How to Take a Baby's Temperature

How to Take a Baby's Temperature - Illustration by Jiaqi Zhou

Verywell / Jiaqi Zhou

Taking care of a baby can be overwhelming—especially when they’re not feeling well. Parents often have questions about the proper way to check a baby’s temperature when their forehead is feeling warm. If you've seen different types of thermometers on the market, you may be wondering which is the best choice for you and your baby.

It’s understandable to have questions, and we’re here to give you answers. Let’s take a look at which thermometers work best for babies, how to use them properly, and what to do if you find your baby is running a fever. 

Types of Thermometers

Taking a baby’s temperature is a bit more complex than simply sticking a thermometer under their tongue. Unlike older children, babies cannot hold an oral thermometer in their mouths. How you take your baby’s temperature will depend on their age and your personal preference.

The Importance of Digital Thermometers

The American Academy of Pediatrics (AAP) suggests parents exclusively use digital thermometers to take their child’s temperature. Mercury-containing thermometers are no longer recommended for children under any circumstances.

Mercury Thermometers

These thin, glass devices are filled with silvery metal. They pose a risk because they can break and release toxic levels of mercury fumes.

If you still own a mercury thermometer, the AAP recommends disposing of them immediately and replacing them with a digital thermometer. 

Digital thermometers are also preferable because of their ability to give you a quick, accurate reading. In fact, digital thermometers can reveal your child’s temperature in as little as 10 seconds. You’ll appreciate the swift reading when dealing with a fussy, squirmy baby! 

You can find digital thermometers online, in baby stores and drug stores. They are safer than thermometers containing mercury and are sold at affordable prices. 

Taking Your Baby's Temperature

How you take your baby’s temperature will depend on both your preference and their age. You may use a forehead thermometer (temporal artery) on babies of any age. These no-contact thermometers work by measuring the heat waves coming off your baby’s skin. Each forehead thermometer works slightly differently, so you will want to be sure to read the specific instructions that come with your thermometer before using it. 

For younger babies, a rectal temperature is generally known to give the most accurate reading. You can also check a baby's temperature under their armpit, which is called an axillary temperature. Babies who are older than six months can use an ear (tympanic) thermometer. 

Multi-use digital thermometers can be used for rectal or armpit readings. However, it’s important to reserve specific thermometers for each use due to sanitary reasons.

A multi-use digital thermometer can be used for rectal, armpit, or oral readings. Digital forehand scanners and digital ear thermometers are also easily readily available in stores or online.

Multi-Use Thermometers

Multi-use thermometers work by activating a small sensor at the thermometer's tip that reads your baby’s temperature. If you’re purchasing two multi-use thermometers for axillary and rectal readings, it may be helpful to label them accordingly.

Forehead Thermometers (Temporal Artery)

If you have multiple children, forehead thermometers can come in handy. The temperature is read by pointing the thermometer at the front and side of your baby’s forehead. The fact that forehead thermometers require no contact can help reduce the spread of germs in your household. 

Ear Thermometers (Tympanic)

Ear thermometers read the heat waves in your baby’s eardrum and report the temperature. This type of thermometer is often used in the doctor’s office. Babies under six months of age should not use an ear thermometer. Be sure to read the instructions carefully, as ear thermometers must be placed precisely in the eardrum to generate an accurate reading. 

Which Thermometer Is Most Accurate? 

Sometimes, it takes a bit of trial and error to determine which method is best for taking your baby’s temperature. Some babies tolerate certain thermometers better than others, and it’s important to find the one that works best for you and your baby. Still, parents should be aware some temperature-taking methods produce more accurate readings.

Younger Babies

Generally speaking, the most accurate reading for babies is a rectal temperature. However, some parents have hesitations about taking their baby’s temperature rectally. Forehead temperature readings are next in line to rectal temperatures in terms of accuracy. 

You may notice your child’s doctor performs an axillary reading during well-visits. This method is minimally invasive but is seen as the least accurate method for temperature taking. This method is best used for screening purposes and may be followed up with a rectal temperature if a fever is noted. 

Older Babies

Ear thermometers are more accurate for recording temperatures than axillary readings but are less accurate than rectal or forehead methods. The other downside is they must be performed precisely to produce an accurate reading and are only appropriate for babies who are six months or older.

