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

Causes

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.

Treatment

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.