Hot trends in fever thermometers: Which thermometer is most accurate?

Your baby’s sick. You put your hand on her little head and it feels warm. You think she has fever, but you’re not sure. You need to take her temperature. Where’s that thermometer when you need it?

Looks like you’re taking a trip to the store to purchase one. And now, there are many choices—digital, tympanic, temporal. Which one’s best?

Samuel D. Clark, DO, Pediatrician at the Waco Pediatric Clinic, offers some helpful tips on selecting the right fever thermometer for your child.

“A thermometer’s accuracy depends on how you use it and what age the child is. For children under the age of four, you’ll want to use a rectal thermometer for the most accurate temperature. For older children, an oral thermometer is pretty darn good,” says Dr. Clark.

Here’s an explanation of the various kinds of thermometers available for home use.

Traditional Digital Thermometers (for Oral and Rectal Use)

  • Can be used under the tongue or in the rectum
  • Easy-to-read digital numbers
  • Most accurate, particularly when used rectally
  • Inexpensive

Dr. Clark says, “The gold standard for accuracy is still the rectal thermometer.” Rectal temperature is considered most accurate because it best represents your body’s core temperature and is less influenced by external factors, such as air conditioning or wind.

“If she had a temperature of 99°F or higher, you’d want to double check with a digital thermometer just to be sure.”


Dr. Clark recommends taking your child’s temperature rectally until the age of four or five, when your child can hold an oral thermometer comfortably and correctly in his or her mouth.

To underscore the effectiveness of the rectal thermometer in infants, however, Dr. Clark says: “In kids less than three months of age, the only true thermometer you can rely on is a rectal thermometer.”

Digital Pacifier Thermometer

  • Designed for children three months of age or younger
  • Inaccurate
  • Best used as a screening to tool
  • Inexpensive

“You could use a digital pacifier as a screen to see if your child has a fever, but I wouldn’t use it as your sole source,” says Dr. Clark. “If she had a temperature of 99°F or higher, you’d want to double check with a digital thermometer just to be sure.”

Digital Tympanic Thermometer

  • Quickly takes the temperature in the ear
  • Frequently used in physicians’ clinics and Emergency Rooms
  • Often inaccurate when measuring elevated temperatures
  • Best used as a screening tool
  • Expensive

Dr. Clark says studies show that though digital tympanic thermometers are widely used, their accuracy is questionable. They’re useful in ruling out fever, but if your child has an elevated temperature, the exact degree of fever might be misgauged with this instrument.

Temporal Artery Thermometer

  • Easily takes the temperature across the forehead
  • Sometimes used in physicians’ offices
  • Often inaccurate when measuring elevated temperatures
  • Best used as a screening tool
  • Expensive

Similarly, this thermometer is great for well-child checks, says Dr. Clark, when the presumption is your child doesn’t have fever. But if you’re looking for pinpoint accuracy, studies show this thermometer isn’t reliable.

Years ago, glass mercury thermometers for both oral and rectal use were widely available. But these difficult-to-read thermometers are largely unobtainable now due to safety concerns regarding the volatility of the mercury when broken.

A Thermometer as a Screening Tool

For ease, Dr. Clark suggests using a tympanic or temporal thermometer—or using a traditional digital thermometer under the armpit—to check whether your child has fever.

If your child is running a temperature greater than 99°F on these less accurate instruments, follow up with a rectal thermometer if your child is under age four or five, or use a traditional digital thermometer orally for older children to ensure a more accurate measurement.

Thermometer Care

Traditional digital thermometers are generally the cheapest to purchase and give you the greatest accuracy. Purchase two—you’ll need separate thermometers for oral and rectal use.

Dr. Clark recommends wiping down your thermometer after use with a nontoxic bacteria-killing wipe.

And don’t store it near your toilet “where spores and microbes are flying about,” he recommends. Better to store it in a container in a cupboard.

Dr. Clark also suggests keeping it in the same place each time: “You don’t want to have to search for it when you need it.”

Note: If your child is less than three months old and has a fever of 100.4°F or higher, Dr. Clark recommends that you take your child to the clinic or to the Emergency Room.

Or, for children older than three months—if your child has a sustained fever of 103°F or higher that’s not responding to ibuprofen or acetaminophen, Dr. Clark recommends that you contact your child’s physician.

1 thought on “Hot trends in fever thermometers: Which thermometer is most accurate?”

  1. I already tried most of the thermometers that you mentioned here and sad to say none of them works for me. The best thermometer that I have is the Thermee non-contact forehead thermometer. This kind of thermometer is such a life saver. I love using it and so perfect for my kids.

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Hot trends in fever thermometers: Which thermometer is most accurate?