There are many causes of pediatric fever, which can be broadly divided into the following three categories: I. Extrinsic factors: The body temperature of children is affected by the external environment, such as wearing too many clothes when it is hot, drinking too little water, and lack of air circulation in the room. Internal factors: illness, cold, bronchitis, throat inflammation or other diseases. Third, other factors: such as preventive injections, including measles, cholera, diphtheria, whooping cough, tetanus and other reactions. Fever is only one of the symptoms of the disease, not all of them. For children with congenital heart disease, it is more important for parents to understand the cause of their babies’ fever and seek the correct treatment from professionals. Instead of using fever-reducing medication blindly. In cases where antipyretics must be used, there are a few things to keep in mind: when used with probenecid and verapamil and nifedipine, be careful to lower the dose; they should not be taken at the same time as digoxin. Antipyretics are taken at the time of fever, usually no more than 3 to 4 times a day. Antipyretics and diuretics can reduce body fluids and blood sodium, so it is necessary to replenish water and salt in time, and children can be given some sugar saline. Do not rush to reduce fever in babies with fever. There are several reasons for not rushing to reduce fever in children: 1. A body temperature of 37.5 to 38 ℃ is low fever, 38 to 39 ℃ is medium fever, and more than 39 ℃ is high fever. Low or medium fever is good for the growth and development of children. Fever is a reaction of the body to the invasion of viruses or bacteria, this reaction is conducive to the annihilation of invading viruses and bacteria. 2, less than high fever does not use drugs, can be given to physical cooling. If the body temperature reaches 39 degrees or more, medication must be used, and there is no time to lose. High fever lasting too long can cause many important body functions to be dysfunctional; increase the burden on the heart and blood vessels due to high consumption of oxygen and nutrients; excessive brain excitement leading to febrile convulsions or excessive inhibition causing lethargy; digestive disorders; weakened resistance, combined with pneumonia, etc. 3, the side effects of antipyretic drugs, not as a last resort. Whether paracetamol, compound aspirin (APC), or a variety of other antipyretic drugs, are inseparable from aspirin, caffeine, finasteride to synthesize. Therefore, antipyretic drugs have greater side effects: irritate the gastric mucosa, destroy appetite, aggravate gastric ulcers and even bleeding, causing long-term small amounts of gastrointestinal bleeding and thus iron deficiency anemia; cause blood disorders; damage to the liver and kidneys; severe allergic reactions, manifested as exfoliative dermatitis combined with liver and kidney toxicity and death. 4.Physical and pharmacological cooling can be used as appropriate.