[Case of pneumonitis caused by Yokukansan]

A 74-year-old man was admitted to our hospital complaining of severe neck pain and general fatigue. He had been undergoing treatment for post-operative neck pain at the out-patient clinic of our hospital, but was now complaining of pain more intense than usual. Chest X-rays revealed diffuse ground glass shadows in bilateral lung fields, and computed tomography revealed diffuse intestinal shadows. A drug lymphocyte stimulation test (DLST) was also performed at that time. Steroid pulse therapy improved the clinical symptoms, hypoxemia and chest X-ray findings. DLST performed again with Yokukansan and Hachimijiogan 133 days after the initial diagnosis of pneumonitis showed Yokukansan was positive. This result showed Yukukansan may be a causative drug for allergic drug-induced pneumonitis. Any drugs including kanpo may be possible to induce allergic pneumonitis.