Heroin Toxicity

Updated: Dec 31, 2020
  • Author: Rania Habal, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Practice Essentials

Heroin remains one of the most frequently abused narcotics in the United States. It may be injected intravenously ("mainlining"), or subcutaneously (“skin-popping). It also can be ingested, snorted, or smoked. The presence of impurities may limit its absorption through mucous membranes, thus limiting its "rush" and "high" when sniffed or snorted.

Heroin poisoning occurs most commonly when an individual unintentionally overdoses on the drug. Poisoning may also occur in a "body packer," "body pusher," or "body stuffer." Body packers, also called "mules," are people who swallow and pack their GI tracts with bags of heroin in order to smuggle the illegal drug from one country to another. Body pushers conceal the drugs in their rectum and/or vagina. In both of these groups, the drugs are carefully packaged for safe passage, but poisoning occurs if the packages rupture. Body packing or pushing should be suspected in persons who are found unconscious at airports, during international flights, or soon after a trip to endemic countries.

Body stuffers, on the other hand, are people who ingest all the drugs in their possession in order to conceal the evidence from the police. Because these packages are typically not designed for safe GI transport, they easily rupture and frequently cause poisoning.



Heroin (diacetylmorphine) is a semisynthetic narcotic derived from the opium poppy Papaver somniferum. It was first synthesized in 1874 and was originally marketed as a safer, nonaddictive substitute for morphine. Soon after its introduction, heroin was realized to be clearly as addictive as morphine, prompting the US government to institute measures to control its use. By 1914, the Harrison Narcotics Act prohibited the use of heroin without a prescription. In 1920, the Dangerous Drugs Act prohibited the use of heroin altogether, thus driving it underground.

Afghanistan remains the world's largest cultivator of opium, accounting for approximately 84% of the world's opium poppy cultivation. Myanmar is the second largest, at 7%, and Mexico is the third largest, at 6%. Mexico, Colombia, Guatemala, and other Latin American countries are the main suppliers of opium products to North America. [1]

In its pure form, heroin is a white powder with a bitter taste. However, samples are frequently mixed with other substances so dealers can maximize their profits. Because of these impurities and additives, street heroin samples have different purities and may appear in various hues, ranging from white to dark brown. Heroin is occasionally sold as a black, tarry substance, especially when crude processing methods are used to manufacture it. Heroin samples from South America appear to have the highest purity, reaching at times more than 70% purity.



Heroin is a highly addictive semisynthetic opioid that is derived from morphine. When used intravenously, it is three to five times more potent than its parent compound and is able to modulate pain perception and cause euphoria. Similar to morphine, heroin and its metabolites have mu, kappa, and delta receptor activity. In general, stimulation of the mu receptors results in analgesia, euphoria, CNS depression, respiratory depression, and miosis. Stimulation of the delta and kappa receptors also results in analgesia, but the kappa receptors are mostly involved in spinal analgesia. [2]

Heroin, similar to morphine and other narcotics, reduces the brain's responsiveness to changes in carbon dioxide levels and hypoxia, thus resulting in respiratory depression. It also reduces peripheral vascular resistance (resulting in mild hypotension), causes mild vasodilation of the cutaneous blood vessels (resulting in flushing), and stimulates histamine release (resulting in pruritus). [2]

Heroin's inhibitory effects on baroreceptor reflexes result in bradycardia, even in the face of hypotension. [2]

Finally, heroin decreases gastric motility, inhibits the effect of acetylcholine on the small intestine, and diminishes the colonic propulsive waves, resulting in prolongation of gastric emptying time by as much as 12 hours, with consequent constipation in habitual users. [2]

The onset of action, peak effects, and duration of action vary with the different methods of heroin use. Onset of action occurs within 1-2 minutes with intravenous injection and within 15-30 minutes with intramuscular injection. Heroin's peak therapeutic and toxic effects are generally reached within 10 minutes with intravenous injection, within 30 minutes with intramuscular injection or when snorted, and within 90 minutes when injected subcutaneously. Analgesic effects generally last 3-5 hours. [2]

Intravenously injected heroin creates a rush, or a sensation of intense pleasure, that begins within 1 minute of the injection and lasts from 1 minute to a few minutes. This rush is followed by a period of sedation that lasts about an hour. The initial rush is likely due to heroin's high lipid solubility and rapid penetration to the brain. The half-life of heroin is 15-30 minutes. [2]

