When a newborn has a fever, it’s crucial to identify the cause first rather than rushing to cool down. Causes of fever in newborns can include upper respiratory infections, gastroenteritis, tonsillitis, pneumonia, and infectious diseases. Young children may also experience fever due to urinary tract infections, gastrointestinal issues, and hand, foot, and mouth disease. It is important to consult a pediatrician to determine the cause and receive appropriate treatment. Self-medication is not recommended for infants.