Patients who met the International Headache Society criteria for a migraine, were ages 18 to 65, and had at least two to six attacks per month over the preceding 3 months, were treated with Butterbur extract at various dosages to determine the effectiveness against migraines.
Over 4 months of treatment migraine attack frequency was reduced by 48% for Petasites extract 75 mg twice a day, and 36% for Petasites extract 50 mg twice a day. 68% of patients in the Butterbur extract 75-mg twice a day group had at least a 50% reduction in migraine attacks.
The researchers concluded:
“Petasites extract 75 mg twice a day is more effective than placebo and is well tolerated as a preventive therapy for migraines. “