When used recreationally heroin is most commonly injected, but it can also be smoked or snorted. When injected, it produces a surge of euphoria within 7 to 8 seconds, and within 10 – 15 minutes if smoked or snorted. When used recurrently it rapidly becomes addictive.

Heroin addiction arises when recurrent use induces molecular and neurochemical changes in the brain. Tolerance of the drug increases dramatically, resulting in compulsive behavioural changes -addicts desperately seek more and more of the drug. With alarming rapidity, a person’s over-riding priority in life becomes obtaining the drug, a frantic quest that often draws users into crime to feed their habit.

Although abruptly stopping heroin is possible, it is advisable to seek heroin addiction treatment where possible, as the effects of sudden withdrawal are exceptionally painful and disturbing. Known as “cold turkey”, the symptoms include muscle cramps and aching bones, shivering and cold flashes, insomnia and restlessness, as well as diarrhoea and vomiting. These reach a crescendo between 24 and 48 hours after the last dose, but usually subside after a week, although some people have been known to continue showing milder symptoms of withdrawal for several months. Craving for heroin, however, can persist for many weeks and even months after the withdrawal effects have disappeared.

Heroin addiction treatment works better when heroin addiction is not of long-standing. Frequently combinations of pharmacological and behavioural therapies are used. A heroin substitute such as methadone may help block the craving and moderate the withdrawal but is itself highly addictive. Newer, less addictive medicines such as buprenorphine are increasingly being used; these substitutes are only available through medically authorised prescription.