A 54-year-old man started to take oren-gedoku-to (coptis detoxifying decoction) because he was experiencing chronic hot flashes, night sweats and insomnia. He developed a high fever from the day of intake. At day 17, he stopped taking oren-gedoku-to because of malaise and chills, and he was admitted to our hospital. Drug-induced pneumonitis was suspected, and all drugs were stopped. Consequently, his symptoms, laboratory data and chest X-ray findings markedly improved. The results of a lymphocyte stimulation test were positive for oren-gedoku-to and one of its components, ougon (Baikal skullcap). Based on these findings, we diagnosed him with pneumonitis caused by ougon.