It is recommended to consult a doctor if a child has had a fever for 72 hours, or if their condition does not improve after 7 days. It is important to use a reliable thermometer, such as a rectal thermometer, to accurately measure the temperature. If fever is present, it is advised to give Tylenol every 4 hours, but no more than 5 times in a 24-hour period. Encourage the child to drink plenty of fluids and consider nasal hygiene using saline solutions. If necessary, consult a healthcare professional for further advice or treatment.