Saturday, March 27, 2010

How do I take my child's temperature?

I am always surprised by the amount of people who don't know how to do this.

There are a multitude of thermometers available that go in pretty much every orafice of the body. Most of them are not very accurate but you can use them to get a rough idea of a fever. When you tell your health care provider about a fever it's important to let them know how you measured the temperature.

Oral thermometers are the standard for older children and adults. They are acccurate and reliable. There are many types available. I recommend a digital thermometer that registers a reading quickly so you don't have to deal with a squirming child with a thermometer in their mouth. My twins are starting to be able to keep a thermometer under their tongues but it is difficult for them to hold it there for a long time. (My son actually lifts his tongue up with his fingers to put the thermometer in his mouth.. I don't get that one but whatever.) Normal oral temperature is about 98.6 F or 37 C but this can vary. A fever is considered anything over 100.4 F. Oral temperature can be affected by hot and cold drinks.

Axillary (under the arm) measurements are good for babies and young children and anyone who can't tolerate a thermometer under the mouth. To take an axillary temperature, just place the thermometer into the armpit and hold it tightly until the temperature registers. Make sure the tip of the thermometer is in the axilla (armpit) and not sticking out the back. There is a common belief that you should add a degree to an axillary temperature. This isn't necessary- just let your health care provider know you took an axillary temperature.

People are often afraid of rectal temperatures. This is the most accurate way to get a temperature in a small baby. (It's also a good way to get your baby to poop!)

Taking a rectal temperature isn't as scary as it sounds...

1. The first thing you need is a rectal thermometer. Make sure you don't use the same thermometer in the mouth!
2. Put a small amount of lubricant such as vaseline on the end of the thermometer.
3. Lay your baby on his back with his legs up or on his tummy on your lap.
4. Spread your baby's buttocks apart and slide the thermometer into the rectum. Put it in until you feel resistance, which should be about 1 inch. Most rectal thermometers have a different color or some marking to make it obvious how far it should go in.
5. Turn it on and wait until the temperature registers.

When you are done, make sure you clean the thermometer!

Tympanic thermometers are notorious for being inaccurate. I use one in my house but it's really only to get a rough idea of whether or not they have a fever. The most important thing about taking a tympanic temperature is to make sure you pull the outer part of the ear up and back before inserting the thermometer. This will straighten the ear canal and allow the probe to get all the way into the ear. When you put the probe in, make sure you feel it go into the ear canal.

There are also temporal artery thermometers but just avoid them. They don't work.


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  1. Laura, what is your opinion of the thermometers that you slide across the forehead to the ear? (I don't know what those are called.) Are those accurate enough for toddlers? We purchased one because that was what our pediatrican was using. We have a toddler who is proned to get febrile seizures, so it's important to us to be able to recognize fever and treat it aggressively early. Thanks!

  2. They are called temporal artery thermometers. We stopped using them in the ED and went back to axillary and rectal thermometers because they aren't accurate. They're probably good enough to get a rough idea but I've seen them say a kid had a normal temp when they clearly didn't.