Fever and hyperthermia are the main symptoms of COVID-19 and heatstroke, it is difficult to distinguish them. We came to think that there is a need to discuss safe prevention and medical treatment for heatstroke. In view of the above issues, the Japanese Association for Acute Medicine "Committee on Heatstroke and Hypothermia" established a "Working group on heatstroke medical care given the COVID-19 epidemic" jointly with the Japanese Society for Emergency Medicine that focuses on emergency medical personnel including paramedics and nurses, the Japanese Association for Infectious Diseases, an academic society of infectious disease, and the Japanese Respiratory Society, an academic organization on respiratory diseases. The precautions for prevention of heatstroke this summer during the coronavirus epidemic was summarized in "Proposals on heatstroke prevention based on the COVID-19 epidemic" as follows and was issued on June 1, 2020. Based on the above, we have determined that guidance in clinical practice is necessary not only from the viewpoint of heatstroke prevention, but also from the viewpoint of medical treatment. As such, we have created this guidance in the form of supplementary recommendation.