Heroin is an opioid drug made from morphine, a natural substance taken from the seed pod of the various opium poppy plants grown in Southeast and Southwest Asia, Mexico, and Colombia.

Heroin can be a white or brown powder, or a black sticky substance known as black tar heroin. Other common names for heroin include big H, horse, hell dust, and smack. People inject, sniff snort or smoke heroin.

Some people mix heroin with crack cocaine known as speedballing. Heroin enters the brain rapidly and binds to opioid receptors on cells located in many areas, especially those involved in feelings of pain and pleasure and in controlling heart rate, sleeping, and breathing. People who use heroin report feeling a “rush” (or euphoria). Other common effects include dry mouth, heavy feelings in the arms and legs, and clouded mental functioning. Long-term effects may include collapsed veins, infection of the heart lining and valves, abscesses, and lung complications. Research suggests that misuse of prescription opioid pain medicine is a risk factor for starting heroin use. A person can overdose on heroin. Naloxone is a medicine that can treat a heroin overdose when given right away, though more than one dose may be needed.

Heroin can lead to addiction, a form of substance use disorder. Withdrawal symptoms include severe muscle and bone pain, sleep problems, diarrhea and vomiting, and severe heroin cravings.

A range of treatments including medicines and behavioural therapies are effective in helping people stop heroin use. However, treatment plans should be individualized to meet the needs of the patient.