Most fevers are caused by infection or other illness. Fever itself usually causes no harm and helps the body fight infections by stimulating natural defense mechanisms.
More to Know
In a healthy person, a fever usually isn't a sign of anything serious. Although a high temperature can be frightening, a fever can actually be a good thing when it's in response to an infection or illness. Experts believe turning up the heat makes the body a less comfortable place for germs that cause infections.
Not all fevers need to be treated. High fever, however, can be uncomfortable and worsen problems such as dehydration.
An important exception: An infant 3 months or younger with a rectal temperature of 100.4°F (38°C) or higher needs immediate medical care. Call your doctor or take the baby to the emergency department immediately. Even a mild fever can be a sign of a potentially serious infection in very young babies.
Keep in Mind
Home care (rest, plenty of fluids) often is enough to manage a fever. Acetaminophen or ibuprofen can ease discomfort, but kids or teens should not take aspirin, which has been linked to a rare but serious illness called Reye syndrome.
Someone with a fever should stay home from school, work, or childcare until the temperature has been normal for 24 hours without the use of fever-reducing medicines.
All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.