The efficacy of goshuyuto, a typical Kampo (Japanese herbal medicine) formula, in preventing episodes of headache

Objective: The purpose of this clinical trial was to assess the efficacy of goshuyuto, a typical Kampo formula, in preventing episodes of headache in chronic headache patients. Research design and methods: Because the treatment target of a Kampo formula is decided on a basis different to that of Western medicine, we first selected patients belonging to a subgroup that responded to goshuyuto before conducting the usual randomized controlled trial. During stage 1, the subjects were instructed to orally consume goshuyuto for 4 weeks. Only those subjects judged as responders advanced to stage 2, during which a double-blind, randomized, placebo-controlled study was conducted. The subjects consumed the same dose of goshuyuto or placebo for 12 weeks. Results: Of the 91 subjects enrolled in stage 1, 60 were judged as responders. Of these, 53 advanced to stage 2; 28 were assigned to the goshuyuto group and 25 to the placebo group. The decrease in the number of days on which headache episodes occurred was greater in the goshuyuto group than in the placebo group (2.6 +/- 3.7 vs. 0.3 +/- 4.0 days, p = 0.034); no difference was observed with regard to the reduction in the frequency of consuming reliever medications (2.2 +/- 4.0 vs. 1.4 +/- 8.2, p = 0.672). Improvement in the associated symptoms was observed in more than 50% of the subjects in the goshuyuto group. Conclusion: Goshuyuto is useful in preventing episodes of headache in chronic headache patients. Responder-limited design is a candidate for evaluating Kampo medicine.