Drug is any substance (with the exception of food and water) which, when taken into the body, alters the body’s function either physically and/or psychologically. Drugs may be legal (e.g. alcohol, caffeine and tobacco) or illegal (e.g. cannabis, ecstasy, cocaine and heroin).
Psychoactive drugs affect the central nervous system and alter a person’s mood, thinking and behaviour. Psychoactive drugs may be divided into four categories: depressants, stimulants, hallucinogens and ‘other’.