Rectal Temperature

Taking a rectal temperature of a baby

A rectal thermometer is the most accurate way to take a temperature.

To take a rectal temperature:

  • Apply a lubricant jelly or petroleum jelly, such as Vaseline, on the bulb of the thermometer, so that you can insert it easily.
  • Choose a quiet place so that the child won't be distracted or move around too much. When measuring the temperature of babies or small children:
    • Place your child faceup with legs bent toward the chest with your hand on the back of the thighs or holding the feet as if you were changing a diaper.
    • Place the child facedown on your lap or on a flat covered or padded surface, such as a bed.
  • Gently insert the bulb end of the rectal thermometer about 0.6 in. (1.5 cm) to 1 in. (2.5 cm) into the anal canal. 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).
  • Leave the thermometer in place for the required amount of time, usually a minute. Some digital thermometers give a series of short beeps when the reading is done. Time yourself with a watch or clock.
  • Remove the thermometer and read it.
  • Clean a digital thermometer with cool, soapy water, and rinse it off before putting it away.
  • After a thermometer has been used to take a rectal temperature, do not use it to take an oral temperature.

Current as of: July 1, 2021

Author: Healthwise Staff
Medical Review:
Susan C. Kim MD - Pediatrics
Adam Husney MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Kathleen Romito MD - Family Medicine
John Pope MD - Pediatrics
David Messenger MD - Emergency Medicine, Critical Care Medicine

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