What is Heroin?

Heroin is a highly addictive opioid drug that is synthesized from morphine. 

in 2011, 4.2 million Americans age 12 or older had used heroin at least once in their lives. It is estimated that about 23% of individuals who use Heroin become dependent on it.

Prescription opioid pain medications such as Oxycontin and Vicodin can have effects similar to heroin when taken in doses or in ways other than prescribed, and they are currently among the most commonly misused drugs in the United States. Research now suggests that misuse of these drugs may be leading to heroin misuse.

How is Heroin used?

Heroin can be injected, inhaled by snorting or sniffing, or smoked. All three routes of administration deliver the drug to the brain very rapidly, which contributes to its health risks and to its high risk for dependence. 

Heroin Affect the Brain?

When it enters the brain, heroin is converted back into morphine, which binds to molecules on cells 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, which controls automatic processes critical for life, such as blood pressure, arousal, and respiration.

Heroin overdoses frequently involve a suppression of breathing. This can affect the amount of oxygen that reaches the brain, a condition called hypoxia. Hypoxia can have short- and long-term psychological and neurological effects, including coma and permanent brain damage.

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.

Researchers are also investigating the long-term effects of opioid addiction on the brain. One result is tolerance, in which more of the drug is needed to achieve the same intensity of effect. Another result is dependence, characterized by the need to continue use of the drug to avoid withdrawal symptoms. Studies have shown some deterioration of the brain’s white matter due to heroin use, which may affect decision-making abilities, the ability to regulate behavior, and responses to stressful situations.

Injection Drug Use and HIV and HCV Infection

People who inject drugs are at high risk of contracting HIV and hepatitis C (HCV). This is because these diseases are transmitted through contact with blood or other bodily fluids, which can occur when sharing needles or other injection drug use equipment. (HCV is the most common blood-borne infection in the Unites States.) HIV (and less often HCV) can also be contracted during unprotected sex, which drug use makes more likely.

Because of the strong link between drug misuse and the spread of infectious disease, drug misuse treatment can be an effective way to prevent the latter. People in drug misuse treatment, which often includes risk reduction counseling, stop or reduce their drug use and related risk behaviors, including risky injection practices and unsafe sex. 

"DrugFacts: Heroin." NIH National Institute on Drug Abuse