The distinction between high fever and low fever can be made by measuring the axillary body temperature. The normal axillary body temperature is 36.3-37.2℃, while low fever is a body temperature of 37.4-38℃; the axillary body temperature of moderate fever is 38.1-39℃; the axillary body temperature of high fever is 39.1-41℃. And if the body temperature exceeds 41℃ or more, it is ultra-high fever, which is very dangerous at this time and can easily induce central nervous excitement, abnormalities such as convulsions and even cause failure of various organs. If the body temperature exceeds 38.5℃, it needs to be cooled down with medication under the guidance of a doctor, mainly to prevent the occurrence of hyperthermia and hyperthermia.