Fever in children usually lasts for 2-3 days, a week or more, and can be caused by two main reasons: 1) infection and 2) autoimmune system. For infection is more common, may be infected with viruses, bacteria or other mycoplasma, microorganisms, etc., can cause a certain fever phenomenon, and sometimes some immune system diseases can also cause the fever phenomenon. If the temperature is not particularly high, below 38.5 ℃, generally do not need much intervention, you can reduce the fever through physical cooling methods and antipyretic paste; if the temperature is higher, you need to use the appropriate drugs to treat. If the disease of autoimmune system should be paid attention to, you can go to the hospital for the corresponding examination to make the right medicine.