Normal body temperature changes in response to many conditions. Measuring body temperature is necessary to find and document abnormal temperature. There are many methods to measure body temperature.
What most people think of a “normal” body temperature [which is an oral temperature of 98.6°F] is an average of normal body temperatures in a large population of people. An individual person’s temperature may actually be 1°F (0.6°C) or more above or below 98.6° F.
Your normal body temperature changes by as much as 1°F (0.6°C) throughout the day, depending on how active you are and the time of day. Body temperature is very sensitive to hormone levels and may be higher or lower when a woman is ovulating or having her menstrual period.
A rectal or ear (tympanic membrane) temperature reading is 0.5 to 1°F (0.3 to 0.6°C) higher than an oral temperature reading.
A temperature taken in the armpit is 0.5 to 1°F (0.3 to 0.6°C) lower than an oral temperature reading.
This is the most common method of taking body temperature.
The person should be mature enough to cooperate and follow instructions. He should not have taken any hot or cold stuff for some time.
For accurate measurement, it is important that the person whose temperature is to be taken should be able to breathe through the nose.
If the nose is stuffy or patient does not cooperate, the reading would be faulty. In such cases, it is always better to use other methods.
- The person is asked to place the thermometer under the tongue, on to one side of the center. The lips should be tightly closed around it.
- Leave the thermometer in place for the required amount of time. The time period varies from the thermometer to thermometer. Traditionally, the mercury thermometers were kept for three minutes. Keep the thermometer for the required time. Digital thermometers give beeps on completion of reading.
- Check reading on thermometer after taking it out from the mouth after the required time.
- Clean the thermometer with clean water.
- Rectal Method
- This method is recommended for infants, small children and people who are unable to hold a thermometer safely in their mouths. Rectal temperature gives the most accurate measurement of body temperature.
- Apply a lubricant on the bulb of the thermometer. A jelly-like Vaseline would do. This makes the insertion of thermometer easier.
- In the case of children, make the child lie prone on a lap or soft padded surface.
- Spread the buttocks and insert the bulb end of the thermometer about 1/2 to 1 inch into the anal canal. Be careful not to insert the thermometer too far. Prevent the child from struggling, since this can accidentally push the thermometer in further. Remove the thermometer after 3 minutes or when the device beeps. Pressing the child’s buttocks together will help keep the thermometer in place.
- 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.
- Clean the thermometer with cool, soapy water and rinse it.
A thermometer used for measuring rectal temperature should not be used to measure oral temperature.
Though not as accurate as oral or rectal methods, armpit is commonly used as a place for measuring the temperature. It is quite a simple method to execute.
- The thermometer is placed underarm with the bulb in the center of the armpit.
- Press the arm against the body. The usual time for which thermometer is kept is 5 minutes.
- Remove the thermometer and read it. Armpit temperature reading may be as much as 1°F (0.6°C) lower than an oral temperature reading.
- Clean the thermometer with cool, soapy water and rinse it off before putting it away.
For this measurement, one requires special thermometers.
- 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.
- Attach the disposable cover to the probe. Use a disposable probe cover to keep the probe clean. Use a new probe cover each time you take an ear temperature.
- Turn the thermometer on.
- For children < 12 months, pull the earlobe down and back to place the probe in the ear canal. Center the probe tip in the ear and push gently inward toward the eardrum.
- For children >12 months and adults, pull the earlobe up and back.
- Press the “on” button to display the temperature reading.
- Remove the thermometer and throw away the used probe.
Again, specialized devices are required for this measurement.
- Press the soft cup of the thermometer or the entire plastic strip firmly against a dry forehead.
- Hold the thermometer in place for the required time.
- Read the temperature before removing the thermometer. [Note the difference from other methods]
- Clean the thermometer.
Forehead thermometers are not as accurate as other thermometers. In case of high fever, the temperature should be confirmed by other methods.