Best Way to Measure Fever in Kids

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Remember how your Mama used to hold her hand against your forehead to decide if you had a fever or not?

(In fact, I bet you’ve done this a time or two with your own kids…I definitely have!)

**Sooo…is the “hand method”t accurate?**

(*Note: This post may contain affiliate links, which means I might receive a commission, at no extra cost to you, if you make a purchase using those links*)

Or how about those scary rectal thermometers…they send you home with your first baby, and expect you to stick it WHERE to find out if they have a fever?!?!

Or the more “new-fangled” thermometers that scan across their forehead, or poke into their ears…are they worth the added expense?

Of course, don’t forget the standard oral thermometer…which my 4-year old can’t even consistently keep under his tongue yet.

While there are several ways to check your child’s body temperature to see if they have a fever, all ways are not all created equal. And they each come with different temperature ranges as to what even COUNTS as a fever…

DISCLAIMER: I am a Registered Nurse, but I am not your Registered Nurse. The information in this article is basic info that applies to most situations where an otherwise healthy child (or adult) comes down with a relatively common, run-of-the-mill sort of illness. You should always follow your Mama instincts and seek additional help when you need it!

Taking temperature by touch (aka hand)

This is the tool I use when checking my kids temperature by hand. Unfortunately, it is not currently available for sale on Amazon.

Touch is the age-old Mama way to check your child for fever, and it’s legit! It won’t give you a specific number…but fever is simply a number anyway. It’s much more important to observe how your child is acting in order to determine “how sick” they actually are.

The pros of this method are that it’s quick and non-invasive, and can give you an early heads-up that your child is for real not feeling well (versus just pretending so they can get out of doing chores…)

The cons of this method are that the temperature of your child’s skin can also be effected by other factors unrelated to fever…like if they’ve been playing outside, bundled up in a warm bed, or if YOUR hands are icy cold.


One way I get around the “icy hands” problem is by using a “Mama Kiss.” In my experience, I find that my lips usually maintain a more constant temperature than my hands.

So I will kiss my kids in TWO places: their forehead (of course), and their belly.

I don’t know why it is, but often I get a more “accurate reading” from kissing their tummy than their forehead. But it also depends on which kid it is, because they’re all different.

For example, my oldest child’s forehead rarely feels overly hot, even when he has a moderate to high fever. But during a fever, his belly is like a mini-furnace. And my lips can always tell the difference between a normal warm belly, and a feverishly warm belly with him.

My third child, on the other hand, frequently has a warm head, especially if he has been playing hard. But his tummy will be cooler to the touch, which reassures me that he doesn’t have a fever.

And then both my daughters just turn into mini-furnaces all over, so there’s really no need to give them a “Mama Kiss” at all…other than that we all like it 🙂

Rectal Thermometer (aka Butt)

Rectal thermometers can be kind of scary if you’re not used to using them. And even more so if your child is not used to using them!

But the truth is that a rectal temperature is considered the “gold standard” for measuring body temperature. This is especially true for infants, where it’s particularly important to get an accurate body temperature reading.

In fact, if you’ve ever heard that “It’s not even a fever unless it hits 100.4”, that only refers to rectal temperature. Other methods of measuring body temperature partly rely on “surface” temperatures, and so they’re more likely to be influenced by variables other than fever. That’s why they also usually have a slightly lower benchmark temperature for what constitutes a fever.

But like most things in life, there are definitely a few tricks that you can use to make taking a rectal temperature go a little easier:

