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Heroin is the common name for the psychoactive drug, diacetylmorphinei. It can be smoked, sniffed, inserted rectally or injected. Heroin is processed from morphine, which is a naturally occurring substance extracted from opium poppy plants. The opium poppy has been cultivated for more than five thousand years for a wide variety of medicinal uses, most notably as an analgesic used in the treatment of pain.  


Heroin was first synthesized from morphine in 1874. From 1898 through 1910, the German pharmaceutical company, Bayer, marketed it under the trademark name ‘Heroin’ as a cough suppressant and as a “non-addictive” morphine substitute. It grew in popularity until the U.S. government restricted its use through the Harrison Narcotics Act in 1914 and made it illegal in 1924 through the Heroin Act.  

Heroin is currently classified as a Schedule I substance, which means that the federal government has determined that it has no currently accepted medical use and has a high potential for abuse. 

People who use heroin describe a feeling of warmth, relaxation and detachment, with a lessening sense of anxiety. It is a powerful sedative, and due to its analgesic qualities, physical and emotional aches and pains can also be diminished. These effects appear quickly and can last for several hours, depending on the dosage and the mode of administration. 

When it is injected or smoked, it is quickly introduced into the bloodstream and leads to an instant rush of euphoric pleasure. In addition to pain relief and sedation, heroin use can also lead to constipation, nausea and respiratory depression, which causes shallow breathing, lowered blood pressure and reduced heart rate. Prolonged use can lead to physical dependence. Some people who use heroin do so because this physical dependence means that if they stop using heroin, they will experience severe withdrawal symptoms that will make them physically sick. Many others continue using heroin because it provides a feeling of comfort and safety.

Heroin differences to other opioids

• Morphine is a naturally occurring substance derived from the opium poppy plant often used to alleviate pain and other physical ailments. It was the first opiate to be synthesized and thus, its use predates the use of heroin or oxycodone. The U.S. classifies it in Schedule II, which means the federal government has determined that it has potential for misuse and dependence, but also has accepted medical use and can be prescribed to patients.

• Heroin is processed from morphine. It is classified as a Schedule I substance, which means the federal government has determined that it has no currently accepted medical use. However, heroin (diacetylmorphine) is available medically in some limited circumstances, particularly in Europe and Canada. In the U.S., almost all heroin comes from the unregulated market.

• Oxycodone and Hydrocodone are semisynthetic opioids derived from the opium poppy plant, are chemically similar to morphine and are used to treat acute and chronic pain. Unlike illicitly produced heroin, their production is regulated, which means they have consistent effects and can be made available in specified doses. Semisynthetic opioids are most commonly available in pill form. OxyContin is a controlled release form of oxycodone so it is released gradually over a period of time. Oxycodone and hydrocodone are Schedule II substances, which means that the federal government has determined that it has accepted medical use.

• Fentanyl is one of the most powerful opiate-based painkillers, used to treat chronic pain patients who have developed a resistance to other less powerful opiates such as morphine or oxycodone. Its effects are active at much lower doses than other opiates and so, while the effects of fentanyl might be similar to longer lasting opiates such as heroin, morphine and oxycodone, its non-medical use is riskier due to its increased potency. Like morphine, fentanyl is a Schedule II substance. In recent years, much of the U.S. heroin supply has been mixed with synthetically created illegal fentanyl, leading to skyrocketing overdose death rates. Illegal fentanyl is not regulated and is often mixed into heroin, with or without the user’s knowledge, which has led to increased overdose deaths since 2013.

• Methadone and Buprenorphine are opioids that have been approved by the U.S. Food and Drug Administration (FDA) as medications to treat opioid dependence. They act on same receptors in the brain as other opioids

How is it taken?

Heroin can be injected, snorted/sniffed, or smoked—routes of administration that rapidly deliver the drug to the brain. Injecting is the use of a needle to administer the drug directly into the bloodstream. Snorting is the process of inhaling heroin powder through the nose, where it is absorbed into the bloodstream through the nasal tissues. Smoking involves inhaling heroin smoke into the lungs. All three methods of administering heroin can lead to addiction and other severe health problems.

How Does Heroin Affect the Brain?

Heroin enters the brain, where it is converted to morphine and binds to receptors known as opioid receptors. These receptors are located in many areas of the brain (and in the body), especially those involved in the perception of pain and in reward. Opioid receptors are also located in the brain stem—important for automatic processes critical for life, such as breathing (respiration), blood pressure, and arousal. Heroin overdoses frequently involve a suppression of respiration.