If you’re seeking a thermometer to add to your baby registry, for example, you should opt for a multi-use digital thermometer over an ear thermometer to start.

How to Use Each Type of Thermometer

It’s useful to familiarize yourself with your thermometer before it becomes necessary to try it out. If your baby isn’t feeling well, you’re likely to feel somewhat flustered, so knowing what to do ahead of time will give you one less worry.

Having another adult with you can be helpful, as babies are squirmy by nature. If that’s not possible, you can certainly accomplish the task on your own.

Before taking your baby’s temperature, be sure you fully understand the instructions. It’s also helpful to gather your supplies beforehand so you can focus. 

Rectal Thermometer

Rectal thermometers can be used on both babies and toddlers. This is a sensitive area, so be sure to insert the thermometer carefully. You’ll also want to take some extra precautions before using a rectal thermometer. 

  1. Place your baby on a flat surface. Lie your baby on their back. If you have a changing table with a strap, you can secure it to keep your baby still and safe. 
  2. Lubricate the thermometer. Applying a lubricant, such as petroleum jelly, will make inserting the thermometer easier. 
  3. Lift your baby’s legs. Gently pull your baby’s legs to their chest to get better access to the buttocks area. 
  4. Gently insert the thermometer into your child’s anus, about ½ an inch to 1 inch. Place the thermometer in your baby’s anus. The thermometer should be inserted about ½ an inch to an inch and should never be forced. 
  5. Wait for the thermometer to beep. The thermometer will beep when your baby’s temperature has been recorded. 
  6. Clean the area. Use a baby wipe to clean your baby’s diaper area. You may notice your baby has a bowel movement after the thermometer is removed, which is perfectly normal. 
  7. Disinfect the thermometer. You should clean the thermometer with soap and water or an alcohol swab after each use. 

Ear Thermometer

  1. Position the thermometer in your baby’s ear. Ear thermometers give accurate readings only when properly placed. 
  2. Aim the tip according to the instructions. You will typically want to position the tip of the thermometer between the opposite ear and eye.
  3. Be mindful of the elements. To ensure an accurate reading, you’ll want to be sure your baby has been in the same environment for at least 15 minutes. Wait a bit before taking your baby’s temperature if they’ve recently been outdoors. 

Forehead Thermometer

  1. Review the instructions. Forehead thermometers are relatively simple to use, but each model works a bit differently. Brush up on where to place the thermometer and how to record an accurate reading before use.
  2. Aim the thermometer at your baby’s forehead. Depending on the thermometer, you may point it at your just baby’s forehead, or the forehead and temple area. 
  3. Wait for the beep. You will see the recorded temperature on the screen after the thermometer beeps. 

Treating Your Baby’s Fever

Everyone has their own unique baseline temperature, so what is considered a fever varies somewhat from person to person.   

According to the Academy of American Pediatrics (AAP), a baby’s temperature is generally considered a fever when it rises above 100.4 degrees Fahrenheit (38 degrees Celsius). Fevers in babies under three months can be serious and should be immediately reported to your pediatrician.

Fevers above 104 degrees Fahrenheit (40 degrees Celsius) are considered a medical emergency. If your baby’s fever reaches or exceeds this temperature, you should take them to the emergency room for a medical examination.

Babies can also overheat easily—even if they are not ill. Exposure to excessive heat can raise your baby’s body temperature. Lethargy, labored breathing, or confusion may be signs your baby is suffering from heatstroke. Babies who show signs of heatstroke should be cooled down, hydrated, and evaluated by a medical professional.

A Word From Verywell

Your baby’s first fever can be a worrying time, but you’ll be best prepared by familiarizing yourself with thermometer options and temperature-taking instructions.

In most cases, you’ll be surprised at how simple today’s thermometers are to use. There are many options available, so you’re sure to find a thermometer that works well for both you and your baby.

Remember, your pediatrician is available to give you advice about your child. Feel free to bring up any questions you have about appropriate thermometer usage at your baby’s next appointment. This will help you feel more confident about treating your baby if they develop a fever.

1 Source
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  1. Healthy Children. How to Take Your Child’s Temperature.

By Renee Plant
Renee Plant is a health and wellness freelance writer with a passion for delivering well-researched, factual content to readers.