drug

A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function.[3] There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.[4]
In pharmacology, a drug is "a chemical substance used in the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental well-being."[4] Drugs may be prescribed for a limited duration, or on a regular basis for chronic disorders.[5]
Recreational drugs are chemical substances that affect the central nervous system, such as opioids or hallucinogens.[5] They may be used for perceived beneficial effects on perception, consciousness, personality, and behavior.[5][6] Some drugs can cause addiction and habituation.[6]
Drugs are usually distinguished from endogenous biochemicals by being introduced from outside the organism.[citation needed] For example, insulin is a hormone that is synthesized in the body; it is called a hormone when it is synthesized by the pancreas inside the body, but if it is introduced into the body from outside, it is called a drug.[citation needed]
Many natural substances such as beers, wines, and some mushrooms, blur the line between food and drugs, as when ingested they affect the functioning of both mind and body.