A low-grade fever, or “hypothermia,” is defined as an axillary temperature of 37.3 to 38 degrees Celsius. We usually take the human axillary body temperature as the standard, the normal body temperature is 36-37 ℃, low fever is 37.3-38 ℃, moderate fever is 38.1-39 ℃, high fever is 39.1-41 ℃, and ultra-high fever is more than 41 ℃. Fever, normatively known as “fever”, is a symptom caused by an infectious or non-infectious factor that produces a pyrogen, which acts on the body’s thermoregulatory center, leading to its dysfunction and causing the body temperature to exceed the normal range. Fever is the most common clinical symptom, it is an important early warning of certain diseases, but also the body’s resistance to disease as a defense reaction. Some unexplained fever or non-high fever, can not blindly fever, need to actively find the cause of the disease, for the cause of the treatment, otherwise it is easy to cover up the disease. There are many causes of fever, if you feel unwell, you need to consult a doctor in time, do not treat yourself. In order to avoid delaying the condition.