Heroin (diacetylmorphine) is derived from the morphine alkaloid found in opium and is roughly 2-3 times more potent. A highly addictive drug, heroin exhibits euphoric ("rush"), anxiolytic and analgesic central nervous system properties. Heroin is classified as a Schedule I drug under the Controlled Substances Act of 1970 and as such has no acceptable medical use in the United States. Pure heroin is a white powder with a bitter taste. Most illicit heroin is sold as a white or brownish powder and is usually "cut" with other drugs or with substances such as sugar, starch, powdered milk, or quinine. It can also be cut with strychnine or other poisons. Because heroin abusers do not know the actual strength of the drug or its true contents, they are at risk of overdose or death. Another form of heroin known as "black tar" may be sticky, like roofing tar, or hard, like coal. Its color may vary from dark brown to black.
Heroin is metabolized to morphine and other metabolites which bind to opioid receptors in the brain. The short-term effects of heroin abuse appear soon after a single dose and disappear in a few hours. After an injection of heroin, the user reports feeling a surge of euphoria (the "rush") accompanied by a warm flushing of the skin, a dry mouth, and heavy extremities. Following this initial euphoria, the user experiences an alternately wakeful and drowsy state. Mental functioning becomes clouded due to the depression of the central nervous system. Other effects that heroin may have on users include respiratory depression, constricted ("pinpoint") pupils and nausea. Effects of heroin overdose may also include slow and shallow breathing, hypotension, muscle spasms, convulsions, coma, and possible death.
