What is the Best Type of Thermometer for Infants?

A fever in an infant can be the first sign of an illness. While a rise in body temperature above 100.4 degrees Fahrenheit is part of a healthy immune system response, it does signal potential danger and need for further evaluation. Since a reading may lead to a call or visit to the child’s doctor or emergency room, accuracy is key. What is the best type of infant thermometer?

A digital rectal thermometer.

This is according to such authorities as the American Academy of Pediatrics, Consumer Reports, and the American Academy of Family Physicians.

The definition of a fever is important as well. According to the AAFP:

A normal temperature is about 98.6°F (37°C) when taken orally (in your child’s mouth) and 99.6°F (37.5°C) when taken rectally (in your child’s bottom). Many doctors define a fever as an oral temperature above 99.5°F (37.5°C) or a rectal temperature above 100.4°F (38°C).

Fever in infants less than 4 weeks old can be an emergency, and most likely will require the baby to be hospitalized for evaluation and treatment. Fevers in babies 4 weeks to 3 months old are also considered an emergency requiring prompt medical attention. Always call your doctor for advice regarding fever.

The old-fashioned mercury thermometer has been phased out due to potential toxicity if the thermometer breaks and leaks mercury.

Consumer Reports recommends purchasing a rectal thermometer that can also be used orally as the child gets older, perhaps above age 3.

Expensive thermometers are not necessarily any better, but brands such as Omron have passed muster. Consumer Reports also lists BD Digital, Bebe Sounds, Safety 1st, Summer Infant, The First Years, and Vicks.

Be patient. Thermometers advertising instant reads sound great, but a reading in 20-60 seconds is sufficient and perhaps more precise.

Given the greater precison of rectal thermometers, my office has begun an ambitious initiative to check the temperatures of all our adult patients using the rectal technique as well. So far the response has been mixed. Some patients refuse the more painstaking measurements, while others seem to easily dismiss the added indignity as “just more of the same” they’ve come to expect from American healthcare. Just kidding.

But there’s no kidding about rectal thermometers being the best type for infants.
Happy Mother’s Day, and thanks for enduring all the unpleasantries, Mom.


3 thoughts on “What is the Best Type of Thermometer for Infants?

  1. Hal Dall, MD

    Our hospital uses the “temporal thermometers” by default to “save time” and “because patients like them”. I have to order “real temps” or I get the psuedotemps.

    (At one time I had the same struggle over tympanic thermometers).

  2. Bianca Castafiore

    Ewww, you got me. I was just getting ready to make sure you hadn’t opened any Dr. Charles Franchise Locations near Marlinspike Hall when I made it to “just kidding.”

    Don’t mess with the few perquisites of adulthood, Doc.

    P. S. So what gives with ear thermometers? That’s what is in use at my internist’s office these days… Where does “normal” fall in ear measurement terms?

    P.S.S. Please post more often?

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