Heroin

The brand name under which the pharmaceutical company Bayer sold diacetylmorphine. Heroin (diacetylmorphine) is an acetylated form of morphine. In the body, it breaks down into morphine and 6-acetylmorphine (6AM).

Heroin is a prescription medication in the UK where it is used as a pain medication.
Heroin was once thought to be less addictive than morphine.