Drug-induced cystitis caused by herbal medicine (Bofutsushosan).

Bofutsushosan (BTS), one of many traditional Japanese medicines (Kampo medicines) is attracting attention for obesity and metabolic syndrome. We report allergic cystitis caused by 8-year BTS usage in a 70-year-old female. The patient presented with micturition pain with sterile pyuria over a 3-month period. Cystoscopy showed diffuse urothelial erythema and edema. Urine cytology specimens showed increased eosinophilic cells. By discontinuing BTS, the cystitis symptoms disappeared after 4 days, and urinalysis normalized. Resuming BTS without physician approval resulted in cystitis symptoms and after cessation the symptoms rapidly subsided. This is the first English case report linking allergic cystitis to herbal medicine.