To the Editor: A potentially important, if somewhat crude, means of suicide prevention involves restricting the availability of commonly used methods. In 1967, for example, restrictions on barbiturate prescribing in Australia led to declines in its use for suicide and in overall suicides.1 A crucial concern with this approach is that distressed individuals might use alternative, more lethal, methods. In Britain, there is just such a concern in relation to recent legislation restricting the availability of paracetamol.2

Analysis of the natural experiment investigated by Balit and colleagues3 does not, however, provide useful insights into the impact of paracetamol sales restrictions. Their most consistent finding was that, despite restricted availability for the period studied, paracetamol accounted for about 10% of all contacts with the two poisons information centres in both time periods.

In Britain, in 1998, paracetamol purchases from chemists and supermarkets were restricted rather than banned.4 Up to 16 g (32 tablets) may be purchased from pharmacies and 8 g from supermarkets. The aim was not to prevent overdose but to reduce its severity. Presumably, over the periods studied by Balit et al, paracetamol was simply unavailable. As their analysis is based on calls to poisons information centres rather than on the clinical records of people presenting to hospital, they could not assess whether changes in paracetamol availability influenced indicators of severe poisoning — death and liver damage. A decline in the number of severe paracetamol poisonings, without a change in total episodes of paracetamol overdose, might be considered the most important end-point.

Attention is drawn to statistically significant rises in calls concerning ibuprofen in one centre and aspirin in the other. The clinical significance of these observations is questionable. Overdoses of ibuprofen are less harmful than paracetamol,5 and the significant rise in aspirin overdose represents an increase from two calls per year to five per year — an increase of only three calls. Of note is the fact that the largest absolute decline in calls related to paracetamol (from 423 per year in 1997–1999 to 370 per year in 2000). Furthermore, as only two time points are compared, it is impossible to determine whether the increases reflect year-on-year changes in use of particular drugs for overdose, as might occur with increased ibuprofen sales.

Legislation seeking to influence patterns of harm through changing the availability of drugs which are beneficial when used safely should be monitored carefully.4 Balit et al do not provide convincing evidence concerning the effects of paracetamol sales restrictions on population health.