Fever from viral infections usually lasts about 3-7 days, depending on the individual’s body type, the type of virus, the severity of the infection and the presence of complications. Usually, a common viral infection is a self-limiting disease with a duration of about 7 days. However, the duration of fever varies from person to person, for example, infants and elderly people may have fever for a longer period of time than young adults. In addition, the severity of the disease caused by different types of viruses varies, so the duration of fever also varies, from 3-5 days to 2 weeks, and the fever caused by influenza virus can last 2 weeks or more. The fever caused by influenza virus can last for 2 weeks or even longer. The fever can also last longer if the viral infection is combined with other complications such as pneumonia and otitis media. Therefore, patients should receive regular treatment as soon as possible after the diagnosis of viral infection, and at the same time take care to rest and drink more water.