Baby Fever: How to Take Your Baby’s Temperature

No parent likes to see their little one dealing with a cold or a virus. And along with a stuffy nose, a cough or an extra dose of cranky, there’s unfortunately one other reality that often comes along with a sick baby: a fever.

Although they’re not ideal, fevers are pretty common when it comes to all things baby + toddler, and there’s a good chance that as a new parent you’ll be dealing with one eventually. Learning how to take your baby’s temperature safely and accurately—as well as what’s normal and when it may be time to call the doctor—can help you feel a little less panicked the next time the thermometer starts creeping up.

In this article:

• Baby Fever Basics
• How to Take Baby’s Temperature
• When to Call the Doctor
• Shop This Article

Note: This content was reviewed for medical accuracy by Dr. Lisa Di Enno, Board-Certified General Pediatrician and Chief Medical Officer of XpertCare.

Baby Fever Basics

What’s normal when it comes to babies and fevers? And what’s not? Learning a little about the why behind fevers goes a long way.

Why do babies get fevers?

Fevers are associated with lots of different illnesses, both common and more severe, from colds and croup to pneumonia and ear infections. A fever itself isn’t an illness—it’s actually a symptom of one. It’s the body’s way of fighting off infection, kicking off things like the production of more white blood cells to increase the body’s bacteria-fighting powers.

What is a normal baby temperature?

Just like your body, your baby’s body temperature will fluctuate depending on activity or time of day. According to the American Academy of Pediatrics (AAP), a normal temperature for a child ranges from 97 degrees Fahrenheit to 100.4 degrees.

Baby Thermometers 101

If your baby feels warmer than usual or isn’t acting themselves, it’s probably time to break out the thermometer.

What types of baby thermometers are there?

There are three basic types of thermometers available:

• Digital thermometers. These take a minute or less to record a temperature. Some can be held under the tongue, but many are multi-use and can be used orally, under the armpit or in the rectum. (Just be sure to give them a good cleaning after every use!)
• Ear thermometers. Also called tympanic thermometers, these measure temperature inside your little one’s ear.
• Forehead thermometers. These types of thermometers, officially called temporal artery thermometers, are swiped across the forehead to read the temperature of a major vein that’s located there.

What type of baby thermometer is best?

Your little one’s age determines which type of thermometer you should use.

For younger babies, especially those under six months of age, rectal thermometers are the gold standard. A rectal temperature is the most accurate and the one you’ll want to rely on until your child is about three years old.

Here’s the breakdown by age:

• Birth to three months. Use a digital thermometer to take a rectal temperature.
• Three months to four years. Use a digital thermometer to take a rectal or armpit temperature, or use an ear (tympanic) or forehead (tympanic) thermometer.
• Four years and up. Use a digital thermometer orally (if your little one can hold it still), digital armpit, ear or forehead thermometer.

How Do You Take Baby’s Temperature?

You’ll need to follow a different set of instructions depending on how you’re taking your little one’s temperature. Be sure to read the directions that come with whatever thermometer you’re using to ensure you’re operating it correctly.

Rectal temperature:

• Clean the end of the thermometer with soap and lukewarm water or alcohol, then rinse it with cool water and dry.
• Dab a tiny bit of lubricant, like petroleum jelly, on the tip.
• Place your little one on their belly (make sure you’re on a firm surface, like a changing pad or across your lap) and hold them down lightly but firmly by putting your palm lightly against their lower back. If this isn’t comfortable, you can also place your child face up and bend their legs to their chest and rest your free hand against the back of their thighs.
• Use your free hand to turn the thermometer on and insert it into the anus—no more than about 1 inch. Hold the thermometer lightly with your fingers to keep it in place by keeping your hand cupped around your child’s bottom.
• Listen for the beep, and then remove.
• Always be sure to re-clean the thermometer after each use.

Underarm temperature:

• Clean the end of the thermometer with soap and lukewarm water or alcohol, then rinse it with cool water and dry.
• Turn on the thermometer and place it under your child’s bare armpit. Always make sure it’s touching skin, not clothing.
• Gently hold your child’s arm in place until you hear a beep.

Ear temperature:

• Clean the end of the thermometer with soap and lukewarm water or alcohol, then rinse it with cool water and dry.
• Place a clean cover over the end of the thermometer.
• Pull your little one’s ear back slightly and gently place the thermometer in the ear canal. Aim the probe toward your little one’s eye on the opposite side of their head. (Keep in mind that getting the angle right here for an accurate reading can be tough—that’s why using an ear thermometer isn’t recommended for infants and younger babies.)
• Turn on the thermometer and wait for the beep, then remove.

Oral temperature:

• Always wait 15 minutes after your little one has been eating or drinking before taking their temperature.
• Clean the end of the thermometer with soap and lukewarm water or alcohol, then rinse it with cool water and dry.
• Turn on the thermometer and place the tip under your child’s tongue toward the back of their mouth. Hold it in place until you hear a beep.

When To Call the Doctor

A fever is often a good sign that your little one’s body is fighting their infection, but there are a few things to look for if you’re trying to assess whether or not to call the doctor.

“When we talk about a fever ‘coming down’ with Tylenol or Motrin, we only expect to see the temperature go down by about a degree,” Dr. Lisa Di Enno, Board-Certified General Pediatrician and Chief Medical Officer of XpertCare, tells Babylist. “Parents often think the temp should go back to 98.6F, resulting in lots of worried visits to the ER in the middle of the night.”