Fever is a common symptom in infants and children and is a symptom of many diseases. Fever can be caused by either infectious or non-infectious factors. Fever is one of the most effective measures that the body can take to fight disease. When fever is present, the body’s immune system is strengthened. The function of phagocytes, both antibodies and complement, is significantly increased. The average normal body temperature of human body is between 36.2 to 37.3℃ (axillary), beyond this range is fever, below 38℃ is low fever, above 38-39℃ is medium fever, 39-41℃ degree is high fever, 41-42℃ is super high fever, above 42℃ degree is critical temperature. above 42℃ without fever reduction and supportive treatment as soon as possible, lasting for several hours can lead to death. The physiological function of fever in infants and children, if prematurely subjected to physical or pharmacological cooling interventions, the physiological function of fever against disease will be significantly weakened or even lacking, which is detrimental to the recovery of disease. The correct treatment prescription try is that low fever does not need to be treated, drink more sugar water, replenish energy and water, let the body temperature fall naturally, several hours or even a dozen hours of low fever do not need to intervene in human body temperature. Moderate fever can use physical cooling or small doses of medication to lower the body temperature to below 38 ℃ to maintain a low fever is fine. High fever or ultra-high fever will cause the body to quickly run out of energy and cellular mitochondrial function is impaired, resulting in the decay of organ function, it is necessary to replenish energy and reduce the temperature to hypothermia as soon as possible. The combined cooling method can be used, i.e. physical cooling plus medication to lower the body temperature to below 39°C within one hour and below 38°C within two hours, while actively replenishing energy and maintaining electrolyte balance. adrenocorticosteroids, such as prednisone and dexamethasone, are prohibited below 38.5 charges, as they can lead to a decrease in body resistance, delaying and masking the condition. The body temperature center in the hypothalamus is responsible for regulating the balance between the heat produced and the heat given off by the body. When heat is in balance, the body temperature remains stable. If heat production exceeds heat dissipation, the body temperature increases; if heat dissipation exceeds heat production, the body temperature decreases. How is fever generated? The process of heat generation is the process of converting chemical energy into mechanical energy, which is the process of chemical reaction of decomposition and metabolism, and the process of contraction of skeletal muscle, visceral smooth muscle and cardiac muscle in human body. In the exercise state, it is mainly skeletal muscle, and in the quiet state, it is mainly cardiac muscle and smooth muscle of the gastrointestinal tract. Fever during illness is mainly due to the enhancement of catabolism in the body. Heat dissipation processes include: convection, conduction, radiation and evaporation.