Heroin (diacetylmorphine) is a controlled narcotic drug and analgesic, manufactured from opium within the poppy plant as a semi-synthetic opioid. The term 'heroin' was trademarked in the early 1900s for the drug, and is now the most commonly used street term for the chemical, which is otherwise known as diamorphine, particularly when used in a medical context. The opium poppy has been cultivated for its properties since at least 3400 BC (in Mesopotamia).
Heroin was briefly commercially marketed as a cough medicine for children, and as substitute for medicinal morphine, having been erroneously believed to be less addictive. Heroin actually metabolizes into morphine in the bloodstream. It is very effective at relieving pain, but it is extraordinarily dangerous and addictive in the form most often sold on the street. there is also the significant risk of contracting HIV or other blood borne diseases if needles are shared as well as normal infections if the needle used is not sterile. Even more dangerous than heroin are it's chemically altered derivative "designer drug" versions. Some of these ultra-potent variations have been known to cause users to overdose without being able to remove the needle first.
Apart from medicinal use under strict control, heroin is illegal nearly worldwide, with harsh penalties for its possession, manufacture and trafficking, including the death penalty in many countries.
Administration of heroin is typically conducted intravenously (sometimes mixed with cocaine, a combination known as a 'speedball'), insufflated, or smoked (referred to colloquially as 'chasing the dragon'). Large doses of heroin can be fatal.