The MHRA is warning consumers about the risks associated with the use of unlicensed herbal products containing Butterbur (Petasites hybridus), which are being marketed in the UK.  

Butterbur products, most commonly used to treat migraine and hayfever, have been associated with cases of liver toxicity (40 cases so far reported in the literature, including two cases of acute hepatitis that resulted in liver failure and transplantation).  There are no products containing Butterbur licensed for use in the UK under the Traditional Herbal Registration scheme, and the sale of butterbur is prohibited or restricted in a number of other European countries.  Please see the link below for further information.