Fever is a relatively common symptom in pediatric clinics, and nearly 2/3 of pediatric emergency room visits are due to fever. Normal human body temperature is regulated by the thermoregulatory center, and the process of heat production and dissipation is dynamically balanced by neurological and humoral factors to keep the body temperature in a relatively constant range. When the body temperature rises beyond the normal range under the action of thermogenic sources or when the dysfunction of the thermoregulatory center is caused by various reasons, it is called fever. There are many causes of fever, which can be generally divided into infectious and non-infectious fevers, and the most common cause of fever in children is infectious. Infectious fever includes infections of various pathogens, the most common being viral and bacterial infections, while other pathogens such as fungi, tuberculosis, mycoplasma, chlamydia, rickettsia, spirochetes, etc. are relatively rare, and the infections can be acute, subacute, or chronic in origin, and can be localized or systemic. Non-infectious fever is not uncommon in clinical practice and includes the following conditions: 1. Absorption of aseptic necrotic material (also called absorption fever), including tissue injury after major surgery, internal bleeding, large hematomas, massive burns, infarction or limb necrosis of the heart, lungs, spleen and other internal organs, cancer, leukemia, lymphoma, hemolytic reactions, etc.; 2. Antigen-antibody reactions, such as rheumatic fever, serum sickness, drug fever, connective tissue disease, etc.; 3) endocrine and metabolic diseases, such as hyperthyroidism, severe dehydration, etc.; 4) reduced skin heat dissipation, such as extensive dermatitis, ichthyosis and chronic heart failure, etc.; 5) malfunction of the thermoregulatory center. Such as central, poisoning, various intracranial lesions, etc.; 6) autonomic dysfunction, mostly functional hypothermia, such as summer hypothermia, post-infection hypothermia, primary hypothermia, physiological hypothermia, etc. I. How to classify fever and what are its manifestations? The normal body temperature of children is generally 36-37℃ (axillary temperature), and the temperature measured by the anal temperature is generally about 0.5℃ higher than the axillary temperature. There are individual differences in body temperature among children, and the temperature fluctuates throughout the day, rising slightly in the afternoon, after strenuous exercise or eating, but the fluctuation range does not exceed 1℃. Clinically, fever is graded according to the level of fever. A body temperature of 37.3 to 38℃ is considered low fever, 38.1 to 39℃ is moderate fever, 39.1 to 41℃ is high fever, and 41℃ is super high fever. The performance of fever can be divided into the period of rising body temperature, high fever, and falling body temperature. The rising period of body temperature often has fatigue and weakness, general muscle pain and discomfort, cold limbs, pale face, chills and chills, etc. It is especially noted that parents often mistake chills for convulsions, and the body temperature can rise suddenly or slowly during this period, and many children are prone to convulsions during the process of temperature rise. The hyperthermia period refers to a certain period of time after the peak of the temperature rise, the duration of which varies depending on the cause of the disease, the child’s chills disappear, the skin is red and burning sensation, breathing accelerates and deepens, and sweating begins. The body temperature begins to drop, sweating increases, the child likes to drink water and the skin is moist. Second, how do parents deal with fever? Parents are sometimes very nervous about their children’s fever. In fact, fever in children is mostly caused by viral infections, and viral infections are mostly treated symptomatically, and the increase of body temperature is the body’s response to the increase of pyrogenic sources after infection. If the body temperature is below 38.5℃, we suggest that parents should take physical cooling as the main treatment, appropriately lower the ambient temperature, reduce clothing as appropriate, consider cooling paste or ice pillow, ice bag to cool down the body, of course, when the child has chills, you can add clothes and quilts to keep warm, there is another important point, parents need to feed the child more water to increase fluid intake to prevent the occurrence of dehydration. When the body temperature exceeds 38.5°C, parents can consider giving their children antipyretic drugs, currently the main children’s antipyretic drugs are ibuprofen and acetaminophen, aspirin and nimesulide are no longer used in children’s antipyretic drugs due to their serious adverse reactions. Ibuprofen and acetaminophen can be used alternately, and can be repeated at 4-6 hour intervals. Pay special attention to more hydration during the use of antipyretic drugs to avoid excessive sweating causing dehydration symptoms. When to go to the hospital is directly related to parents’ experience. From the medical professional point of view, the first 24 hours of fever do not necessarily mean going to the hospital, as fever is only a symptom of the disease, and whether to go to the hospital depends on the cause of the fever (underlying pathology) and the child’s general condition. If the fever is a general viral infection, it will be fine with symptomatic treatment and is self-limiting. However, since parents do not have the ability to make medical professional judgments about fever in children, it is recommended to go to the hospital promptly when the temperature exceeds 39°C or when the child’s general condition is poor, so that further treatment can be made by medical professionals after the judgment of the primary cause and the assessment of the condition. Parents need not emphasize the need for infusion. It is best to let the doctor decide on the infusion according to the original disease and the severity of the disease or the presence of complications or the general condition of the child, and the use of antibiotics should be decided according to the presence or absence of bacterial infections or the increase of indicators of bacterial infections.