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.
He says most of his Botox patients have tried several drugs to prevent migraines and lessen their severity, and they either did not benefit or could not take the side effects.
Anti-seizure drugs, such as topiramate (Topamax, Topiragen) and gabapentin (Fanatrex, Gabarone, Gralise, Horizant, Neurontin), are widely prescribed for migraine prevention, but these drugs can have side effects such as fatigue, dizziness, and nausea.
But he says patients who don't like needles may find drugs preferable to Botox, which involves 25 to 30 small injections in the head region every three months or so.
Neurologist Robert Duarte, MD, tells WebMD that many of his patients who are helped by Botox are not bothered by the injections.
Duarte directs the Pain Center at the Cushing Neuroscience Institute at the North Shore-LIJ Heath System in Manhasset, N.Y.
"A significant number of patients that I treat experience fewer headaches and less intense headaches on this treatment," he says. "Many still require drug treatments, but they are feeling a lot better."
Botox Maker Responds
In an interview with WebMD, a spokesperson for Botox manufacturer Allergan Inc. says the study reinforces its role as a treatment to prevent chronic migraines.
Crystal Muilenburg, Allergan's director of corporate communications, says some patients in company-sponsored trials experienced a 50% reduction or more in headache days per month after two cycles of Botox, and more than 2 out of 3 patients showed some improvement.