Botox Approved for Chronic Migraine

The FDA has approved onabotulinumtoxinA (Botox) for prophylaxis of chronic migraine (more than 14 migraine days monthly).
Treatment involves injections into several areas of the head and neck, about every 12 weeks. Botox was already frequently used off-label for migraine.
In studies, Botox recipients had significantly fewer days with migraine, but not fewer episodes, than placebo recipients, the New York Times reports. It is unclear exactly how the drug prevents migraine. The drug is estimated to cost between $1000 and $2000, analysts tell the Times.
Botox carries a boxed warning, saying that the drug can spread beyond the treatment sites and cause symptoms of botulism, but so far, no serious adverse events have been reported with the regimen used for migraine.