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When your baby has a warm forehead or neck, you know it’s time to take their temperature. But how can you make sure you get the most accurate reading?
Below, we’ll go over what type of thermometer you should use when your baby is showing signs of a fever and how to take their temperature with it.
The best baby thermometer by age: Here’s a quick guide
It may surprise you, but the best thermometer to use and the best method for taking your baby’s temperature depends on their age. The best way to take your baby’s temperature changes at about 6 months old.
The best thermometer for newborns to 6 months old
A digital thermometer that can be used rectally is the best. That’s because the most accurate temperature readings come from direct contact with your baby, which is why you should always use a digital thermometer that can be used rectally for the first 6 months.
You may find an all-in-one thermometer that states it can be used orally, rectally or in their armpit. However, if you opt for an all-in-one thermometer for rectal use, make sure to label it. The same thermometer should never be used for both rectal and oral temperatures.
The best thermometer for infants 6 months old or older
When your baby reaches 6 months old, you now have new (and easier) options. Now, you can use a digital thermometer under your baby’s arm, a remote forehead monitor or a remote in-ear thermometer.
Thermometers to avoid
Thermometers not recommended for a baby at any age include plastic strip thermometers, pacifier thermometers and smartphone temperature apps because they don’t provide accurate readings.
How to take your baby’s temperature rectally
A rectal temperature is considered the gold standard for accurately knowing an infant’s temp until they’re over 6 months old. Here’s how to get an accurate reading.
Using a digital thermometer to measure rectal temperature
Clean the digital thermometer by washing it with soap and water, or wiping with rubbing alcohol.
Lay your baby down either on their back or belly with legs bent toward their chest.
Apply petroleum jelly to the metal tip of the thermometer and gently glide it into the rectal opening – usually about half an inch, but follow your specific thermometer’s instructions carefully.
Turn on the thermometer.
Hold the thermometer in place until it beeps, which is usually about two minutes.
Remove the thermometer.
Make note of the temperature.
Clean the thermometer before storing.
If you’re uncomfortable taking your baby’s temperature rectally, you can call a nurse line and they will walk you through the process over the phone (both your clinic and health plan likely offer this kind of service).
If you’re a HealthPartners patient or plan member, our 24-hour nurse line is there to offer support and advice when you need answers fast or your clinic is closed. Just call 800-551-0859. You can also call our 24/7 BabyLine for questions and advice on new baby care at 612-333-2229.
How to take your baby’s temperature under their arm
Taking your baby’s temperature under their arm is very simple. Just know that this type of reading is less accurate and can be affected by the amount of clothing your baby is wearing, as well as the temperature in the room.
Using a digital thermometer to measure armpit temperature
Remove baby’s clothes so their chest is bare.
Place the digital thermometer in one of their armpits.
Fold their arm over the thermometer.
Turn on the thermometer.
Hold their arm in place until the thermometer beeps, which usually happens in less than two minutes.
Remove the thermometer.
Make note of the temperature, adding one degree to the reading.
How to take your baby’s temperature with a remote forehead thermometer
If your baby is older than 6 months, a temporal artery thermometer (TAT) can be an easy way to measure your baby’s forehead temperature.
A TAT uses infrared light to read the temperature of the temporal artery, which is located in your baby’s forehead.
The benefit of a TAT is that it can quickly record a temperature, and your little one won’t need to hold still for a whole minute or two. But readings can be less accurate than digital thermometers.
Using a temporal artery thermometer
Make sure your baby’s forehead is clean and dry.
Hold thermometer in front of the baby’s forehead at the correct distance. (This distance is different for every thermometer, so make sure to follow the directions for your specific model.)
Hold down the button and wait for the thermometer to beep. This should only take a few seconds.
Make note of the temperature.
How to take baby’s temperature with a remote in-ear thermometer
Another option for babies 6 months and older is an in-ear thermometer. Also called a tympanic thermometer, this type of thermometer measures the temperature of the ear drum using infrared light.
A tympanic thermometer is similar to a TAT but has a small cone-shaped probe to use in the ear canal. Some TATs have probe attachments that allow them to be used in the ear.
Using a tympanic thermometer
Check the inside of baby’s ear to make sure it’s clean.
Clean the tip of the probe with rubbing alcohol.
Gently tug your baby’s ear straight back to make room for the probe.
Gently ease the probe into the ear canal.
Press the button and hold the thermometer in place until it flashes or beeps. This is usually just a second or two.
Remove thermometer.
Take note of the temperature.
If used correctly, in-ear thermometers can provide reliable temperature readings in older babies. But they aren’t as accurate if your baby has earwax buildup or a small, curved ear canal.
Now that you’ve taken their temperature, here’s what you should do next
Does your baby have a temperature? The good news is that most fevers can be monitored and treated at home. But it depends on how old your child is and how high their fever is.
Get tips for treating a fever at home and when it may be time to see a doctor.
