In a randomized controlled trial in 245 adults with 2–6 migraine headaches per month, the intention-to-treat (ITT) analysis showed that the participants who took 75 mg of butterbur extract twice a day had a greater decrease in migraine frequency compared to the participants who took a placebo (–45% vs. –28%). However, taking a smaller dose (50 mg of butterbur extract twice a day) was not significantly better than a placebo.[1]
The Canadian Headache Society strongly supports the use of butterbur extract for migraine prevention but warns that only properly tested products should be used. Unprocessed butterbur extract can contain pyrrolizidine alkaloids (PA), which are known to cause liver damage. It’s important to check that butterbur products are PA-free prior to use.[2] However, not all expert organizations agree with this recommendation. The American Headache Society and the American Academy of Neurology retracted their strong recommendations of butterbur due to concerns of liver toxicity. Furthermore, in both the United Kingdom and Germany, the use of butterbur is no longer authorized due to safety concerns.[3]