Most of the sudden fever in children is a viral infection, through the child’s physical examination and blood test routine can be clear fever is caused by viral infection. Most common viral fevers in children are pediatric viral colds, which are a self-limiting disease and can be treated symptomatically, with a temperature of more than 38 degrees 5 to take antipyretics and less than 38 degrees 5 for physical cooling. The fever caused by viral cold may last for about 1-7 days, mainly related to the child’s resistance, the type of virus infected and the pathogenic power of the virus. For example, the common fever caused by the early childhood emergency rash is fever for three days, and the fever caused by the flu virus may last for 5 to 7 days. In general, if a fever caused by a viral infection does not subside after more than 5 days, you need to take your child to the hospital as soon as possible for a thorough examination to see if there is a combination of bacterial infections or some special types of viral infections, such as infectious mononucleosis caused by EBV, which can have a persistent fever for up to 1 to 2 months. Most viral fevers are self-limiting and usually require only symptomatic treatment. If the fever persists for more than 5 days, go to the hospital as soon as possible.