3. Cocaine

Once a drug exclusively for the rich and famous, but now the most popular class A drug in Britain, with more than 1.2 million people taking it in the UK in 2009. For some cocaine is the ideal addition to a night out, but for others taking it became a life-changing event, including the young man that needed a pacemaker fitted at just 17 after cocaine gave him a heart attack and a patient undergoing surgery to repair a nose torn apart by too many lines of coke.