How To Use a Thermometer To Check Fever In Kids

Injuries & First Aid

Do you have a sick child with a fever?

It’s cough and cold season again, and that brings with it the dreaded fever. Boo! I am asked all the time what temperature is considered a fever, how to measure temperature accurately, and when to rush your child to the hospital. The truth is — as far as I am concerned — no one temperature indicates the severity of a child’s sickness. A child can have a very high fever with a viral infection and no fever with a bacterial infection. The fever or body temperature itself is not necessarily a signal that your child needs medication or treatment.


Here’s how to use a thermometer to check fever in kids.

But let’s start with the basics.

There’s several ways to check children’s temperature:

  • Rectally – in the rectum (bum)
  • Orally – in the mouth
  • Axillary – under the armpit
  • Temporal artery – on the forehead or over the temple
  • Tympanic – in the ear

And there are different kinds of thermometers to measure temperature with. So make sure you use the appropriate thermometer in the proper place! But why would we measure body temperature in different places? Well, that would depend on things like the child’s age and the accuracy of the reading. Keep reading for more details.


What is the best way to check for fever in kids?

The most accurate way to take your child’s temperature is in the rectum. This can be challenging for parents or uncomfortable for children, however, so there are other options.

My current favorite way to measure body temperature is by using the Braun No-Touch forehead thermometer. I wasn’t convinced before using it, but I did use it on two of my kids and compared the rectal temperature to the Braun’s forehead temperature, and it was VERY close. The forehead thermometer is now my go-to for its ease of use and comfort for the child. I don’t even have to touch it to their skin when they are sleeping!

But in general, I tend to avoid tympanic temperature measurements, as I find them to be less accurate. For example, if your child has an ear infection, one ear may register a temperature that indicates a fever, and the other may read a normal temperature. Additionally, fever strips — adhesive strips placed on the forehead — are convenient for a sleeping child but can be inaccurate, so I avoid those. Children older than five years can usually allow an oral temperature, which is accurate and painless. Of course, ensure you have cleaned your thermometers thoroughly, as many rectal thermometers can double as oral or axillary (armpit) thermometers, which can be gross and unsanitary if not cleaned properly.


What is a normal temperature for children?

The normal temperature range for children varies depending on what method you are using to take the temperature.

•  Rectal  – 36.6°C to 38°C (97.9°F to 100.4°F)
•  Ear  – 35.8°C to 38°C (96.4°F to 100.4°F)
•  Oral  – 35.5°C to 37.5°C (95.9°F to 99.5°F)
•  Axillary  – 34.7°C to 37.3°C (94.5°F to 99.1°F)


What temperature is a fever?

•  Rectally  – above 38 °C or 100.4 °F
•  Orally  – above 37.5 °C or 99.5 °F
•  Axillary or tympanic  – above 37.3 °C or 99.1 °F


Some simple rules of thumb:

  • Avoid using mercury thermometers – if they break, you may expose your child to this toxic substance.
  • Treat discomfort more than the temperature measurement. My children often have low-grade fevers and feel fine physically. I treat their discomfort and pain, and the number on the thermometer is less critical for me.
  • Ensure your child is drinking enough water. Their appetites may be suppressed when they’re not feeling well, and that is ok. As long as your child is drinking small amounts often, hydration should be maintained.
  • See your doctor if your child looks unwell, is not drinking, is sleeping excessively, or has a fever for more than 72 hours. This may require a diagnosis.


Is there a dangerous body temperature range?

Yes, of course. A human body is not functioning optimally above 40 °C or 104 °F. Your child may be lethargic or incoherent with fast breathing and a quick heart rate. With this body temperature, most children look unwell.



Dr. Dina Kulik

Dr. Dina Kulik

The general information provided on the Website is for informational purposes and is not medical advice.

Do NOT use this Website for medical emergencies.

If you have a medical emergency, call a physician or qualified healthcare provider, or CALL 911 immediately. Under no circumstances should you attempt self-treatment based on anything you have seen or read on this Website. Always seek the advice of your physician or other licensed and qualified health provider in your jurisdiction concerning any questions you may have regarding any information obtained from this Website and any medical condition you believe may be relevant to you or to someone else. Never disregard professional medical advice or delay in seeking it because of something you have read on this Website.

Subscribe To Our Newsletter

Join our mailing list to receive the latest news and updates from our team.

You have Successfully Subscribed!

Subscribe To Our Newsletter

Join our mailing list to receive the latest news and updates from our team.

You have Successfully Subscribed!

Success! Check Your Inbox

Success! Check Your Inbox

Success! Check Your Inbox