Expert Advice -- Are Ear Thermometers Accurate?

My daughter is 20 months old. Are tympanic thermometers accurate? I seem to be getting a wide range of readings.


Robert Steele

Robert W. Steele, MD, is a board certified pediatrician at St. John's Regional Health Center in Springfield, MO. He graduated from medical... Read more

The tympanic thermometer also called the ear or aural thermometer is a relatively new device for taking a person's temperature. The reading is made by measuring the heat through infrared light. This is convenient because one only has to put the device in the ear, push the button, and check the display for a virtual instantaneous reading. However, there are a couple of drawbacks to this new technology:

• Decisions about which child needs extensive evaluation are often made based upon a very specific temperature. This is especially true for infants under two months of age. The standards for this historically have been done using a rectal temperature with a glass-mercury thermometer. Unfortunately, despite what the ear thermometer manufacturers may claim, the ear thermometer temperature may vary as much as 0.5 degrees Fahrenheit as compared with a rectal temperature. This may not seem like much of a difference, but in an infant under two months of age, it may mean the difference between a spinal tap and hospitalization or not.

• Because the technology is so new, it is not well known what specific things may interfere with a good reading: Does extensive ear wax change the reading? One study says it might falsely lower it. Does an ear infection change the reading? No one is really sure, but one study showed it probably doesn't. Could an ear thermometer actually diagnose an ear infection? Again, not well studied, but what has been done shows it probably couldn't. Does the age of the child make a difference? Here, evidence shows that the younger the child, the less accurate the reading as compared to a rectal temp. from a glass-thermometer.

Your wide range of readings may be due to a number of things ranging from the inaccuracy all testing devices have to the technique in which you are using the ear thermometer. Ultimately, the actual temperature may not make a difference. If your 20 month old has a temperature of 101.2 or 101.7, and you are not sure which it is, it may not matter. They are both fevers. And some toddlers feel just awful with a temperature of 101 while another may be running around playing with a temp. of 102.5. I think the ear thermometers are a great thing and are often very useful but I suggest that the they be used as a screen. If you are not confident about the reading, and you or your doctor feel it is important to get a very accurate reading, check it by taking the temperature the old fashioned way -- with a rectal thermometer.

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