How to read an oral thermometer

Written by sondra crane
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How to read an oral thermometer
Learn to read the temperature on an oral thermometer. (Gianluca Rasile/iStock/Getty Images)

Taking temperatures using an oral thermometer is not difficult, especially if you're using a digital thermometer. Make sure the tip of the thermometer is wiped clean with an alcohol wipe to sterilise it. Depending on what type of digital thermometer you use, there should be a little button on the top that you touch to clear any numbers that are visible on the screen of the thermometer.

Things you need

  • Thermometer
  • Alcohol wipes

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  1. 1

    Taking the temperature of someone who feels sick is important. An elevated body temperature can indicate infection.

  2. 2

    Make sure the person hasn't eaten or drunk anything hot or cold in the past half hour, because this will skew the temperature reading.

  3. 3

    Place the tip of either digital or oral thermometer beneath the tongue on either side, with the tip pointing to the rear facing the tonsil area. Once the thermometer is correctly placed under the tongue, wait a few seconds for the digital reading, and three minutes for the clinical thermometer reading.

  4. 4

    Make sure that the thermometer is held in place by the patient's lips, tongue or fingers. Have him keep his mouth shut. If you are taking a young child's temperature ask him to hold the thermometer in place with one of his fingers, making sure that he does not use his teeth.

  5. 5

    Wait a few seconds until you hear a beep from the thermometer. Read the numbers in the thermometer's little window. A reading of anything over 37.6 degrees C (99.5F) is fever.

Tips and warnings

  • If you are unsure of how to use a digital oral thermometer, read the instructions or ask your GP.
  • Keep a thermometer in the house. Children especially are prone to getting colds or having a fever.
  • Use an old-fashioned clinical or mercury thermometer in the same way, but it takes longer for the temperature to rise. Leave it in at least three minutes before reading.
  • Read a regular thermometer by waiting for the line of the mercury to stop rising.
  • Make sure you call a doctor if the patient has a very high temperature. A temperature of 38.3 degrees C (101F) and rising might need medical attention. Any temperature over 39.4 degrees C (103F) is serious.

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