High fever, is a common manifestation of disease, especially infectious diseases. To recognize hyperthermia from two aspects: 1, hyperthermia itself can cause increased heart rate, shortness of breath, chills and cold extremities, etc., for the body to treat the normal reaction to fever, body temperature drops after the above conditions improve; 2, looking for the cause of hyperthermia. Often respiratory or gastrointestinal tract infections, the common etiology is a virus. Do not judge the severity of the disease by the degree of hyperthermia, but rather the severity of respiratory or gastrointestinal symptoms for the initial judgment of the disease. Look for the cause of high fever and use cause-specific treatment. Usually in case of infection, high fever lasts for 3-5 days. In high fever, coldness in the hands and feet, these distal parts of the body, is a normal reaction of the body in fever. Regardless of whether the hands and feet are cold or not, if the body temperature exceeds 38.5°C, the child should be given antipyretic medication. The body temperature mentioned here is the temperature inside the body, not the temperature at the ends of the limbs. Therefore, by taking the temperature measured in the ear cavity, armpit, mouth, anorectum and other parts of the body as the benchmark. High fever is the most common fall and winter symptom in infants and children, often appearing earliest and may be accompanied by diarrhea and cough. When fever is high, the body produces more heat than it dissipates, and the body consumption increases, which may cause convulsions in infants and children, so it is important to consider reducing fever regardless of the cause. When the body temperature exceeds 38.5°C, the child should be treated with antipyretic drugs such as acetaminophen or ibuprofen. The goal is to avoid febrile convulsions and to reduce the body consumption caused by high fever. A body temperature of less than 38.5°C activates the immune system and facilitates the control of infections. The use of antipyretic drugs is usually only able to control high fever within 4-6 hours. In order to increase the effect of antipyretics, it is important to encourage more water intake so as to increase skin heat dissipation, increase urination, etc., to achieve the effect of temperature control. Since high fever due to general infection can take up to 3-5 days, antipyretic drugs will be taken repeatedly during this period. In order to reduce the side effects of antipyretic drugs, two types of antipyretic drugs, acetaminophen and ibuprofen, can be used alternately. The most commonly recommended antipyretic medications for infants and children with high fever include acetaminophen and ibuprofen. The common dosage form is an oral syrupy liquid. Some children with fever will not accept oral syrupy liquids. Consider using “acetaminophen” suppositories. Since suppositories are also acetaminophen, they have the same onset of action as the oral form, lasting 3-4 hours. Antipyretics only shift the temperature center (temperature setting point) in the brain downward to increase heat dissipation. Heat dissipation is accomplished through physiological processes such as evaporation of water from the skin and urination. If there is not enough water in the body, the temperature drop is small. This is one of the reasons why people often say that antipyretics are not effective. Therefore, for infants and children with high fever, while taking antipyretic drugs, it is necessary to increase the intake of water, otherwise the effect of reducing fever will become less and less significant. Since fever is often caused by upper respiratory tract infections, it is difficult for children to get water, so parents must be patient. For children who have great difficulty in getting water, and whose fever is difficult to control, intravenous fluids may be considered. But not necessarily antibiotics. There are two forms of fever reduction: one is a gradual decrease in body temperature and a gradual lengthening of the fever interval, and the other is still a high fever but with a gradual lengthening of the interval. A lower body temperature or a longer interval only means that the condition begins to improve. Only when the body temperature returns to normal (body temperature <37.5℃ for a sustained period) is the recovery period considered.