Heroin is a semi-synthetic drug synthesized from morphine, a derivative of the opium poppy. Other drugs derived from the opium poppy (opiates) are codeine and morphine.

Opium is the dried latex obtained from opium poppies. Opium contains up to 12% morphine, which is the drug from which heroin was developed by the German drug maker, Bayer, in 1895.

Heroin and opiates are used as painkillers and recreational drugs. Opiates are highly addictive, especially heroin. Tolerance builds quickly to moderate physical dependence and severe psychological dependence.

Heroin is internationally controlled and is an illegal substance with few exceptions worldwide.