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Body Temperature

How It Feels

Taking your temperature by mouth is only mildly uncomfortable, since you must keep your mouth closed and breathe through your nose while the thermometer is in place.

Taking a rectal temperature can be slightly uncomfortable but should not be painful.

Taking your temperature with an ear thermometer causes little or no discomfort. It is not inserted very far into the ear, and it provides a reading in only a few seconds. For this reason, the ear thermometer is widely used in doctor offices and hospitals. But it may be less accurate than rectal thermometers.

Taking your temperature with a thermometer that is placed on the skin, such as a plastic strip thermometer or a temporal artery thermometer , should not cause any discomfort. Use of a plastic strip thermometer feels like having an adhesive bandage on your forehead. The slight pressure of a temporal artery thermometer as it glides across the skin is not painful.


There is very little risk of complications from taking a temperature.

When taking a rectal temperature, do not insert the thermometer into the rectum more than 0.5 in. (1.25 cm) to 1 in. (2.5 cm). Further insertion can be painful and may damage rectal tissues.


Body temperature is a measure of the body's ability to generate and get rid of heat.

When you tell your doctor about your temperature measurement, be sure to mention whether it was taken on the forehead or in the mouth, rectum, armpit, or ear.

Body temperature

The average normal temperature is 98.6 °F (37 °C). But "normal" varies from person to person. Your temperature will also vary throughout the day, usually being lowest in the early morning and rising as much as 1°F (0.6°C) in the early evening. Your temperature may also rise by 1°F (0.6°C) or more if you exercise on a hot day. A woman's body temperature typically varies by 1°F (0.6°C) or more through her menstrual cycle, peaking around the time of ovulation.


Oral, ear (tympanic), rectal, or temporal artery temperature

  • Fever: 100.4 °F (38 °C) to 103.9 °F (39.9 °C)
  • High fever: 104 °F (40 °C) and higher

Armpit (axillary) temperature

  • Fever: 99.4 °F (37.4 °C) to 102.9 °F (39.4 °C)
  • High fever: 103 °F (39.5 °C) and higher

A rectal or ear temperature of less than 97 °F (36.1 °C) means a low body temperature (hypothermia).

What Affects the Test

Inaccurate temperature readings can be caused by:

  • Not keeping your mouth closed around the thermometer when taking an oral temperature.
  • Not leaving a thermometer in place long enough before reading it.
  • Not putting the proper thermometer in the right place.
  • Not following the instructions for proper use that come with the thermometer.
  • A weak or dead thermometer battery.
  • Taking an oral temperature within 20 minutes after smoking or drinking a hot or cold liquid.
  • Taking a temperature by any method within an hour of exercising vigorously or taking a hot bath.

WebMD Medical Reference from Healthwise

Last Updated: November 07, 2013
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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