does not require an overnight stay in a hospital bed.

* psychotherapy (sy-ko-THER-a-pea) is the treatment of mental and behavioral disorders by support and insight to encourage healthy behavior patterns and personality growth.

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