[A case where herbal medicine sho-seiryu-to induced interstitial pneumonitis]

A 67-year-old man, treated for years for hypertension, presented with a persistent dry cough and dyspnea 10 days after the administration of drugs including Sho-seiryu-to against the common cold. Chest X-ray and CT scans revealed diffuse reticular shadows in both lung fields. Under a suspected diagnosis of drug-induced pneumonia or a complex of bacterial and interstitial pneumonia, Sho-seiryu-to was discontinued and antibiotics started. After several days, chest X-ray reticular shadows developed and hypoxia worsened. Subsequently the patient received Prednisolone. Two days later his symptoms and findings markedly improved. Drug lymphocyte stimulation tests for Sho-seiryu-to using peripheral lymphocyte were positive and other drugs were negative. Chest CT showed the reversed halo sign in right middle zone, which was relatively specific to the cryptogenic organizing pneumonia. On the basis of clinical history and these findings, we diagnosed a drug-induced interstitial pneumonia caused by the herbal medicine Sho-seiryu-to. To our knowledge, this is the first case of Sho-seiryu-to induced interstitial pneumonia to be reported.