Heroin. Computer graphic of a molecule of heroin (diacetylmorphine or diamorphine), a pain-killing (analgesic) drug. Heroin was first synthesised in 1898 from morphine, an alkaloid drug obtained from the opium poppy, Papaver somniferum. Used in some countries to relieve severe pain, heroin's side effects include addiction, constipation, drowsiness, and respiratory depression. Heroin is widely used as a recreational drug for the psychological high" it induces, despite laws prohibiting its use and the dangers of addiction."