The review discusses the adverse effects of Kampo medicines, focusing on interstitial pneumonia and other immunoallergic reactions. It mentions a rapid decline in the market for Kampo medicines after 10 deaths were attributed to interstitial pneumonia as a side effect of shosaikoto. Various studies and reports have described cases of pneumonia and other adverse reactions caused by Kampo formulas, specifically mentioning interstitial pneumonia as a potential side effect in the drug package inserts. A case of hepatitis and interstitial pneumonia apparently caused by two specific Kampo medicines is discussed. The text also mentions a study reporting 3.1% of Kampo-medicine-induced interstitial pneumonia cases, as well as other studies on the association between Kampo medicine and interstitial pneumonia and liver dysfunction. Interestingly, interstitial pneumonia as an adverse effect has only been observed in Japan, with no known cases from other countries or natural remedies. One Kampo medicine, Daisaikoto, may also cause interstitial pneumonia or hepatitis as serious side effects.