Butterbur, a popular over-the-counter nutraceutical used for the prevention of migraine, has recently been associated with serious safety concerns. Common butterbur (Petasites hybridus) is a perennial plant that contains chemotypes, termed “petasins,” that are thought to be positively pharmacologically active and may have an anti-inflammatory effect. Butterbur has long been used in herbal medicine for the treatment of many conditions, including allergic rhinitis; as an antispasmodic; and in the prevention of migraine.

Reference : by Thomas P. Bravo, MD and Bert B. Vargas, MD,https://www.neurologytimes.com/headache-and-migraine/migraine-preventative-butterbur-has-safety-concerns , july 5th,2019