When your baby has a fever and you're worried, call your doctor. Be prepared to report your baby's temp, the method you used to take your baby's temp, how long your baby has had a fever, and any other symptoms your baby has. Wait to give any child under age 2 acetaminophen (Tylenol) or any fever-reducing medication until your pediatrician gives the OK. Ibuprofen, for example, should not to be given to children under 6 months or who are vomiting or dehydrated. Don't use aspirin to treat your child's fever. It has been linked with side effects such as intestinal bleeding, and most seriously, Reye's Syndrome, a severe neurological disorder.