A Moms Guide to Thermometers

Why are there so many different types of thermometers? No, seriously. There is. There are ear (tympanic), forehead (temporal), or multi-use thermometers (for oral, rectal, or digital – but make sure to buy a separate one for rectal… 🙂).

Is one better than the other? Are some more accurate? Lets take a look at the different type of thermometers available on the market and which one might be the best option for your family.

Disclaimer: this is not medical advice. This blog is for informational purposes only. Please direct any health questions to your care provider.

A reminder: Use a digital thermometer

We’re living in 2021 so I’m sure most people are using digital thermometers at this point. But just in case you decide to go digging in grandma’s cabinet, mercury thermometers are not recommended. So just get rid of that thing and go buy a digital thermometer – you can get them for pretty cheap on Amazon or at your local drugstore/pharmacy.

Note: if you do actually have a mercury thermometer, you should actually be getting rid of it. Read here to see what should be done if this thermometer happens to break.

When you do need to use a thermometer?

If your child is presenting with symptoms of illness – this can range from crankiness/irritability in a young child, to cold symptoms and beyond. Or if something just doesn’t feel quite right – a mom gut can be a good indicator sometimes!

A thermometer is of course used to check for fever. I did a pretty thorough post on fevers in children here that I highly suggest reviewing in conjunction with this post. In this day and age, you may also need to check your child for fever as precaution – before sending them to daycare for example.

A reminder: a thermometer is the only way to correctly tell if your child has a fever. The ol’ back of your hand on their forehead trick just won’t give you the data you need. Warmth alone is not an indicator of a fever.

Second reminder: although I went over this in my past post – remember that a fever is generally considered 38 degrees Celsius (100.4 degrees Fahrenheit) and above. Please note that in certain situations a doctor or care provider may give you different parameters to follow for certain treatment plants/patient situations – always follow the guidance & recommendations of your care provider.

A chart of normal temperature readings based on location taken can be found here.

What is the best type of thermometer to use for my child?

The “best” thermometer to use depends at an overview level, on two things:

  • The age of your child;
  • The comfort level of the parent

But it also depends on what you have access to. So truth be told – if you only have one type of digital thermometer (or can only gain access to whatever someone else has to lend you), then that is the best option to use at the time.

The Canadian Task Force on Preventative Health recommends:

Some important notes about the thermometer types:

  • Oral – it’s important to remember that because we eat and drink with our mouths, oral temperature readings can be off because of something we recently ingested (think – popsicles when your little one isn’t feeling so hot!). So you’ll want to space out eating and drinking (30 mins approximately) with checking your child’s temperature orally. Make sure your child doesn’t bite down on the thermometer. The thermometer should go under the tongue.
  • Temporal – can be influenced by the temperature outside or by direct sunlight. Specific instructions for these ones vary on what type they are (some are “non-touch”)
  • Tympanic – can also be influenced by cold temperatures outdoors (so space out reading by 15 minutes after being outside in cold weather). Pull ear back & up and place probe into the canal, pointing towards the ear on the other side.
  • Rectal – ask your provider for guidance (some of us are visual learners, you can also check out the AAP’s page here) if you are comfortable pursuing this method of measurement. If you aren’t – it’s TOTALLY ok. Use another method appropriate for your child’s age and although readings vary slightly and can be off – you’ll get a rough idea about your child’s temperature. If you feel something is off despite a normal reading – you can opt to take a rectal or reach out to your provider or if you don’t have one, try contacting a service like Telehealth for further guidance.
    • One reminder is to DEFINITELY put a label on any thermometer you use rectally!! Because.. yeah I’m sure you can figure out where I’m going with this one.
  • Remember to read the instructions for all thermometers.

Each thermometer type has positives and negatives to it. No method of measurement is “perfect”, especially for at home use. A rectal measurement may give the most accurate reading of temperature, but it is not (understandably) a preferred measurement modality for many due to comfort, or concerns about the small risk of rectal perforation if performed incorrectly. An axillary measurement is less accurate, but may be preferred for comfort reasons or accessibility.

At the very least – you should be using one of the options that is appropriate for your child’s age group.

I should mention that the AAP actually does recommend the temporal thermometer for all ages while the Canadian Paediatric Society does not recommend temporal thermometers for at home readings.

A 2017 study did show that the temporal thermometer gave readings that were comparable to rectal in the neonatal population – but the authors did go on to recommend more studies be done before any type of official recommendation be made or updated. Then, a study done in 2018 again comparing rectal and temporal thermometer measurements did not come to the same conclusions (it was a non-randomized study though). The link I’ve provided in this paragraph (here again) contains a table of more recent studies reviewing different temperature taking modalities. Verdict on temporal is: more research needed for in-home use, I’d say. It certainly shows promise, but some studies seem to suggest that accuracy is questionable at times and may be impacted by the user and their ability to use the thermometer.

Verdict: there are recommendations by age group that should be followed to increase accuracy & comfort for your child. Within those parameters – choose an option that is available to you and makes you comfortable. Follow up on any concerns you may have (regardless of the reading) with a provider.

If your child does have a fever, follow any guidance as given by your provider (eg. if it’s after immunizations, etc.) or reach out to them directly if any concerns arise. You can check out the Caring for Kids (CPS) page here on fevers for some additional guidance on when to seek additional help, or my previous post on fevers which contains the same information.

5 responses to “A Moms Guide to Thermometers”

  1. […] For reference, please see my previous posts on misconceptions around fever in babies and children, as well as my post on thermometers. […]


  2. […] Unfortunately, a “mild” fever and a “low-grade” fever are terms you see used but defined differently by different sources. The other issue is that a temperature reading varies depending on where it is taken from (I wrote about that a bit in this post). […]


  3. […] Not sure what type of thermometer to use for your child? Check out this post. […]


  4. […] or if you have concerns about a reading. Review the appropriate thermometer to use based on age here (the best one is always what you’re most comfortable with + what you […]


  5. […] My post: A Mom’s Guide to Thermometers […]


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