Why do people get fever? Actually, fever is a battle between good and evil in the human body. The human body has a complete protective system (immune system) that recognizes itself and eliminates or destroys foreigners. When pathogenic microorganisms (bacteria, viruses, mycoplasma, etc.) enter the body, the human immune system begins to work, automatically recognizes the alien, and kills and eliminates pathogenic microorganisms. White blood cells, the body’s health guards, fight against pathogenic microorganisms, and the heat they emit during the battle gathers, causing the body’s temperature to rise. Fever is a self-protective response of the body. The process of fever in children is also a process of continuous self-improvement of their own immune system, which is boosted by one small stimulus of illness after another. What is fever? Fever is defined as a temperature (axillary temperature) >37.2℃ in adults and >37.4℃ in children. Measurement with a thermometer should be taken after the child has been quiet for 30 minutes and the sweat in the armpits has dried. The influence of crying, breastfeeding, activity, defecation, clothing, environment and other factors should be excluded. How is fever classified? Low fever: 37.5-38 ° C; medium fever: 38.1-39 ° C; high fever: 39.1-41 ° C; ultra-high fever: > 41 ° C Fever benefits to the human body: fever itself is not a disease, but only a symptom of the disease, fever is a normal physiological response of the body, which is conducive to the body’s fight against infections, is a self-protection process. Elevated body temperature makes many pathogenic microorganisms unsuitable for growth and reduces their growth rate, thus reducing the number of pathogens in the body; high temperatures caused by fever will inactivate viral enzymes or toxins; fever speeds up the rate of chemical reactions in the body to increase the level of immune response. The immune system speeds up the attack on pathogens and shortens the process of infection; it promotes the maturation of the immune system; fever makes the patient feel sick, in which case the patient is likely to go to rest, preventing the organism from being further damaged while having more physical energy to deal with the infection. Fever is harmful to the human body: cerebral cortical excitement, irritability, twitching; or highly inhibited, talking nonsense, lethargy; serious cases of coma; heartbeat accelerated, the heart burden increased; increased oxygen consumption; sustained high fever will make the body resistance to decline; increase in basal metabolism; indigestion; dehydration and so on. Often hear parents say: quickly bring down the temperature, do not burn my child. Only a small number of children develop febrile convulsions, or neurological symptoms in children with high fever. In general, fever does not burn the child. Appropriate temperature is favorable for the recovery of the disease, but blindly and rapidly reduce the temperature is very unfavorable to the body.