Ms. A, a 50-year-old woman, was referred to our hospital for chronic depression or dysthymic disorder with alcohol dependence. There was no history of drug allergy. She was given 100 mg of thioridazine orally once a day and 10 mg of diazepam four times a day. After 2 days, she noticed an erythematous eruption on her ankles. Thioridazine treatment was first discontinued. As the eruption became more erythematous and affected both extremities and flanks within a few hours, methylprednisolone was administered at a dose of 80 mg daily. The next day, the eruption progressively became bullous, and Ms. A’s condition worsened. She felt ill and had pyrexia at 39.4˚C. Urea and creatinine levels stayed within normal limits. The results of blood cultures were negative. A skin biopsy revealed bullous vasculitis with numerous eosinophils within the dermis. Diazepam therapy was then discontinued, which led to the resolution of pyrexia and the progressive healing of the cutaneous lesions. Postinflammatory ulcers persisted on both ankles for 2 months. The results of a lymphocyte blast transformation test was positive for diazepam.