Evidence based policy? Why banning mephedrone may not have reduced harms to users

A guest post by Dr Les King.

The control of mephedrone and related compounds under the Misuse of Drugs Act in April 2010 was largely prompted by the media attention given to numerous alleged mephedrone fatalities. Subsequent toxicology examinations showed that most of those deaths were not caused by mephedrone, a finding now underscored by the latest statistics (REF 1) from the Office for National Statistics (ONS). In 2010, in England and Wales, there were just 6 deaths where mephedrone was mentioned on the death certificate. By comparison, there were 144 fatalities where cocaine was mentioned. The significance of this comparison can be understood when it is recognised that cocaine is a drug which was often substituted by mephedrone. The number of deaths alone does not tell us much about the intrinsic toxicity of a substance. However, the ratio of the number of deaths to suitable proxy measures of prevalence does provide a useful index (REF 2). The British Crime Survey (Drug Misuse Declared) (REF 3) provides one such denominator. For 2010/2011, it was reported that in England and Wales, 4.4% of 16 to 24 year olds used mephedrone in the last year. This was the same as the number using cocaine, a figure only increased to 4.7% if crack cocaine is also included. If we choose instead to look at last year use by 16 to 59 year olds, the respective proportions were: mephedrone = 1.4% and cocaine = 2.1%. Caution may be needed in interpreting the small number of mephedrone deaths in 2010, and it is possible that some cases were missed because not all toxicology laboratories were able to identify this new substance. The mortality statistics also suffer from other confounding issues, as discussed by Bird (REF 4), but it would seem that regardless of which age group we consider, and bearing in mind the uncertainties, the fatal toxicity of mephedrone is low by any standard, and may be less than 10% of that of cocaine. This confirms the concerns raised by Bird (REF 5); an unintended consequence of banning mephedrone would be a lost opportunity to save the lives of many who would succumb to cocaine poisoning.


1. Deaths related to drug poisoning in England and Wales, 2010. Office for National Statistics, 23 August 2011
2. L.A.King and J.M.Corkery, 2010, An index of fatal toxicity for drugs of misuse, Hum. Psychopharmacol. Clin. Exptl., 25, 162-166
3. Drug Misuse Declared: Findings from the 2010/11 British Crime Survey, England and Wales, Home Office, 28 July 2011
4. S.Bird, 2011, Drugs deaths in England and Wales - a wake-up call to the Registrar General, http://www.straightstatistics.org/article/drugs-deaths-england-and-wales-wake-call-registrar-general
5. S.Bird, 2010, Banned drug may have saved lives, not cost them, http://www.straightstatistics.org/article/banned-drug-may-have-saved-lives-not-cost-them