Morphine: A highly addictive substance derived from opium that is particularly effective in relieving pain.

Tolerance: The adjustment that the brain and the body make to the regular use of certain drugs so that ever larger doses are needed to achieve the earlier effects.

Barbiturates: One group of sedative-hypnotic drugs that reduce anxiety and help produce sleep.

Delirium tremens (DTs): A dramatic withdrawal reaction experienced by some people with alcohol use disorder. It consists of confusion, clouded consciousness, and terrifying visual hallucinations.

Korsakoff’s syndrome: An alcohol-related disorder marked by extreme confusion, memory impairment, and other neurological symptoms.

Heroin: One of the most addictive substances derived from opium.

Sedative-hypnotic drug: A drug used in low doses to calm people and in higher doses to help people sleep. Also called an anxiolytic drug.

Substance use disorder: A pattern of maladaptive behaviors and reactions brought about by repeated use of a substance, sometimes also including tolerance for the substance and withdrawal reactions.

Endorphins: Neurotransmitters that help relieve pain and reduce emotional tension. They are sometimes referred to as the body’s own opioids.

substance intoxication: A cluster of temporary undesirable behavioral or psychological changes that develop during or shortly after the ingestion of a substance.

Free-basing: A technique for ingesting cocaine in which the pure cocaine basic alkaloid is chemically separated from processed cocaine, vaporized by heat from a flame, and inhaled through a pipe.

Withdrawal: Unpleasant, sometimes dangerous reactions that may occur when people who use a drug regularly stop taking or reduce their dosage of the drug.

Opium: A highly addictive substance made from the sap of the opium poppy seed.

Fetal alcohol syndrome: A cluster of problems in a child, including low birth weight, irregularities in the hands and face, and intellectual deficits, caused by excessive alcohol intake by the mother during pregnancy.

Benzodiazepines: The most common group of antianxiety drugs, which includes Valium and Xanax.

Cocaine: An addictive stimulant obtained from the coca plant. It is the most powerful natural stimulant known.

Alcohol: Any beverage containing ethyl alcohol, including beer, wine, and liquor.

Crack: A powerful, ready-to-smoke freebase cocaine.

Opioid: Opium or any of the drugs derived from opium, including morphine, heroin, and codeine.

Reward center: A dopamine-rich pathway in the brain that produces feelings of pleasure when activated.

Tetrahydrocannabinol (THC): The main active ingredient of cannabis.

Synergistic effect: In pharmacology, an increase of effects that occurs when more than one substance is acting on the body at the same time.

cannabis drugs: Drugs produced from the varieties of the hemp plant Cannabis sativa. They cause a mixture of hallucinogenic, depressant, and stimulant effects.

Hallucinogen: A substance that causes powerful changes primarily in sensory perception, including strengthening perceptions and producing illusions and hallucinations. Also called a psychedelic drug.

Alcoholics Anonymous (AA): A self-help organization that provides support and guidance for people with alcoholism.

Methadone maintenance program: An approach to treating heroin-centered substance use in which clients are given legally and medically supervised doses of a substitute drug, methadone.

Antagonist drugs: Drugs that block or change the effects of an addictive drug.

Methamphetamine: A powerful amphetamine drug that has experienced a surge in popularity in recent years, posing major health and law enforcement problems.

Gambling disorder: A disorder marked by persistent and recurrent gambling behavior, leading to a range of life problems.

Aversion therapy: A treatment in which clients are repeatedly presented with unpleasant stimuli while performing undesirable behaviors such as taking a drug.

Detoxification: Systematic and medically supervised withdrawal from a drug.

LSD (lysergic acid diethylamide): A hallucinogenic drug derived from ergot alkaloids.

Residential treatment center: A place where people formerly addicted to drugs live, work, and socialize in a drug-free environment. Also called a therapeutic community.

Relapse-prevention training: A cognitive-behavioral approach to treating alcohol use disorder (and applied to certain other disorders) in which clients are taught to keep track of their drinking behavior, apply coping strategies in situations that typically trigger excessive drinking, and plan ahead for risky situations and reactions.

amphetamine: A stimulant drug that is manufactured in the laboratory.

Marijuana: One of the cannabis drugs, derived from the buds, leaves, and flowering tops of the hemp plant Cannabis sativa.

Internet gaming disorder: A disorder marked by persistent, recurrent, and excessive Internet gaming activity. Recommended for further study by the DSM study group.