Heroin is rapidly converted to 6-monoacetylmorphine (6-MAM) by the liver, brain, heart, and kidneys and may not be detected in the blood at the time of blood draw. 6-MAM is then converted to morphine. Morphine is metabolized by the liver and excreted as a glucuronide product or in its free form by the kidneys. Morphine's half-life is considerably longer than heroin's (ie, 2-3 h). A small amount of unchanged 6-MAM is excreted in the urine for up to 24 hours after heroin use. Because 6-MAM can originate only from heroin, its detection in the urine can mean only that the patient used either heroin or 6-MAM. [2]



United States

The true prevalence of heroin use is probably much higher than reported in surveys because surveys depend on self-reporting and may not reach some of the persons who use heroin the heaviest. According to the US Substance Abuse and Mental Health Services Administration (SAMHSA) 2016 National Survey on Drug Use and Health (NSDUH), approximately 948,000 persons aged 12 years and older reported using heroin in the past year (about 0.4% of that age group); about 475,000 persons (about 0.2%) were current heroin users, and about 591,000 persons had a heroin use disorder. [3]

NSDUH estimates that the percentage of current heroin users in 2016 were higher than the percentages from 2002 to 2013, but was similar to the percentages in 2014 and 2015. [3]  The Centers for Disease Control and Prevention (CDC) estimates that the number of persons who used heroin in the past year decreased from 886,000 in 2017 to 808,000 in 2018. [4]


According to the 2020 report of the United Nations Office on Drug and Crime (UNODC), the global prevalence of opiate (heroin, opium, and misused pharmaceutical opioids) use in 2018 was estimated at 1.2% of the population, or 57.8 million people. Levels of opiate use were much higher than the global average in North America (3.6%), Australia and New Zealand (3.3%), the Near and Middle East and South-West Asia (2.6%) and South Asia (2.0%). [1]

In its 2020 annual report, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) estimated that in 2018 there were 1.3 million high-risk opioid users in Europe, or 0.4 % of the adult population, with heroin being the most widely used opioid. The EMCDDA reported that although patterns and trends vary among countries, Europe may be witnessing a longer-term decline in heroin use, for reasons that may include reduced interest in the drug and reduced availability of it. Between 2017 and 2018, the number of primary heroin users in Europe who entered drug treatment for the first time decreased in 18 of the 29 countries with available data. [5]


Most fatalities from heroin overdose occur in long-term users, usually early in their third decade of life. [6, 7] Fatality rates are higher in patients who use alcohol and other drugs such as benzodiazepines and cocaine. Death is most commonly due to respiratory failure or asphyxiation. [7, 8, 9]

The US National Center for Health Statistics reported that drug overdose deaths involving heroin more than tripled from 2011 to 2016, rising from 4,571 to 15,961 (from 11% to 25% of all drug overdose deaths). Of drug overdose deaths in which at least one specific drug was mentioned, heroin ranked first from 2012 to 2015, but was overtaken by fentanyl in 2016. [10]  

In 2018,14,996 people died from a drug overdose involving heroin in the United States, a rate of 4.7 deaths per 100,000 population.  Heroin-involved overdose death rates decreased 4.1% from 2017 to 2018, but the number of heroin-involved overdose deaths was still more than 7 times higher in 2018 than in 1999. [4]

About 3-7% of patients treated for heroin overdose require hospital admission because of complications such as pneumonia, noncardiogenic pulmonary edema, and infectious complications. [6]


Although heroin addiction has traditionally been viewed as a disease of the economically disadvantaged population, addiction among the affluent is grossly underreported. According to the CDC, heroin initiation rates generally increased across most demographic subgroups from 2002-2011. During that time, however, reported rates of heroin initiation were highest among males, persons aged 18–25 years, non-Hispanic whites, those with an annual household income of less than $20,000, and those residing in the Northeast. The racial/ethnic population with the highest previous-year heroin use was non-Hispanic whites. [11]


Although heroin addiction has traditionally been viewed as a disease of males, addiction among females is grossly underreported. According to the CDC, the average number of self-reported past-year heroin users in 2017 was 600,000 males versus 286,000 females. The death rate for heroin overdose in 2017 was almost three times higher in males than in females. [12]


According to the American Association of Poison Control Centers' National Poison Data System, 4561 of the 4859 single exposures to heroin reported in 2019 were in persons 20 years of age and older; 25 were in those younger than 6 years and 93 were in teenagers. [13] According to the CDC, in 2017 the heroin overdose death rate was highest in those aged 25–34 years. [12]