A four-year-old baby with a fever of 38.5°C can first be given fever-reducing treatment by taking the oral antipyretic drug ibuprofen or acetaminophen, choosing one of the two drugs. After taking the antipyretic medicine, give the child more warm water and let the child sweat, which is conducive to cooling, but be careful not to sweat too much, so as not to cause hypothermia or dehydration. In addition, parents should also pay attention to the fact that if the baby has repeated fever, they must find out the cause of the fever, whether there is a bacterial infection, viral infection, or mycoplasma infection, and whether the infection is in the respiratory tract, digestive tract, or other parts of the body. It is important to take the child to the hospital for relevant tests, such as routine blood tests, C-reactive protein, chest X-ray, etc., and to provide targeted treatment according to the child’s examined cause.