The duration of fever in children with viral infections varies depending on the disease: if the fever is caused by a cold virus, it lasts about 1-3 days, and if it is combined with bronchitis or pneumonia, the fever may last longer. If the fever is caused by influenza virus, the duration is about 3-5 days, and there are cases where the fever lasts longer, reaching more than 1 week. If the fever is caused by a viral enteritis, such as rotavirus, the duration is about 1-3 days. If the fever is caused by hand, foot and mouth disease, it is about 1-7 days depending on the severity of the disease. If the fever from HFMD is more than 3 days, you should be aware of the possibility of severe HFMD.