heroin

heroin, highly addictive morphine derivative that makes up a large portion of the illicit traffic in narcotics. Heroin is classified as an opioid depressant, a category of psychoactive drugs that slow central nervous system activity while producing analgesia (pain relief) and euphoria.

Heroin is made by treating morphine with acetic anhydride; the resulting substance is four to eight times as potent as morphine. (Morphine is an alkaloid found in opium, which is the dried milky exudate obtained from the unripe seedpods of the poppy plant.)

Heroin was first synthesized from morphine by a British chemist in 1874 and was introduced as a commercial product by the Bayer Company of Germany in 1898; it was originally used as a narcotic analgesic, but its undesirable side effects were found to far outweigh its value as a pain-killing drug, and there are now strict prohibitions on its use in many countries. In the United States, for example, narcotics such as heroin are regulated under the Controlled Substances Act, which established a classification system with five schedules to identify drugs based on their potential for abuse, their applications in medicine, and their likelihood of producing dependence. The act is implemented by the Drug Enforcement Administration, which is empowered to prosecute violators of laws governing these controlled substances.

Britannica Quiz

A Visit with the Word Doctor: Medical Vocabulary Quiz

Physiological effects

Heroin constricts the user’s pupils, slows respiration, heartbeat, and gastrointestinal activity, and induces sleep. Among those addicted to it, however, heroin’s most valued effect is the ecstatic reaction that it gives after being intravenously injected; within seconds a warm, glowing sensation spreads over the body. This brief but intense rush is then followed by a deep, drowsy state of relaxation and contentment that is marked by a clouding of consciousness and by poor concentration and attention. This state lasts two to four hours and then gradually wears off. Some individuals do react negatively to heroin, experiencing only anxiety, nausea, and depression. Heroin exerts these effects by binding to opioid receptors in the brain, mimicking naturally occurring endorphins and altering neurotransmission in regions involved in pain perception and reward.

Heroin in powder form can be sniffed, or inhaled. When dissolved in water, it can be injected subcutaneously (skin-popping) or intravenously (mainlining). But heroin addicts, as opposed to novice users of the drug, almost invariably inject it intravenously, because this produces the most rapid and intense euphoric effects.

Heroin dependence and addiction

A person who has developed heroin dependence, in which the body has physiologically adapted to and can function only in the presence of the drug, must usually inject heroin about twice a day in order to avoid the discomfort of withdrawal symptoms; these include restlessness, body aches, insomnia, nausea, vomiting, and diarrhea. An individual who is trying to break the body’s dependence on heroin must undergo an intense withdrawal period lasting three or four days, with symptoms lessening markedly thereafter.

Explore Britannica Premium!

The trusted destination for professionals, college students, and lifelong learners.

SUBSCRIBE

An important characteristic of heroin dependence is the development of a high tolerance to the drug, causing individuals to use the drug more often or in greater amounts to achieve the desired euphoric effects. For individuals in heroin maintenance or recovery programs, as dependence on the drug lessens and eventually disappears, tolerance also declines and eventually disappears, even in the case of very heavy use.

Nonetheless, for many heroin users, addiction remains. Addiction is a chronic condition characterized by altered brain chemistry, particularly in reward pathways, that results in intense cravings, compulsive drug-seeking behavior, and continued drug use, while ignoring negative consequences. Behavioral and emotional changes frequently include neglect of responsibilities, impaired judgment, mood imbalances, and social withdrawal. In addition, heroin addiction is expensive to maintain, and those affected, when not gainfully employed or when assets or other sources of money become depleted, find other ways to support their habit. Some examples of ways in which individuals may fund their addiction include borrowing money from friends and family under false pretenses and engaging in criminal activity, prostitution, identity theft and fraud, and drug peddling. Individuals with heroin addiction—or opioid addiction more generally—contribute significantly to criminal activity, often committing a disproportionately large share of offenses in countries where drug use is problematic.

Heroin illegally available on the street is of varying purity, anywhere from 1 to 100 percent. More dilute versions of the drug are produced by mixing it with baking soda, quinine, starch, sugar, or other substances. Especially dangerous combinations include the use of rat poison or the narcotic drug fentanyl. The unwitting injection of relatively pure heroin is a major cause of heroin overdose, the main symptoms of which are extreme respiratory depression deepening into coma and then into death. Aside from this danger, individuals with heroin addiction are prone to hepatitis and other infections stemming from their use of dirty or contaminated syringes; scarring of the surfaces of the arms or legs is another common injury, because of repeated needle injections and subsequent inflammation of surface veins.

Heroin addiction first appeared in the early 20th century, and for several decades thereafter it was customarily confined to the marginal or criminal elements in Western societies. But from the 1960s on its use spread to youths in middle- and upper-income families and to populations in less-developed regions. Heroin use and trafficking are worldwide problems, and both national and international law enforcement and regulatory agencies seek to control and suppress those activities. The private use and possession of heroin is illegal in most countries, although the drug may be used as a painkiller for terminal cancer patients and others who are affected by severe pain. Most illegally distributed heroin comes from opium produced in the Middle East, Southeast Asia, and Mexico. In the 21st century, the leading opium-producing countries included Afghanistan and Myanmar (Burma).