Home Care of the Sick - How to take the temperature

The usual ways of taking temperature are by mouth (oral) or by the rectum (rectal), and fever thermometers are specialized for these uses. The rectal thermometer has a more rounded bulb to protect the sensitive tissues in the anus. Normal body temperature taken orally is 98.6° F. or 37° C. for most people, but slight variations do occur in the normal range. When the temperature is taken rectally, a normal reading is about 1° F. higher—99.6° F. or about 37.5° C—because rectal veins in the area elevate the temperature slightly.

Before a patient's temperature is taken, the thermometer should be carefully cleaned with soap and water, then wiped dry, or sterilized in alcohol or similar disinfectant. The thermometer should then be grasped firmly at the shaft and shaken briskly, bulb end downward to force the mercury down to a level of 95° F. or lower—or 35° C. or lower if the thermometer is calibrated according to the Celsius temperature scale. See the chart Body Temperature in Degrees for comparative values of the Fahrenheit and Celsius scales.

Body Temperature in Degrees

Body Temperature in Degrees
Fahrenheit Celsius
105.5 40.8
105 40.6
104.5 40.3
104 40
103.5 39.7
103 39.4
102.5 39.2
102 38.9
101.5 38.6
101 38.3
100.5 38.1
100 37.8
99.5 37.5
99 37.2
98 6 Normal 37.0
97;8 Range 36.6

If the temperature is taken orally, the thermometer should be moistened in clean fresh water and placed well under the tongue on one side. If the temperature is taken rectally, the thermometer should be dipped first in petroleum jelly and then inserted about one inch into the opening of the rectum. If an oral thermometer is used in the rectum, special care should be taken to make sure that the lubrication is adequate and that it is inserted gently to avoid irritating rectal tissues. Whichever method is used, the thermometer should be left in place for at least three minutes in order to get an accurate reading.

If circumstances preclude an oral or rectal temperature check, the patient's temperature may be taken under the arm; a normal reading in that area is about 97.6° F. or 36.5° C.

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