Best known as a cosmetic therapy to banish facial frown lines, botulinum toxin type A, or Botox, was approved to prevent migraines in 2010, but only for patients who experience 15 or more migraine headaches a month.
Today, about half of the $1.6 billion annual sales of Botox are from migraine and other non-cosmetic uses, a company spokesperson tells WebMD.
In the new study, which appears this week in the Journal of the American Medical Association, researchers analyzed findings from 27 trials that compared Botox to placebo and four studies that compared it to other migraine treatments.
The analysis found that Botox injections were not effective for preventing migraines in patients who have less than 15 headaches a month. The treatment also did not appear to benefit patients with chronic tension headaches.
But Botox-treated patients with chronic migraines and daily headaches had an average of two fewer headaches per month.
Researcher Jeffrey L. Jackson, MD, of the Medical College of Wisconsin, says it is clear that much better migraine therapies are needed, especially for the most frequent sufferers.
"All of the available migraine treatments benefit some patients and not others," he tells WebMD. "Until we really understand migraines it will be hard to design treatments that work well for all patients."
He says that while the average Botox patient may not experience big improvements, results for some patients might be dramatic.
Botox Finding 'No Big Surprise'
Headache specialist Satnam Nijjar, MD, of Johns Hopkins University School of Medicine, says the research analysis will surprise few clinicians working in the field.
"This review emphasizes that most patients experience modest benefits, but we already knew that," he tells WebMD.