  1. Buy a Rectal Thermometer that is only for rectal use (This is the one have used for all my kids, and is still going strong): The benefits of getting a dedicated rectal thermometer are that the tip is perfectly sized so that you don’t have to worry about sticking it in too far, even if your child wiggles and fights! It’s also slightly flexible, which makes it more comfortable when inserting. On another note…there’s nothing worse than accidentally putting a multi-use thermometer in someone’s mouth after having used it in someone’s butt. Even if you clean it first…personally, I just can’t get over that…
  2. Always lubricate before inserting: Even though it’s only being inserted a small way, a little lubrication will help it slide easier. Anything will work…coconut oil, olive oil, or even petroleum jelly if you use that. Just make sure to have a tissue handy to clean off the rectal thermometer when you’re finished.
  3. Your child picks up on your attitude: This is probably the most important tip! If you act nervous and seem to think that it might hurt…then your child is going to assume that you’re the expert and feel afraid, too. And they’ll probably clench their butt cheeks together and fight the whole process, which WILL make it hurt! But if you act confident, explain what you’re doing using simple and clear explanations, and act like this is no big deal (fake it before you make it, but it’s really not a big deal, trust me!), then your child will be much more likely to cooperate without a problem. If you’re really concerned about how your child will respond, then practice doing rectal temperatures before they are sick so that they are already used to it when you really need it.

Oral Thermometer (aka Mouth)

This is probably the most common method used to assess body temperature, but it can be influenced by how recently you ate or drank. And for kids, of course, how well they can hold the thermometer under their tongue!

So first thing’s first…if you use this method, make sure your child can hold it under their tongue! That skill usually develops somewhere around 4-5 years old. Make sure you watch them carefully to make sure it stays (more or less) under their tongue. Feel free to help them hold the thermometer to get the most accurate reading.

Second thing…make sure your little one hasn’t eaten or drunk anything for about 30-minutes, because that can change the surface temperature of the mouth. Depending on whether they consumed something hot or cold, it will either artificially elevate OR decrease their oral temperature. So hide those sippy cups!!

(*Total Grammar Nerd Side Note* I had to google whether to write “drank” or “drunk” in that last paragraph. I finally decided it should be “drunk” because I used the word “hasn’t”, and I think that makes it the past perfect tense. Feel free to comment below and correct me if I’m wrong! *End Grammar Nerd Side Note*)

Now, with all that being said…

Even if you make sure the thermometer stays under the tongue, AND there’s been nothing consumed for 30-minutes, the oral thermometer will still give you a lower temperature reading than a rectal thermometer.

So theoretically, a “fever” as measured by an oral thermometer could be as low as 99.4. That’s one full degree lower than the expected rectal temperature would be. However, the common practice is that an oral temperature is not counted as a true fever unless the it reaches 100 degrees or higher.

(And we still look more at how our kids are behaving to determine how sick they actually are, versus what the thermometer number says.)

BUT it’s also super important to read the instructions for whatever thermometer you buy, because some thermometers already take that difference into consideration when they’re calibrated! If your thermometer does this, then it basically means that approximately 1 degree is automatically added to the actual temperature measured.

If that’s the case with your digital oral thermometer, then the final temperature displayed would (in theory) be more directly comparable to a rectal temperature. But you’ll only know for sure by reading the instructions, so don’t skip them!

I use an oral thermometer like this one…but even though it’s multi-functional, I choose to never use it for rectal temps. That just feels gross to me. But I do occasionally use it to take an armpit temperature, and so I like that it has an auto-setting for that, as well.

Auxiliary (aka Armpit) Temperature

Not taking an Auxiliary Temperature…just applying some auxiliary spray!

This is one of the least reliable ways to measure temperature, but if you have a kid who is too young to do an oral thermometer, and just won’t cooperate with a rectal temperature no matter what you do, and you have no other options available…then it’s always a less invasive way to go!

Just like with your oral temperatures, it’s going to measure a lower temperature than what you would get rectally (unless the manufacturer calibrated your thermometer to take that into account, of course). Normally, anything over 99 degrees auxiliary is considered a fever.

But always make sure to read the instructions.

It’s pretty straightforward to take an armpit temperature: lift the arm, insert thermometer tip into the armpit, then lower the arm so the tip is surrounded. Hold until the thermometer beeps!

This can be a nice option if you want to measure your child’s temperature while they’re resting or sleeping. Many young kids are deep enough sleepers that moving their arm around a little bit wouldn’t wake them…but sticking the thermometer up their butt probably would!

Temporal (aka Forehead) Thermometer

Wen I worked in the pediatric operating room, this is the type of thermometer that the Post-Operative nurses always used to check patients temperatures immediately after surgery.

It’s quick and easy to use. You start by placing the sensor in the middle of the forehead, slide it to the side of the face and down across the temple, then back up to center again.

