How To Take Your Baby's Temperature

New parents can get rattled when their infant feels warm to the touch and may have a fever, especially if it’s the baby’s first one. The first step for these first-time parents is to take the child’s temperature.

Taking your child’s temperature sounds simple enough, but questions may arise as to the best way to go about getting a safe and accurate reading.

• Which type of thermometer is best?
• Where should the thermometer be placed?
• What is a normal temperature and what is considered a fever?

Fever can be a scary symptom, especially if the baby is only a few weeks old. A fever itself isn’t an illness but a symptom of one. Parents should know that all kids get a fever from time to time. Typically, it’s a sign that the child’s body is fighting infection. In many cases, a modest fever can be safely managed at home. But a high fever can be a sign of a problem that needs to be taken up with the baby’s doctor, especially if you’re dealing with a newborn.

This makes the thermometer one of the most important items in the baby’s first aid kit. Knowing how to get a good temperature reading can help get the little one on the road to recovery.

Thermometer types

The American Academy of Pediatrics (AAP) recommends only using digital thermometers to take a child’s temperature. The old mercury thermometers that our parents used when we were children have been phased out. These glass devices should not be used because they can break and release toxic levels of mercury fumes. You certainly don’t need that added to an already stressful situation.

The digital thermometer is the way to go. They use electronic heat sensors to record body temperature. There are different types of digital thermometers. The best type — or the best place to insert the thermometer, in some cases — depends on the child's age.

Multi-use thermometer

These thermometers can be used to take a baby’s temperature via the rectum, mouth or under the arm. For infants three months are younger, rectal readings are the most accurate and can be easiest to take.

Rectal

• To take a rectal temperature, lay the baby on their belly or on their back with legs bent toward the chest. Apply petroleum jelly around the bulb of the thermometer and insert it gently into the rectum about one-half to one inch or until the tip of the thermometer is fully in the rectum. Stop if you feel any resistance.
• Hold it in place until you hear the beep the gently remove and read the temperature. Never leave a baby unattended with a rectal thermometer inserted.
• Perhaps an obvious point, but never use a thermometer that has been inserted in the rectum for oral readings. Label the rectal thermometer so it is not accidentally used for both.

Oral

• To take the temperature orally, place the tip of the thermometer under the tongue toward the back of the mouth and ask the child to keep his or her lips closed. Remove the thermometer when it indicates that it's done and read the number. If the child has been eating or drinking, wait 15 minutes to take his or her temperature by mouth.

Under the armpit

• When you take the child’s temperature under the armpit, make sure it touches skin — not clothing. While the thermometer is in place, hug the child, keeping the side holding the device against your body. Make sure the thermometer is tightly in place under the child’s arm until you hear the signal indicating it’s done. Remove the thermometer and read the number. Disclaimer: Many doctors consider this method less accurate than rectal readings.

Regardless of where you take your child’s temperature, all thermometers should be disinfected before and after use with disinfecting soap and water or disinfecting alcohol swab.

Digital ear thermometer

These tympanic thermometers use an infrared scanner to gauge temperature inside the ear canal. They can be used on children more than six months old, but they are not reliable for younger babies, because their ear canals are too narrow. Earwax can interfere with the accuracy of an ear thermometer reading, and this type of thermometer needs to be placed correctly in child’s ear to provide an accurate reading. Being outdoors on a cold day may cause a low reading. Wait 15 minutes after coming indoors to take the temperature.

How to use a digital ear thermometer

To get an accurate reading, pull the top of the earlobe up and back. This will help straighten the ear canal and make a clear path inside the ear to the ear drum. Gently insert the tip of the thermometer into the ear canal toward the eardrum until the ear canal is fully sealed off. Once the thermometer is in position, turn it on and wait for it to signal that the reading is complete. Remove the thermometer and read the temperature.

It’s important to note that the AAP advises against using this method for infants younger than 3 months. While a tympanic thermometer provides speedy results, it needs to be inserted at the right angle in a child’s ear to provide an accurate reading. Don’t use these devices right after a child has been swimming or bathing of if ear pain is present.

Temporal artery thermometers

These thermometers use an infrared scanner to measure the temporal artery in the forehead. It can be used even when a child is asleep. Disclaimer: Many doctors also consider this method less accurate than rectal or oral thermometers.

How to use a temporal artery thermometer

Place the thermometer sensor in the middle the baby’s forehead. Press and hold the scan button. Slowly move the thermometer across the forehead toward the top of the baby's ear. Make sure it always touches the skin. Stop at the hairline and release the scan button. Remove the thermometer and read the temperature.

Thermometers we do not recommend

• Digital pacifier thermometers
• Fever strips
• Smartphone apps

Remember, the best method to measure your baby’s body temperature depends largely on the child’s age. And it’s important that the measurement is accurate. Learn more about how to navigate your baby’s first fever here. If your child’s fever does not get better, please contact your pediatrician. If you suspect an emergency, please bring your child to the emergency room.