Heroin molecule. Computer artwork of a molecule of heroin (diamorphine). Atoms are represented as spheres and are colour-coded: carbon (light grey), hydrogen (dark grey) and oxygen (red). Heroin is a powerful narcotic (stupor inducing) and analgesic (painkiller) that is derived from morphine. Its use in medicine is restricted because it is highly addictive after only a short period of use. Heroin is abused as a recreational drug. The body develops tolerance to the drug quickly and larger doses are needed to achieve the same effect.