All opiates are derived from opium, a naturally occurring juice extracted from the seed pod of certain varieties of poppy (Papaver somniferum and Papaver setigerum). Heroin or 'diacetylmorphine' is a semi-synthetic derivative of morphine.

Heroin is increasingly used in dance clubs as a chill-out drug and has also recently become popular on the gay scene. It's relatively cheap and many smoke it to ease comedown from Ecstasy, speed or coke.

The price of heroin varies according to how much is available. Generally it's between $59-$88 per gram, or around $22 for a third of a gram.