A fever is a common sign of illness, but that's not necessarily a bad thing. In fact, fevers seem to play a key role in fighting infections. So should you treat a fever or let the fever run its course? Here's help making the call.

These recommendations are for people who are generally healthy — for instance, those who are not immunocompromised or taking chemotherapy drugs and haven't recently had surgery.

The values listed in the table below are for temperatures taken with rectal and oral thermometers. These thermometers provide the most accurate measurement of core body temperature. Other types of thermometers, such as ear (tympanic membrane) or forehead (temporal artery) thermometers, although convenient, provide less accurate temperature measurements.

Infants and toddlers

Age	Temperature	What to do
0-3 months	100.4 F (38 C) or higher taken rectally	Call the doctor, even if your child doesn't have any other signs or symptoms.
3-6 months	Up to 102 F (38.9 C) taken rectally	Encourage your child to rest and drink plenty of fluids. Medication isn't needed. Call the doctor if your child seems unusually irritable, lethargic or uncomfortable.
3-6 months	Above 102 F (38.9 C) taken rectally	Call the doctor; he or she may recommend that you bring your child in for an exam.
6-24 months	Above 102 F (38.9 C) taken rectally	Give your child acetaminophen (Tylenol, others). If your child is age 6 months or older, ibuprofen (Advil, Motrin, others) is OK, too. Read the label carefully for proper dosage. Don't give aspirin to an infant or toddler. Call the doctor if the fever doesn't respond to the medication or lasts longer than one day.

Children

Age	Temperature	What to do
2-17 years	Up to 102 F (38.9 C) taken rectally for children ages 2-3, or taken orally for children older than 3	Encourage your child to rest and drink plenty of fluids. Medication isn't needed. Call the doctor if your child seems unusually irritable or lethargic or complains of significant discomfort.
2-17 years	Above 102 F (38.9 C) taken rectally for children ages 2-3, or taken orally for children older than 3	If your child seems uncomfortable, give your child acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others). Read the label carefully for proper dosage, and be careful not to give your child more than one medication containing acetaminophen, such as some cough and cold medicines. Avoid giving aspirin to children or teenagers. Call the doctor if the fever doesn't respond to the medication or lasts longer than three days.

Adults

Age	Temperature	What to do
18 years and up	Up to 102 F (38.9 C) taken orally	Rest and drink plenty of fluids. Medication isn't needed. Call the doctor if the fever is accompanied by a severe headache, stiff neck, shortness of breath, or other unusual signs or symptoms.
18 years and up	Above 102 F (38.9 C) taken orally	If you're uncomfortable, take acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin IB, others) or aspirin. Read the label carefully for proper dosage, and be careful not to take more than one medication containing acetaminophen, such as some cough and cold medicines. Call the doctor if the fever doesn't respond to the medication, is consistently 103 F (39.4 C) or higher, or lasts longer than three days.