The Food and Drug Administration has approved using Botox for adults who experience 15 or more days of migraines each month.
Doctors will inject patients in the neck or head every 12 weeks to dull future headaches.
Experts say Botox has not been shown to work for less frequent migraines or other types of headaches.
Allergan, the company that makes Botox, estimates that 3.2 million Americans suffer from chronic migraines.
