Heroin

Heroin, also known as diamorphine or diacetylmorphine, is a semi-synthetic opioid. It is the 3,6-diacetyl derivative of morphine (hence diacetylmorphine). The white crystalline form is commonly the hydrochloride salt, diacetylmorphine hydrochloride. It mimics endorphins and thus causes a high sense of well-being when entered into the bloodstream (usually through injection). For this reason it can be used both as a pain-killer and a recreational drug. It has a high addiction potential, and frequent administration may cause a rapid development of tolerance by the user, especially when compared to other substances, though occasional use may not lead to symptoms of withdrawal.

Internationally, heroin is controlled under Schedules I and IV of the Single Convention on Narcotic Drugs.

It is illegal to manufacture, possess, or sell heroin in the United States; however, under the name diamorphine, heroin is a legal prescription drug in the United Kingdom.

The text above is an edited version of the Wikipedia article on Heroin: http://en.wikipedia.org/wiki/Heroin