The UK Science and Technology Select Committee, which advises the government, commissioned an assessment of 20 legal and illegal stimulants to examine the actual social and physical harm they cause based on scientific evidence.

Controlled drugs are currently categorised to reflect the penalties they incur for possession and dealing. The highest category, class A, carries the largest legal penalties and includes heroin, cocaine, ecstasy and magic mushrooms. Class B includes speed and barbiturates, while cannabis and some tranquillisers are in class C.

However, the new league table puts alcohol in the top five most harmful drugs, alongside heroin, cocaine, barbiturates and street methadone. Ecstasy and LSD, currently categorised as class A drugs, come well below both tobacco and alcohol.

The UK drug classification system needs to be overhauled to reflect the harm these substances cause, says the committee. “The government, its advisors and the police are in confusion about the relationship between drug classification and criminal penalties for possession,” says committee member Evan Harris, a Liberal Democrat MP. “We’ve made our recommendations to the government and we’re very hopeful that they will act.”