Just like a drug

Some things are more addictive than others

Drugs top the bill of addictive substances. Efforts to rank them generally take into account the good feelings – or intoxication – from taking a drug, whether users develop tolerance to its effects, how bad withdrawal symptoms can be, and how hard it is to stay off if you stop.

With all these things in mind, heroin is generally considered more harmful (and more addictive) than cocaine – and crack cocaine more so than cocaine alone. Tobacco, ketamine and marijuana (cannabis) come lower down the list. Surprisingly, one study suggests that alcohol is more harmful than any illegal drug, results which may have been skewed by using ‘harm to others’ as an inclusive criterion for overall harmfulness. Even so, in 2013 there were 2,955 registered drug-related deaths and 8,416 registered alcohol-related deaths in the UK.

UK researchers assessed the harmfulness of 20 substances. How does harm relate to legal classification?
Credit: Graph adapted (with permission from the author) from Nutt et al. Lancet 2010;376(9752):1558-65.

Other drugs are not physically addictive. Ecstasy (MDMA), for instance, does not lead to the uncontrollable craving seen with some other drugs. In fact, repeated use of MDMA seems to go along with reduction in the amount of the neurotransmitter serotonin in the brain, which may limit some of MDMA’s pleasurable effects.

A new group of drugs – novel psychoactive substances, or ‘legal highs’ – have gained increasing popularity in recent years, yet can often be stronger and potentially more addictive than illegal drugs. These substances have similar effects to illegal drugs, and are often synthetic forms of cannabis (chemicals that act on cannabis receptors) mixed with other chemicals. While they cannot legally be sold for human consumption, they are often sold as plant food. A specific novel drug may become subject to a temporary class drug order (TCDO) for a year, while being reviewed to potentially gain a classification, during which time it is illegal to make and supply the drug.


About this resource

This resource was first published in ‘Addiction’ in June 2010 and reviewed and updated in September 2015.

Education levels:
14–16, 16–19, Continuing professional development