Pneumonitis induced by ou-gon (scullcap).

A 53-year-old Japanese man with recurrent interstitial pneumonia was referred to us. The patient had taken a traditional herb medicine, otsu-ji-to, before the onset of pneumonia. A provocation test for each herbal ingredient contained in otsu-ji-to revealed that the pneumonitis had been induced by ou-gon (scullcap). Lymphocytosis with the CD8+ T-cell subset predominance was found in the bronchoalveolar lavage fluid and lymphocytic alveolitis was noted in the transbronchial lung biopsy specimen after the provocation test. Ou-gon, or scullcap, should be included in the list of drugs with definite causal association with pneumonitis.