Botox injections show ‘small to modest' benefits in preventing migraine and headache, say US researchers.
The meta-analysis included 315 randomised controlled trials that evaluated the effect of botulinum toxin A injections on the reduction in frequency or severity of headaches.
Compared with placebo, botox injections were associated with a reduction of 2.06 headaches per month for patients with chronic daily headaches and 2.30 per month for those with chronic migraine. No differences were seen with episodic migraine or chronic tension-type headaches.
Compared with topiramate and amitriptyline for prophylaxis against chronic migraine headaches, botox injections were not associated with a significant reduction in headache frequency. Topiramate was effective in reducing 1.4 headaches per month, while amitriptyline reduced frequency by 2.1 per month.
When compared with valproate in patients with chronic and episodic migraines, there was no association in reduction of headache frequency with botox injections.
Study lead Dr Jeffrey Jackson, of the Medical College of Wisconsin in Milwaukee, said botox injections had only a ‘small to modest' effect' compared with placebo.
He said: ‘The beneficial association of botulinum toxin A in prophylaxis of headaches appears limited to patients with chronic migraine headaches and the absolute reduction in the number of headaches per month is only two to three days a month.'
JAMA 2012; 307: 1736-1745