drug addiction, a condition characterized by an overwhelming desire to continue taking a drug to which one has become habituated through repeated consumption because it produces a particular effect, usually an alteration of mental status. Addiction is usually accompanied by a compulsion to obtain the drug, a tendency to increase the dose, a psychological or physical dependence, and detrimental consequences for the individual and society. Common addictive drugs are barbiturates, alcohol, and morphine and other opioids, especially heroin, which has slightly greater euphorigenic properties than other opium derivatives. See also alcoholism, drug abuse.
