Thermometers - How To Use Them

Thermometers - How To Use Them

Which thermometer you use, and how you use it, depends on the age of your child. There are many types of thermometers available.

Key points to remember about using thermometers for children

  • there are a number of different types of thermometers
  • you can measure your child's temperature in different places on their body 
  • how you measure your child's temperature depends on their age and the type of thermometer you have

What sort of thermometer should I use for my child?

Which thermometer you use, and how you use it, depends on the age of your child.

There are many types of thermometers available.

The most common thermometers are digital. You can use these for children of any age. They are easy to use and accurate and are usually the cheapest.

Electronic ear thermometers are expensive and are less accurate in small babies.

How do I use a digital thermometer for my child?

You can use a digital thermometer for your child of any age. A digital thermometer gives a digital reading. There are a number of brands. They are usually the cheapest option. You need to read and follow the instructions that come with your thermometer.

A digital thermometer

Use a digital thermometer under your child's arm if they are under 5 years

Little girl lying on sickbed with digital thermometer under her arm

If your child is under 5 years, you can use the digital thermometer under your child's arm. If you measure the temperature under their arm, it records about half to 1 degree Celsius lower than the core temperature.

To use a digital thermometer under the arm (the axillary temperature):

  • turn it on (these thermometers usually have a button you press to turn on)
  • place the end in the armpit against the skin, and bring your child's arm down over the top of it - it often helps to hug your child to keep the arm down and the thermometer in place
  • most thermometers beep when they have finished measuring your child's temperature 
  • some thermometers also beep while measuring and the beep changes when the thermometer has finished measuring your child's temperature - to avoid confusion, it is worth keeping the thermometer in place for 2 minutes
  • remove the thermometer and read the number on the side - the temperature you read is about half to 1 degree Celsius lower than your child's actual body or core temperature

Measure your child's temperature in their mouth if they are 5 years or older

A boy with a themometer in his mouth

If your child is 5 years of age or older you can try to measure the temperature in their mouth (the oral temperature). Make sure you only use a digital thermometer in your child's mouth.

To use it in the mouth in older children:

Photo showing a thermometer in a child's mouth

  • your child has to be able to cooperate, which usually means they are of school age
  • turn it on
  • place the end in the mouth under the side of the tongue - try to get your child to keep it there
  • some thermometers make beeping noises when they have finished, but it is worth keeping it in place for at least 2 minutes
  • remove the thermometer and read the number on the side - the temperature you read in in degrees Celsius is close to your child's actual body or core temperature

How do I use an ear thermometer for my child?

Mother taking the temperature of her daughter with an ear thermometer

The electronic or infrared ear thermometer is fast and accurate if used correctly. You can use it in older children but not in young babies.

There are a number of brands.  They are more expensive than digital thermometers.

Read the instructions for your thermometer to find out how to turn it on and take the reading. When placing the measuring end in the ear, be gentle. You do not have to push it far into the ear canal, just at the entrance.

How do I use an infrared forehead thermometer for my child?

Infrared forehead thermometers are quick and easy to use, as you simply point them at your child's forehead. But, they are expensive and may not be accurate. They measure the forehead skin temperature which changes a lot with blood flow and room temperature.

Other thermometers which are best to avoid

Plastic strip thermometer

These are plastic strips that you place on your child's forehead - they are not accurate so it's best not to use them.

Mercury-in-glass thermometer

These old-style thermometers are no longer available but some households still have them. Mercury vapour can be toxic if the thermometer breaks, so don't use these thermometers. Consider getting a digital thermometer instead.

Mercury in glass thermometer

Digital thermometer photo by Dony Wardhana on Unsplash.

Mercury thermometer photo by Matteo Fusco on Unsplash.

Ear thermometer photo by Kelly Sikkema on Unsplash.

Digital thermometer under a child's arm - 123rf.com 
Image ID : 38053375

Digital thermometer in child's mouth - 123rf.com 
Image ID: 40272877

Thank you to Dr Greg Williams for providing the image of the thermometer under a child's tongue.

This page last reviewed 26 November 2018.
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