Fever, Adult

A person taking their temperature by mouth.

A person holding a forehead thermometer to another person's head.

A fever is a high body temperature that is 100.4°F (38°C) or higher. Brief mild or moderate fevers generally have no lasting effects, and they often do not need treatment. Moderate or high fevers can feel uncomfortable and can sometimes be a sign of a serious problem. Fevers can also cause dehydration because the body may sweat, especially if the fever keeps coming back or lasts a long time.

You can use a thermometer to check for a fever. Body temperature can change with:

Age.
Time of day.
Where the temperature is taken, such as in the mouth, rectum, ear, under the arm, or on the forehead.

Follow these instructions at home:

Medicines

Take over-the-counter and prescription medicines only as told by your health care provider. Follow instructions on how much medicine to take and how often.
If you were prescribed antibiotics, take them as told by your provider. Do not stop using the antibiotic even if you start to feel better.

General instructions

Watch for any changes in your symptoms. Let your provider know about them.
Rest as needed.
Drink enough fluid to keep your pee (urine) pale yellow. This helps to prevent dehydration.
Bathe or sponge bathe with room-temperature water to help lower your body temperature as needed. Do not use cold water.
Do not use too many blankets or wear heavy clothes.
Stay home from work and public places for at least 24 hours after your fever is gone. Your fever should be gone without having to use medicines.

Contact a health care provider if:

You have vomiting or diarrhea that does not get better.
You cannot eat or drink without vomiting.
You have pain when you pee (urinate).
Your symptoms do not get better with treatment or you have new symptoms.
You have a skin rash.
You have signs of dehydration, such as:
- Dark pee, very little pee, or no pee.
- Cracked lips or dry mouth.
- Sunken eyes.
- Sleepiness.
- Weakness.

Get help right away if:

You have shortness of breath or trouble breathing.
You feel dizzy or you faint.
You are confused and do not know the time of day, where you are, or who you are (disoriented).
You have severe pain in your abdomen.

These symptoms may be an emergency. Get help right away. Call 911.

Do not wait to see if the symptoms will go away.
Do not drive yourself to the hospital.

This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.