[A case of acute eosinophilic pneumonia due to Sho-saiko-to].

A 16-year-boy who had taken a common over-the-counter cold remedy containing Sho-saiko-to, presented with fever, severe cough, sputum and dyspena. Two days later, he was admitted because a negative density, pulmonary edema-like shadow was noted on chest X-ray. A diagnosis of drug-induced pneumonia was strongly suspected, because an arterial blood gas analysis showed severe hypoxemia and leukocytosis with eosinophilia, and the chest X-ray showed a diffuse negative density pulmonary edema like shadow bilaterally. The findings on microscopic examination of transbronchial lung biopsy specimens were compatible with eosinophilic pneumonia. The eosinophil percentage in the bronchoalveolar lavage fluid was high. The result of a lymphocyte-stimulation test was positive for Sho-saiko-to, and Sho-saiko-to-induced pneumonia was strongly suspected. The patient ceased taking the cold remedy, and prednisolone was given. The clinical symptoms, severe hypoxemia, and chest X-ray findings markedly improved. To the best of our knowledge, there have been no previous reports of acute eosinophilic pneumonia induced by Sho-saiko-to.