After an intravenous injection of heroin, users report feeling a surge of euphoria (“rush”) accompanied by dry mouth, a warm flushing of the skin, heaviness of the extremities, and clouded mental functioning. Following this initial euphoria, the user goes “on the nod,” an alternately wakeful and drowsy state. Users who do not inject the drug may not experience the initial rush, but other effects are the same.

With regular heroin use, tolerance develops, in which the user’s physiological (and psychological) response to the drug decreases, and more heroin is needed to achieve the same intensity of effect. Heroin users are at high risk for addiction—it is estimated that about 23 percent of individuals who use heroin become dependent on it.

What Other Adverse Effects Does Heroin Have on Health?

Heroin abuse is associated with serious health conditions, including fatal overdose, spontaneous abortion, and—particularly in users who inject the drug—infectious diseases, including HIV/AIDS and hepatitis. Chronic users may develop collapsed veins, infection of the heart lining and valves, abscesses, and liver or kidney disease. Pulmonary complications, including various types of pneumonia, may result from the poor health of the abuser as well as from heroin’s depressing effects on respiration. In addition to the effects of the drug itself, street heroin often contains toxic contaminants or additives that can clog blood vessels leading to the lungs, liver, kidneys, or brain, causing permanent damage to vital organs.

Chronic use of heroin leads to physical dependence, a state in which the body has adapted to the presence of the drug. If a dependent user reduces or stops use of the drug abruptly, he or she may experience severe symptoms of withdrawal. These symptoms—which can begin as early as a few hours after the last drug administration—can include restlessness, muscle and bone pain, insomnia, diarrhea and vomiting, cold flashes with goose bumps (“cold turkey”), and kicking movements (“kicking the habit”).

Users also experience severe craving for the drug during withdrawal, which can precipitate continued abuse and/or relapse. Major withdrawal symptoms peak between 48 and 72 hours after the last dose of the drug and typically subside after about 1 week. Some individuals, however, may show persistent withdrawal symptoms for months.

Although heroin withdrawal is considered less dangerous than alcohol or barbiturate withdrawal, sudden withdrawal by heavily dependent users who are in poor health is occasionally fatal. In addition, heroin craving can persist years after drug cessation, particularly upon exposure to triggers such as stress or people, places, and things associated with drug use.

Heroin abuse during pregnancy, together with related factors like poor nutrition and inadequate prenatal care, has been associated with adverse consequences including low birth weight, an important risk factor for later developmental delay. If the mother is regularly abusing the drug, the infant may be born physically dependent on heroin and could suffer from serious medical complications requiring hospitalization.

What are the signs and symptoms of heroin withdrawal? 

Signs and symptoms of heroin withdrawal can include depression, stomach cramps, nausea, fever, sweating, vomiting and diarrhea. It is a severe flu-like illness and the severity of the symptoms typically peaks at around 2-3 days. If untreated, some of these symptoms, such as persistent vomiting and diarrhea, can lead to dehydration, elevated blood sodium level and heart failure.

However, all of the symptoms can be treated with appropriate medical attention. These symptoms can be avoided by taking a form of opioid agonist therapy such as methadone or buprenorphine.

What Treatment Options Exist?

A range of treatments exist for heroin addiction, including medications and behavioral therapies. Science has taught us that when medication treatment is combined with other supportive services, patients are often able to stop using heroin (or other opiates) and return to stable and productive lives.

Treatment usually begins with medically assisted detoxification to help patients withdraw from the drug safely. Medications such as clonidine and buprenorphine can be used to help minimize symptoms of withdrawal. However, detoxification alone is not treatment and has not been shown to be effective in preventing relapse—it is merely the first step.


  • Heroin: NIDA Info facts; 2010.
  • 10 Facts about Heroin: Drug Policy Alliance March; 2018
  • Heroin Fast facts: National Drug Intelligence Center a component of the U.S. Department of Justice; NDIC Product No. 2003-L0559-003
  • The heroin epidemic of the 1980s and 1990s and its effect on crime trends – then and now: Technical Report: Nick Morgan; July 2014
  • Occasional and controlled heroin use. Not a problem?; Hamish Warburton, Paul J. Turnbull and Mike Hough; 2005
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