It works by sensing the temporal artery, which is located (duh) in the temple area. The infrared sensor takes a surface temperature reading across the entire swipe, but then recognizes a temperature spike when it crosses the location of the temporal artery (because of the warm blood within!). The thermometer uses that temperature reading to report the body temperature.

It’s definitely a nice option when you’re worried about your child while they’re sleeping, but don’t want to wake them up. But…

…there are still some cons.

First off, this is a more expensive option compared to standard oral and rectal thermometers. Not extreme, but still in the $40-50 for the least expensive models. That’s approximately 4x what you’ll pay for the less high-tech methods like oral, auxiliary, and rectal.

Secondly, I personally did not have a good experience with mine!

I left the OR to stay home full-time when we had our first child, but fondly remembered how easy it was to take temperatures with the Temporal Thermometers. So when our budget allowed, I purchased the least expensive model I could find.

Unfortunately, I found it to be very inconsistent in reading temperature. Like, I would measure 3 times in a row and get 3 significantly different readings. Or different readings depending on whether I swiped to the right or left side.

Plus, it was kind of difficult for me to swipe smoothly across their sweaty skin. And it made a beeping noise that woke up my kids if I tried to swipe it on them while they were sleeping.


In any case, I almost always ended up taking a Rectal Temperature to double check my inconsistent Temporal Thermometer readings, anyway.

So I finally decided to ditch my Temporal thermometer. But I do still wonder if I would have had a better experience if I had bought a more expensive model. After all, it was accurate enough for Post-Op!

Tympanic Membrane (aka Ear) Thermometer

I’ve never owned a Tympanic Membrane thermometer myself, but I remember my mom using this kind of thermometer on me as a kid.

I remember it being uncomfortable in my ear, sometimes to the point of hurting. Maybe I just had a smaller than average ear canal, I don’t know.

In any case, it works similar to the way a Temporal Thermometer works, but without the need to “swipe”. Instead, you gently pull the ear lobe up and back for kids (this straightens out their ear canal a bit). Then insert the tip of the Ear Thermometer into the ear. The infrared sensor measures the temperature of the ear drum, which is a fairly accurate measurement of internal body temperature.

The good news is that this type of thermometer can be used even if your child has ear tubes, excess ear wax, and even an ear infection (although I imagine that might hurt a little extra!).

The downside is that it may be uncomfortable for your child (if my childhood memories are any indication…), and it’s also on the more expensive side of thermometer options.

The easiest (and most cost-effective) way to get a Tympanic Membrane Thermometer is to purchase one that is also a Temporal Thermometer. That way you get a “2-for-1” at around the $40-$50 price range.

And if you don’t love the temporal thermometer, then at least you have the tympanic membrane option as an alternative!

So which thermometer is best for kids?

You’ve probably figured out by now that I’m more of a Rectal Thermometer fan.

It’s the only method that’s officially recommended for babies under 3-months, and it’s the most accurate and reliable method available for other ages, as well. It’s not as hard (or uncomfortable!) to do as you might think, so long as you have a dedicated rectal thermometer…and a positive attitude 😉

However, it DOES start getting a little weird when you’re still trying to get a rectal temperatures on a 10-year old, sooo…

I also keep a Multi-functional Oral thermometer on-hand for myself, my husband, and my older kids. I never use the rectal setting on this thermometer (and I make sure that my husband never uses it that way on the kids by accident, either…). But I do occasionally use the auxiliary setting, so it’s nice that it’s available.

But the first method I always use for measuring temperature?

It’s always my hand or my Mama Kisses. Because in the end, temperature is just a number. It’s much more important to observes how your child feels, and how they act. Those are the symptoms that will give you more information about how sick they are, and how serious it really is.

Which is good news, because it means we Mamas can stop worrying quite so much about a simple fever.

LEAVE A COMMENT: Which type of thermometer do you prefer to use with your kids?

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4 thoughts on “Best Way to Measure Fever in Kids”

  1. Lol on the drunk note. I would have said make sure your child hasn’t had anything to eat or drink so I wouldn’t have had to figure it out.

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