How to use Digital Thermometer: Oral, Axillary and Rectal?

Written by: Kaushik Jethva

Last Updated: November 30, 2022

steps to use a digital thermometer
A man holding a digital thermometer in his hands.

Did you know, the spot where we measure temperature readings and how to use digital thermometer differs age by age?

Digital thermometers are the most common thermometer types which are used widely all over the world. A digital thermometer determines the body temperature by using heat sensors. With a digital thermometer, you can take temperature readings in the mouth, rectal area, or under the armpit.

Digital thermometers can take the highest temperature readings as compared to any other type of thermometer in the market. It will continue to read temperatures even after the beep until the temperature stabilizes.

Note: Keep in mind that the (axillary) armpit temperature generally runs ½ to 1 degrees F or 0.6 Celsius cooler than oral temperatures. Whereas the rectal temperature runs ½ to 1 degree F or 0.6 Celsius warmer than oral temperatures.

1 How to use Digital Thermometer: Things to keep in mind

Step – 1: When you turn the thermometer on, you will see low symbol on the display. This low symbol is normal and does not mean the battery is low. It simply indicates low temperature which is normal since the tip is exposed to the air and not in contact with any part of the body.

Step – 2: Once you use the thermometer to take oral, axillary, or rectal readings, it will take the reading normally. If the digital thermometer is giving cold readings due to the ambient temperature being cold, hold it in for 30 seconds.

Step – 3: Before taking temperature readings you must check the battery. You can easily find out if the battery of digital thermometer is low. The low battery symbol resembles an inverted T.

Step – 4: Incase you want to change the temperature scale from Fahrenheit to Celsius, the first step is to ensure that the digital thermometer is switched off with On/Off button. While the thermometer is switched off, press and hold the On/Off button until it shows a small F or C symbol at the top right of the display. This usually takes about 2 to 4 seconds.

2 How to use digital thermometer?

For oral temperatures

how to take oral temperature readings with a digital thermometer
A boy holding a digital thermometer in his mouth and taking oral temperature readings.

A digital thermometer gives the most rapid and accurate readings when used orally.

Step – 1: Before taking an oral temperature reading, make sure to reset the digital thermometer with the reset button. If you do not reset the thermometer, it will display the last recorded temperature reading.

Step – 2: While reading an oral temperature, make sure you do not drink or eat anything before 30 minutes.

Step – 3: Place the digital thermometer deep under towards the back and center of your tongue and close your lips firmly. The reading usually takes 10 to 15 seconds.

Step – 4: Keep your mouth closed around the thermometer for the recommended time limit or until the thermometer starts to beep.

Step – 5: Take the thermometer out of your mouth gently and carefully. Read the temperature displayed on the screen.

Step – 6: For further uses, wipe the thermometer with an antiseptic and clean it with warm water.

To measure axillary temperatures

how to take axillary temperature reading with a digital thermometer
A nurse taking axillary temperature readings with a digital thermometer.

You can also place the digital thermometer under your armpits for taking temperature readings. However, armpit temperatures tend to be less precise than oral temperatures.

Step – 1: Reset the digital thermometer. Once the thermometer is reset, you can now power on the digital thermometer.

Step – 2: Gently place the thermometer beneath your armpit. Ensure that the thermometer touches your skin rather than the clothing.

Step – 3: Make sure you hold the thermometer tightly until you hear it beep, which indicates it has reached the correct temperature.

Step – 4: Remove the thermometer carefully and observe the temperature reading on the display.

Step – 5: For further uses, wipe the thermometer with an antiseptic and clean it with warm water.

To get rectal temperatures

how to take rectal temperature readings for babies with a digital thermometer
A digital thermometer used for taking rectal temperature readings of a baby.

The temperature of a small baby is usually measured by rectal method. In order to take a rectal temperature, you will need a digital thermometer and lubricant.

Step – 1: Apply a water soluble lubricant like lube or KY – Jelly to the end of thermometer. You can also use petroleum jelly which can be easily available at your home.

Step – 2: Lay the child carefully on his/her stomach and gently spread apart the buttocks. You can also place the child on their backs with their knees raised up.

Step – 3: Gently and carefully slide the bulb end of the digital thermometer into the anal canal. Make sure the bulb end do not reach further than 1 inch.

Step – 4: Hold the thermometer in place for at least 1 minute until it beeps.

Step – 5: Remove the thermometer carefully and note the temperature readings.

Step – 6: Use rubbing alcohol or an alcohol-based wipe to disinfect the digital thermometer.

If you are looking for a no contact option for taking temperature readings, you can check our blog on how to use an infrared thermometer.

3 Wrapping Up

The first step for a keeping your body healthy and free from any cold or fever is to eat healthy food. However, if someone in your family catches a ever, it is necessary to accurately measure their temperature to diagnose their illness more effectively. Having a doctor recommended digital thermometer and knowing how to use digital thermometer at home makes this task easier for you.

We hope that our step-by-step guide helped you out while using a digital thermometer for your family members. If you face any difficulty performing these steps, please leave a comment and let us know in the comment section.

FAQ's about Digital Thermometers

Which is more accurate a digital or regular thermometer?

Laboratory and clinical studies found that electronic thermometers had more fluctuations of temperature readings than other types of thermometers; however, there was no difference in the average accuracy between the two types of thermometers. Mercury thermometers are no longer recommended because the glass can break easily and the mercury inside is toxic.

It is better to use a digital thermometer because it can provide faster and more accurate results than a regular thermometer. When compared to a mercury thermometers, digital thermometers give you fast results because you don’t have to wait for the mercury to heat and then slowly rise to display the temperature.

You can use a digital thermometer at various spots to determine the temperature of a person. However, the most accurate temperature measurement is the rectal temperature as we discussed above, the rectal temperatures are more warmer.

The forehead temperature is the second most accurate. When done correctly, oral and ear temperatures can also give accurate results but, armpit temperatures are the least accurate.

It is natural for your body’s temperature to rise and fall many times in response to several consecutive measurements. Depending on how long you’ve been awake, moving, and if you’ve stood up, your basal body temperature fluctuates.

So, we recommend you to take the temperature measurements in ideal conditions and read the first taken temperature readings.

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Kaushik Jethva
Written by: Kaushik Jethva author

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Updated: November 30, 2022
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