In two controlled clinical trials a total of 170 migraine patients were exposed to doses of a special butterbur extract between 100 and 150 mg daily for at least three months. Compared to placebo, no significant differences were observed regarding adverse events rated to be at least possibly causally related to the product, except for "eructations." This well-known adverse effect is of mild and transient nature and occurred in about 20% of study patients." A total of 246 patients (203 suffering from migraine; including 108 children and adolescents from 6-17years of age) were treated with the special butterbur extract at various doses for several months in the framework of four post-marketing surveillance studies, three of which have been finished and two of them have been published already. Adverse events reported to be possibly or probably causally related to the product were seven cases of "eructations," one case of""bad smell and taste of the product" and one case of a "skin rash." Excellent tolerability at doses from 50 to 150 mg was reported for children from 6 years of age. Documentation of spontaneous reports started in 1976. A total of 75 reports of suspected adverse reactions from Germany and 18 spontaneous reports from other countries were received by the manufacturer until June 30, 2002,therefore representing an overall frequency of suspected adverse reactions of as low as 0.022%. Only 19 reports were determined to be possibly and 8 reports to be probably causally related to the administration of the special butterbur root extract.