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What Does Heroin Do to the Body and Brain?



Medically Reviewed by Dr. Mohammed Saeed, MD.

Heroin is an opioid drug that can have severe, sometimes irreversible, effects on the body and brain. The brain controls all life-sustaining functions of the body. Because heroin changes the structure and physiology of the brain, all functions are adversely impacted by its use.

The chemical makeup of heroin mimics the body’s naturally occurring endorphins, which serve to block pain signals and produce a sense of well-being. Heroin users achieve these same feelings of euphoria, pain relief, and lessened anxiety, at a more intense level than delivered by the body’s natural endorphins.

Immediate effects of heroin use

Heroin takes effect almost immediately, and is highly addictive, both physically and psychologically. Once the drug enters the brain, the immediate surge of pleasure may be accompanied by dry mouth, nausea, intense itching, and a heavy sensation in the body. Next drowsiness occurs, along with impaired mental functioning. As heroin binds to receptors in the brain, it may permanently damage the brain’s ability to naturally produce the endorphins that balance mood and pleasure. Life-threatening physical responses may include a slowing of the heart rate, blood pressure, and breathing functions, which can lead to coma, brain damage, or death.

Long-term effects of heroin use

Habitual use of heroin results in serious imbalances and impairment of body systems controlled by the brain. Permanent damage may be caused to the:

  • Central nervous system (brain and spinal cord), which controls most functions of the body
  • Brain stem, which controls sleep, breathing, and heart rate
  • Limbic system, the reward center of the brain, which controls emotions, and the ability to feel happy
  • Cerebral cortex, which governs thinking, problem solving, decision making, and the ability to process information

In addition to dangerous effects on heart rate, blood pressure, and breathing, other physical effects may include:

  • Heart valve abscess
  • Diseases such as tuberculosis and pneumonia
  • Liver disease
  • Kidney disease
  • Chronic constipation
  • Chronic insomnia
  • Sexual dysfunction in men
  • Irregular menstrual cycle in women

Added risks for those who inject heroin include skin infections, collapsed veins, and blood-borne diseases like HIV/AIDS, Hepatitis B, and Hepatitis C.

Long-term heroin use is linked to the deterioration of white matter in the brain. Studies associate this deterioration with diminished capacity to make decisions, self-regulate, and respond appropriately to stress. Severe depression can result, with the potential for suicide.


Dr. Mohammed Saeed, MD.

Dr. Saeed is a psychiatry specialist with over 40 years of experience in the medical field. He received training in General Psychiatry at the University of Texas Medical Branch, where he was selected as the Medical Director of the Division of Child and Adolescent Psychiatry. He currently serves as the medical director at Into Action Recovery Centers. Full Bio

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