I. Basis: “Guidelines for the Diagnosis and Management of Acute Fever of Unknown Aetiology in Children Aged 0 to 5 Years in China (Standard Version)”, “Expert Consensus on the Safe Use of Children’s Respiratory Drugs: Drugs for Cold and Fever Reduction”. II. Physical Cooling: In acute fever, the recommended method is to apply warmth to the body and/or reduce clothing. Because ice water enema causes chills, vasoconstriction, energy consumption and often more serious discomfort, it is not recommended to use ice water enema to reduce fever, unless the clinical appearance of ultra-high fever. Physical cooling is not as effective as antipyretics, but can be used as an auxiliary antipyretic method. When combined with antipyretics, the body temperature decreases faster than antipyretics alone; when high fever, it is recommended to apply antipyretics at the same time combined with the physical cooling method of warm body application. Antipyretics: Acetaminophen and ibuprofen are the most commonly used antipyretics for children. When the body temperature is ≥38.5C and/or there is obvious discomfort, it is recommended to use antipyretics to reduce fever. 1.Physical cooling is recommended for infants and children within 3 months of age. 2. The most suitable antipyretic and analgesic drugs for children are currently considered to be: acetaminophen and ibuprofen, and multiple antipyretic and analgesic drugs taken at the same time should be avoided. For severe and persistent high fever, alternate antipyretics can be used. 3, acetaminophen: children’s regular dose: oral administration, 10-15mg/kg each time, or 1.5mg/O daily, once every 4-6h. 3-12 years old children do not exceed 5 times every 24h, the course of treatment does not exceed 5d, rectal administration, 150-300mg each time, once a day. 2 years old or younger must follow the doctor’s instructions. 4.Ibuprofen: oral: dispersible tablets, suspension: 20mg/kg per day in 3 times; diluted suspension: 20mg/kg per day in 2 times; suspension drops: 5-10mg/kg. times, repeated 6-8h if necessary, not more than 4 times per 24 hours. The recommended dose of ibuprofen is 5-10mg/kg, once every 6-8 hours. 5.Anacin has more side effects, mainly nephrotoxicity, for intestinal bleeding, severe rash, allergic reaction, lethal granulocyte count deficiency and aplastic anemia, and it is not recommended for children. 6, aspirin and other antipyretic agents (acetaminophen and ibuprofen) antipyretic effect is comparable, but increase the risk of gastric ulcer and gastric bleeding; at the same time can affect platelet function, increasing the probability of bleeding; children with viral infectious diseases, increasing the risk of Reye’s syndrome. Aspirin is not recommended as a fever reducer in children. The World Health Organization recommends that aspirin be limited to rheumatic fever, juvenile arthritis, and Kawasaki disease in children. Our atypical pneumonia treatment protocol states that aspirin is contraindicated in children with fever. 7, Nimesulide adverse reactions include hypothermia, gastrointestinal bleeding and liver damage or even failure, and should not be used as the drug of choice to reduce fever. 8. Glucocorticoids have immunosuppressive effects, and their improper use may contribute to the spread of bacterial or viral infections and aggravate the disease.