Heroin

General 4: Effects on the brain

You cannot take heroin without risking serious damage to your body. Morphine, the active substance, suppresses the activity of the brain’s breathing centre. An overdose of heroin can stop your breathing altogether. That can be fatal.

Heroin also affects the brain in other ways. It stimulates the vomiting centre, constricts the pupils of the eye, suppresses coughing impulses and interferes with intestinal functions, causing constipation.