Pediatric fever is a self-protective mechanism that mobilizes the whole body immune system to fight the disease. The temperature is closely related to the child’s physical condition, nutritional status, time (such as morning and evening, four seasons), but not to the severity of the disease, that is, not the higher the temperature, the more serious the disease, sometimes repeated high fever for 3-5 days is very common, so in the process of reducing fever, we should actively look for treatment of the original disease, do not simply focus on reducing fever. I. When to apply antipyretic drugs? A fever is defined as a fever when the axillary exceeds 37.3°C (or 37.5°C). It is further divided into low fever 37.4~38°C; medium fever 38.1-39°C; high fever 39.1-41°C; ultra-high fever: 41°C or more. A fever of ≤1 week is considered acute fever. For patients with a temperature below 38.5°C, if they are in good spirits, they can suspend the use of antipyretic drugs, and physical cooling is sufficient. For patients with temperatures above 38.5°C, antipyretic drugs need to be applied to reduce energy consumption and avoid complications such as hyperthermia. The World Health Organization (WHO) recommends two classic oral antipyretics with high safety in pediatrics: “acetaminophen” and “ibuprofen”. 1. Acetaminophen (paracetamol, Tylenol): preferred, for children over 3 months of age. Regular dosage for children: 10-15mg/kg/dose orally, once every 4-6h; less than 5 times every 24h for children aged 3-12 yrs. Rectal administration is no longer recommended in pediatrics. Acetaminophen has a high safety profile at reasonable doses, with occasional nausea, vomiting, sweating, and abdominal pain, and a few cases of dermatitis, granulocytopenia, and thrombocytopenia. Excessive doses can cause liver damage. It is contraindicated in severe hepatic and renal insufficiency. Use with caution in children with liver disease or viral hepatitis, hepatic or renal insufficiency, severe cardiopulmonary disorders, and G-6-PD deficiency. Some compound preparations often contain the ingredient “acetaminophen”, such as aminoglutethimide granules, aminophenflavonamil granules, aminoglutethimide syrup, phenomethimide suspension, etc., but paracetamol and tylenol are single preparations. Be sure to avoid repeated medication when taking them. 2. Ibuprofen (Merlin): For children over 6 months of age. Single preparations include Merlin, Fenbuterol, etc. The recommended dosage of ibuprofen for children is 5-10mg/kg every 6 hours, up to 4 times every 24h. Ibuprofen has a strong antipyretic effect, and the process of reducing fever may cause the body to sweat a lot. Therefore, when using ibuprofen to reduce fever, attention should be paid to whether the child is dehydrated or has insufficient intake, and if necessary, intravenous rehydration can be used. Also, ibuprofen is excreted through the kidneys, so it should be used with caution in patients with poor kidney function. Children with G-6-PD deficiency can use “ibuprofen”. 3.Lysine: It is a compound salt of aspirin and lysine, and its mechanism of action is the same as that of aspirin. It is administered intravenously or intramuscularly to reduce or avoid the occurrence of gastrointestinal reactions, with strong antipyretic effect, fast onset of action and mild effect, and can be used as a common drug for reducing fever in pediatrics. It is used for children who are prone to fever convulsions and cannot be administered orally. However, long-term application may induce the possibility of Richter’s syndrome, and even induce anaphylaxis and severe asthma attacks. Used for intravenous antipyretic, the dose is generally 10-20mg/kg, not more than 4 times in 24 hours, the interval should not be less than 4h. 4, aspirin: traditional antipyretic and analgesic drugs, the World Health Organization does not recommend aspirin routine use for pediatric antipyretic, it is recommended to use other categories of antipyretic drugs. China’s pediatrics has basically not used such drugs for antipyretic, only for the treatment of some special diseases, such as Kawasaki disease, rheumatic fever, juvenile arthritis, etc. 5, diclofenac: a new type of potent anti-inflammatory and analgesic, it exerts its pharmacological effects by inhibiting prostate synthesis, has anti-rheumatic, anti-inflammatory, analgesic and antipyretic effects, analgesic, anti-inflammatory and antipyretic effects are 2 to 2.5 times stronger than indomethacin, 26 to 50 times stronger than aspirin, strong, less adverse reactions, small dose, small individual differences, used for fever caused by various inflammatory diseases. There are views that children under 14 years of age are prohibited. 6, Nimesulide: new non-steroidal anti-inflammatory, analgesic, antipyretic, pharmacological effect is to inhibit cyclooxygenase activity, blocking the biosynthesis of prostaglandin-like substances, leukocyte mediator release and polymorphonuclear leukocyte oxidation reaction, so as to play an antipyretic, anti-inflammatory effect, for fever caused by upper respiratory tract infections, the effect can last 6 to 8 hours. 2011 February media reported a number of fatal cases In May 2011, the State Drug Administration issued a notice restricting the use of Nimesulide, “prohibiting its oral formulation for children under 12 years of age”. Children with persistent high fevers that do not subside may alternate between acetaminophen and ibuprofen if a single drug is not effective in reducing the fever. Alternate the two drugs at least 2 hours apart. When alternating, the maximum number of times each drug can be used is still 4 times a day. Drink more water when taking medication to reduce fever to speed up excretion and help take away body heat. At the same time, it is also necessary to take medicine to reduce fever along with physical means of cooling, which includes taking a warm bath or wiping the whole body with a hot wet towel, and not using alcohol, which can easily pass through the child’s tender skin and lead to alcohol poisoning. Avoid the simultaneous use of multiple antipyretic drugs, increasing the risk of side effects. (1) Pediatric thermoregulatory center is not perfect, so pediatric antipyretic should be based on physical cooling. (2) Fever is a manifestation of the body’s resistance to disease, and should actively find the cause and treat the primary disease. (3) Master the active ingredients, drug action characteristics, adverse reactions, contraindications, and contraindications of various antipyretic and analgesic drugs to prevent damage to the body due to improper use of drugs. (4) According to the characteristics of pediatric antipyretics, reasonably grasp the use interval of pediatric antipyretics. (5) The dosage should be taken on time and in accordance with the dosage, do not arbitrarily increase the dosage or shorten the interval of administration. (6) During the period of fever reduction, the child should be advised to drink more water to avoid deficiency due to profuse sweating. (7) Generally use one kind of antipyretic drugs, and consider combining them when the efficacy is really unsatisfactory. Check the body temperature about one hour after each dose to judge the effect of antipyretic. (8) Reasonable control of the use of the course of treatment, the fever is stopped. (9) Pay attention to the toxic side effects of drugs, such as changes in blood picture, gastrointestinal reactions, liver and kidney function damage, etc. (10) If necessary, subhypnotic therapy can be used for children with severe and persistent high fever.