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    Body Temperature

    Why It Is Done

    Body temperature is measured to:

    • Check for fever.
    • Check for a very low body temperature in people who have been exposed to cold.
    • Check for a very high body temperature in people who have been exposed to heat.
    • Find out how well a fever-reducing medicine is working.
    • Help a woman plan for pregnancy by finding out if she is ovulating.

    How To Prepare

    Take your temperature a few times when you are well. This will help you find out what is normal for you. Check your temperature in both the morning and evening. Body temperature can vary by as much as 1°F (0.6°C) during the day.

    Before you take your temperature:

    • Wait at least 20 to 30 minutes after you smoke, you eat, or you drink a hot or cold liquid.
    • Wait at least an hour after hard exercise or a hot bath.

    There are different types of thermometers.

    • Electronic thermometers camera.gif are plastic and shaped like a pencil. They have a display window at one end and the temperature probe at the other end. These thermometers can be used in the mouth, rectum, or armpit. They are easy to use and easy to read. If you buy this type of thermometer, check the package for information about its accuracy.
    • Ear thermometers camera.gif are plastic and come in different shapes. The small cone-shaped end of the thermometer is placed in the ear. Body temperature is shown on a digital display. The results appear in seconds. Some models also show what the oral and rectal readings would be.
    • Temporal artery thermometers have a small "cup" that is moved across the skin over the artery in the forehead. When used correctly, these thermometers are accurate.
    • Disposable thermometers are thin, flat pieces of plastic with colored dots and temperature markings on one end. The color of the dots shows the temperature. These thermometers can be used in the mouth or rectum. A patch form can be used on a baby's skin to measure temperature for 48 hours straight. These thermometers are not as accurate as electronic or ear thermometers.
    • Forehead thermometers are thin pieces of plastic with numbers on them. You press the strip against a person's forehead. The temperature makes some numbers change colors or light up. These thermometers are not very accurate.
    • Pacifier thermometers are shaped like a baby's pacifier. They have a display that shows the temperature. You place the pacifier in your child's mouth to measure temperature. These thermometers may take longer to get a reading and are not as accurate as other types.

    Glass thermometers that contain mercury are not recommended. If you have a glass thermometer, contact your local health department to find out how to dispose of it safely. If you break a glass thermometer, call your local poison control center right away.

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    WebMD Medical Reference from Healthwise

    Last Updated: May 22, 2015
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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