Body Temperature

Temperature Measurement

How It Is Done

Before taking a body temperature, review the instructions for how to use your thermometer. Methods of taking a temperature are described below.

How to take an oral temperature

Oral is the most common method of taking a temperature. To get an accurate temperature, the person must be able to breathe through the nose. If this is impossible because of a stuffy nose or lack of cooperation, use the rectum or armpit.

1. Place the digital or disposable thermometer under the tongue, just to one side of the center, and close the lips tightly around it.
2. Leave the thermometer in place for the required amount of time. Time yourself with a clock or watch. Some digital thermometers give a series of short beeps when the reading is done.
3. Remove the thermometer and read it.
4. Clean a digital thermometer with cool, soapy water and rinse it off before putting it away.

How to take a rectal temperature

This is the location to measure body temperature most accurately. It is recommended for babies, small children, and people who cannot hold a thermometer safely in their mouths. It is also used when getting the most accurate measurement is essential.

1. Apply a lubricant jelly or petroleum jelly, such as Vaseline, on the bulb of the thermometer so that you can insert it easily.
2. When measuring the temperature of babies or small children, turn the child face down on your lap or on a flat covered or padded surface, such as a bed. Choose a quiet place so that the child won't be distracted or move around too much.
3. Spread the child's buttocks with one hand and gently insert the bulb end of the rectal thermometer about 0.5 in. (1.25 cm) to 1 in. (2.5 cm) into the anal canal with your other hand. Don't force it into the rectum. Hold the thermometer in place with two fingers close to the anal opening (not near the end of the thermometer). Pressing the child's buttocks together will help keep the thermometer in place.
4. Leave the thermometer in place for the required amount of time. Some digital thermometers give a series of short beeps when the reading is done. Time yourself with a watch or clock.
5. Remove the thermometer and read it. A rectal temperature reading may be as much as 1°F (0.6°C) higher than an oral temperature reading.
6. Clean a digital thermometer with cool, soapy water and rinse it off before putting it away.
7. Do not use a thermometer to take an oral temperature after it has been used to take a rectal temperature.

See a picture of how to take the rectal temperature of a baby.

How to take an armpit (axillary) temperature

Taking a temperature in the armpit may not be as accurate as taking an oral or rectal temperature.

1. Place the thermometer under the arm with the bulb in the center of the armpit.
2. Press the arm against the body and leave the thermometer in place for the required amount of time. Time yourself with a watch or clock.
3. Remove the thermometer and read it. An armpit temperature reading may be as much as 1°F (0.6°C) lower than an oral temperature reading.
4. Clean a digital thermometer with cool, soapy water and rinse it off before putting it away.

How to take an ear temperature

Ear thermometers may need to be cleaned and prepared for use. These steps can be followed when using an ear thermometer; however, follow the instructions for your specific model.

1. Check that the probe is clean and free of debris. If dirty, wipe it gently with a clean cloth. Do not immerse the thermometer in water.
2. To keep the probe clean, a disposable probe cover should be used. Use a new probe cover each time you take an ear temperature. Attach the disposable cover to the probe.
3. Turn the thermometer on.
4. For babies younger than 12 months, pull the earlobe down and back. This will help place the probe in the ear canal. Center the probe tip in the ear and push gently inward toward the eardrum.
5. For children older than 12 months and for adults, pull the earlobe up and back. Center the probe tip in the ear and push gently inward toward the eardrum.
6. Press the "on" button to display the temperature reading.
7. Remove the thermometer and throw away the used probe cover.

How to take a forehead temperature

1. Press the soft cup of the thermometer or the entire plastic strip firmly against a dry forehead.
2. Hold the thermometer in place for the required amount of time. Time yourself with a watch or clock.
3. Read the temperature before removing the thermometer.
4. Clean the thermometer with cool soapy water and rinse it off before putting it away.
5. Forehead thermometers are not as accurate as electronic and ear thermometers. If your baby is younger than 3 months or your child's fever rises higher than 102°F (39°C), recheck the temperature using a better method.

How to use a pacifier thermometer

1. Put together all of the pieces of the pacifier if you need to. Some pacifier thermometers can be used as regular pacifiers and need to have the temperature part attached.
2. Let your child suck on the nipple for the required amount of time. Time yourself with a watch or clock.
3. Remove the pacifier and read the temperature.
4. Clean the pacifier with cool, soapy water and rinse it off before putting it away.
5. Pacifier thermometers are not as accurate as electronic and ear thermometers. If your baby is younger than 3 months or your child's fever rises higher than 102°F (39°C), recheck the temperature using a better method.

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Author:	Maria G. Essig, MS, ELS Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated: March 5, 2007
Medical Review:	Kathleen Romito, MD - Family Medicine Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
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