Despite media reports that suggest botox could be an effective way to prevent migraines, a new study reveals botox injections are no more effective than placebo.

The Headache paper reported the results of an exploratory 11-month randomised, double-blind, placebo-controlled study. Some 369 subjects entered a single-blind, placebo run-in period for 30 days and divided into placebo and non-placebo responders. They were then randomised to receive three botox treatments or placebo at 90-day intervals.

Patients in both the botox and placebo groups experienced an average of 2.4 and 2.2 migraine episodes per month, with at least 50% of all patients in each group experiencing fewer migraines per 30 day period. Among those with between 12-15 headache days per month, those in the botox group had four fewer headache episodes at the end of the study, compared with less than two fewer headaches in the placebo group. This difference was not significant, however.

The authors note that while there was no difference in treatments, there were several factors affecting the trial, including a strong placebo response and the fact subjects were allowed to use symptom-relieving and preventative medication throughout the trial.

A second study in Europe, found similar results, with improvements seen in both the placebo and botox groups, but not significant difference between groups.

_{Aurora SK; Gawel M, Brandes JL et al for the Botox North American Episodic Migraine Study Group. Botulinum Toxin Type A Prophylactic Treatment of Episodic Migraine: A Randomized, Double-Blind, Placebo-Controlled Exploratory Study. Headache 2007;47:486-499.}

_{Relja M, Poole AC, Schoenen J et al for the European BoNTA Headache Study Group. A multicentre, double-blind, randomized, placebo-controlled,parallel group study of multiple treatments of botulinum toxin type A (BoNTA) for the prophylaxis of episodic migraine headaches. Cephalalgia 2007. doi:10.1111/j.1468-2982.2007.01315.x}

What the WHA thinks

• It's still not been proven that botox can make a difference in preventing migraines.
• These studies found there was no difference between placebo or botox, although the results looked more promising for those who experience headaches for at least 12 days per month (but less than 15 days, i.e. they do not have chronic daily headache).
• The authors suggest that higher doses may be more effective but further study is needed.