Babies with fever due to viral infections usually have fever symptoms that last about 3-7 days, but the exact duration depends on the condition and the cause of the disease, and needs to be determined on a case-by-case basis. There are various channels of viral infections in children, such as respiratory, digestive, and urinary tracts. For example, viruses of the respiratory tract include influenza virus, cold virus, adenovirus, rhinovirus, or herpes virus. There is no absolute fixed date for how long a viral infection fever lasts, as the viruses themselves can vary in virulence and the child’s own immunity. Viral infection fever is the result of a tug-of-war between the external virus and the body’s immunity. The number of days of illness is a combination of factors that affect the duration of the virus infection. Parents of a child can first reduce the fever by using physical cooling. If the fever does not go away, the child should be examined by a pediatrician as soon as possible and given fever-reducing medication or symptomatic treatment under the guidance of a doctor.