These may be for fun or excitement; to feel good, better or different; to counteract negative feelings; because they are bored or curious; because their friends or family do it; or because they have a dependence on the drug. Often people who use drugs associate with other people who use drugs. It is not always clear which comes first— the friends or the drugs.
Drugs that affect a person's mental state, whether prescribed for a medical condition or taken for recreational purposes, are called psychoactive drugs.