Baby Fever? Taking Baby's Temperature

Mother checking thermometer holding her ill baby at homeWhen your baby is sick, it’s important to call your pediatrician with an accurate temperature reading. But, with so many options, how can you choose? To make things easier, we’ve put together a list of the basic thermometer types, and how to use them correctly.


The most accurate way to take baby’s temperature is rectally; in fact, it’s really the only option for wiggly babies under 3 months. The good news is that getting a rectal temp isn’t a big deal for your little one, because it’s not that different from lying on a table for a diaper change. Select your thermometer and place a small amount of water-soluble lubricant (Vaseline) on the tip, or use covers. Ideally, use a thermometer labeled for rectal use, so it can’t be inserted too far. If you have a multi-use thermometer, insert it no more than three-quarters of an inch, keeping two fingers on it and your hand cupping baby’s bottom.

Extra tip: Don’t be surprised if she poops right after!

Extra extra tip: Clean it really well, and label it for rectal use only!


Ah, the tried-and-true method your own mother used—only now, it’s digital. These are best for children age 4 and up, because babies just aren’t able to sit still and keep the thermometer in place. Remember not to take an oral temperature after feedings.


The infrared thermometers can be pricey, but they’re very accurate if used correctly, even on infants. The trick is to keep the end flat against baby’s forehead, press the button, and swipe across in a straight line. Don’t let go of the button until the thermometer is off baby’s skin. These thermometers can be more sensitive to air or skin temperature (rather than the temporal artery they’re supposed to target), so make sure the room isn’t too hot or too cool, and that baby hasn’t just taken a warm bath.

Axillary (under the arm)

The cheap digital thermometers work as well as anything for reading baby’s axillary temperature. The problem is that this is one of the least accurate methods, and readings may be one half to one degree lower than baby’s true temp. If you do go this route, make sure the thermometer is only touching skin, not clothing, and hold it in place until it beeps. Be sure and tell the doctor or nurse that the reading was recorded under the arm.


Using the same principle as the forehead thermometers, this one is inserted slightly into the ear canal to bounce infrared light off the eardrum. Accuracy can be very good, but there are too many variables to rely on it. Younger children may have such narrow ear canals that the beam can’t get through, or the ears may be too clogged with wax.

Other types of thermometers that may seem convenient are generally not recommended, such as the stickers that go on baby’s forehead, and the pacifier-type thermometer. These are just too inaccurate. When in doubt, ask your pediatrician what they recommend.