Fever in adults

Infection is a common cause of fever, but other conditions can also bring the heat.

Fever is one of the body's most effective ways of fighting infection.

The average body temperature is 98.6° F (37°C). But "normal" body temperature varies from person to person. It also changes during the day, rising a bit after you eat or exercise. Body temperature is often higher in the afternoon than it is when you wake up in the morning.

Fever means a body temperature of 100.4° F (38°C) or higher. An infection is the most common cause of fever. Examples include the flu, pneumonia, food poisoning, and bladder infection.

Other conditions can also cause a fever. These include diseases that produce inflammation, such as rheumatoid arthritis, reactions to drugs or vaccines, and even certain types of cancers.

Fever symptoms

    People with a fever may also:

    • sweat
    • shiver (chills)
    • have a headache
    • have achy muscles
    • not want to eat
    • break out in a rash
    • be restless
    • feel weak.

    A very high fever can cause confusion, extreme sleepiness, irritability, and seizures.

    Diagnosing the cause of a fever

    To help determine why you have a fever, your doctor will ask you about:

    • other symptoms such as coughing, abdominal pain, vomiting, diarrhea, or pain when urinating
    • recent surgeries or injuries
    • recent vaccinations
    • new drugs you may be taking
    • recent travel, particularly travel abroad.

    Treating a fever

    Fever is part of your body's defense against infection-causing germs. By itself, fever is usually harmless, though a high fever can be miserable. These steps may help you feel better:

    • Drink plenty of fluids to help cool your body and prevent dehydration.
    • Eat light foods that are easy to digest.
    • Get plenty of rest.
    • Take ibuprofen (Advil, Motrin, or others), naproxen, (Aleve, Naprosyn, or others), acetaminophen (Tylenol, others) or aspirin to help relieve head and body aches and lower your temperature.
    • Take a slightly warm, not cool, bath or apply damp washcloths to the forehead and wrists.
    • Dress lightly (even if you have chills).

    If you have a fever over 104°F (40°C) call your doctor. Call your doctor right away if you have a fever along with any of these symptoms:

    • seizure
    • loss of consciousness
    • confusion
    • stiff neck
    • trouble breathing
    • severe pain anywhere in the body
    • swelling or inflammation of any part of the body
    • vaginal discharge that is discolored or smells bad
    • pain when urinating or urine that smells bad