A four-month-old baby with a fever of 39 degrees Celsius is classified as high fever, and parents are advised to use fever-reducing medication for their children in time, and the fever-reducing medication should be acetaminophen. After taking antipyretics, we should give the child appropriate warm water to drink, let the child sweat, which is conducive to cooling, but the child should not sweat too much, so as not to cause hypothermia or dehydration. In addition, parents should be reminded that the child’s age is small, if repeated fever to be alert to some other diseases, such as pneumonia, sepsis and other diseases, parents are advised to take the child to the hospital to do the relevant examinations, such as routine blood, C-reactive protein, blood culture, chest X-ray, etc., according to the child’s examination of the cause of the disease, targeted treatment.