Heroin starts life as the dried milk of the opium poppy, which is then made into a drug called morphine. Doctors use morphine as a pain killer, but it is not difficult to make heroin from it, which is more than twice as strong. It usually comes as a white or lightish brown powder, and is cut (mixed) with other substances like sugar and paracetamol when selling it. Heroin users sometimes sniff or smoke it, more often they inject into their veins. This makes the effects much stronger, but much, much more dangerous because of the danger of injecting all sorts of really awful things straight into their blood stream. Also if dirty needles are used there is a risk of injecting the hepatitis and AIDS viruses. Heroin is a sedative which means it depresses the nervous system and means you can't feel pain in your body or your emotions (until it wears off). It gives users a feeling of warmth and well being. In the 1700s and 1800s China had a big problem with opium addicts. Amazingly, the opium was deliberately imported into China by the British East India Company both to make money and to 'subdue' the population.