Heroin is a painkilling drug made from morphine which is derived from the opium poppy. It comes as a white powder when pure. Street heroin is usually brownish-white. It is snorted, smoked or injected.

In small doses, heroin gives the user a sense of warmth and well-being. Higher doses can make them drowsy and relaxed. Excessive amounts can result in overdose, coma, and in some cases death. First-time use often leads to side-effects like dizziness and vomiting.

Heroin is very addictive. Getting the next fix can dominate a user's life. Tolerance develops, which means the user needs more heroin to get the same effect. Users who form a habit may end up taking the drug just to feel normal.

Those who start by smoking or snorting heroin sometimes switch to injection to maximise the high. Injecting can damage veins and lead to gangrene. Withdrawing from heroin can be very hard. Many people manage to kick the drug, but mentally it may take years to be free.