Heroin, or diacetylmorphine is an opioid analgesic that is classified in most countries in the schedule of drugs that have no medical benefit and high potential for abuse. It is medically prescribed to treat the most severe heroin addicts in a few countries now. The first research comes from the UK where psychiatrists have been able for a long time to prescribe heroin. In recent years, several countries have carried out trials with prescribed heroin as a form of substitution treatment for severely addicted patients. Switzerland and the Netherlands have concluded the trials and published the results. The main finding of both studies was that for severely addicted, older, heroin users methadone plus heroin was more effective than treatment with methadone alone. Similar studies are being currently carried out in Germany and in the Andalucia and Catalunya regions in Spain..

One of the major advantages of diamorphine over some of the other opioid treatments is its ability to attract into treatment those people who cannot or will not otherwise get into treatment. A main disadvantage is that it has a short half-life and patients need to be medicated with heroin several times a day thus making it an expensive and inconvenient form of treatment.