Japanese traditional (Kampo) medicine saved many lives during the Spanish influenza pandemic of 1918-­20. In Japan, acute viral respiratory infections represented by influenza have been called shokan (cold damage), and so on since ancient times. These infections were treated by prescriptions that were adopted from Chinese classical texts including “Shanghan lun (Treatise on Cold Damage Diseases),” “Xiaopin fāng (Prescriptions of Sketch),” “Tai ping hui min he jì ju fang (Formulary of the Bureau of Taiping People's Welfare Pharmacy),” and “Wan bing hui chun (Restoration of Health from Myriad Diseases).” Additional materials include (but are not limited to) “Ishimpo (Prescriptions of Medical Sprit),” “Ton-­i-­sho (Abstract of Medical Enlightenment),” and the diaries of some Muromachi aristocrats. In the Edo period (1603-1868), treatment with Kampo medi­cines developed uniquely in Japan, but due to medical and economic disparities, many patients could not be treated by Kampo experts. Ephedra herb, a key drug for treating shokan (cold damage), has shown major problems in terms of quality, because it has been confused with plants of the genus horsetail since at least the 8 th century ; its medicinal effects may therefore have been underestimated. The effectiveness of Kampo medicine against the novel influenza/coronavirus pandemic is anticipated, however, in order to fully exploit its potential, it is important that physicians with sufficient knowledge of Kampo should use Kampo medications properly.