General Health & Wellness • Jan 31, 2012

Choosing a thermometer

My two year old had a fever the other day and so I went digging under the bathroom sink for a thermometer.  To my surprise, I found eight thermometers, each of a different type.   I’ve been a parent for seven and a half years, and I have four kids.  This means I have bought, on average, more than one thermometer per year and we own two thermometers per kid. 

Thermometers are confusing, even for pediatricians.  So, as a pediatrician and a mom, here’s my run-down on the good, the bad, and the ugly of thermometers.   

  • Digital Thermometers are usually the cheapest option and provide a very accurate body temperature in patients of all ages.  They can be used to measure temperature in the mouth (oral) or under the arm (axillary).  Rarely, your pediatrician may ask you to use a digital thermometer to take a rectal temperature in an infant.  In kids school age and older, it is usually best to use a digital thermometer in the mouth, under the tongue.  In infants and toddlers, it is best to measure temperature under the arm. 

One key tip:  never add or subtract degrees from the measured temperature.  Just report the temperature measured and the method used to measure it.  For example, you might tell your pediatrician, “my baby’s temperature was 100.4 under the arm with a digital thermometer.” 

The problem with digital thermometers is that the cheapest ones take longer to measure temperature.  So, if you have a screaming, ill infant, it can be important to have a thermometer that takes less than 30 seconds.  I also like models that have a back-lit digital display because I find that I am often taking temperatures at night, in the dark, while trying not to wake a sleeping child.  If you’re like me and can’t read the display without your eyeglasses (which you forgot to put on while checking on a child in the middle of the night), I recommend a talking thermometer.  I also like a thermometer with a memory feature, so that I don’t have to write down temperatures in the dark in the middle of the night without my eyeglasses.    The memory feature also comes in handy when you call the pediatrician in the morning and they ask how high the fever was at three am. 

Many low-cost digital thermometers use batteries that are very difficult to find.  You pretty much have to throw the thermometer out when the batteries die, or buy replacement batteries online that can cost almost as much as a new thermometer.  I had this experience with the Vicks SpeedRead digital thermometer.  I went through four thermometers before I quit buying this brand. 

Here is my favorite family thermometer—the MOBI TempTalk, which costs about $10 and is available at Wal-Mart, Amazon, and most retailers. 

  • Electronic Temporal thermometers are pressed or swiped against the forehead, behind the ear, or over the temporal artery on the side of the head.  They usually cost about $35-$65.  Many pediatricians use them in their offices because they take just a few seconds to measure temperature and require little or no cleaning between patients.  They are also easier to use in infants and toddlers because you don’t have to hold their arm down in the way necessary to take an axillary (armpit) temperature with a digital thermometer (as above).  They usually come with all the bells and whistles of a back-lit display and memory like the more expensive digital thermometers.   

The problem with temporal thermometers is that if you take your child’s temperature several times in a row you can get significantly different measurements.  Since they take just a few seconds to work and they don’t aggravate kids, most parents can’t resist the temptation to take several temperature measurements.  All it takes is a slightly squirmy child and you will doubt the accuracy of the reading.  It is important to read the package instructions and follow them closely in order to get accurate measurements.  Most temporal thermometers need a minute or so between measurements.  Also, the method and location of skin temperature measurement varies between models. 

  • Electronic ear thermometers are less popular now that electronic temporal thermometers have come down in price.  Like temporal thermometers, ear thermometers work in just a few seconds.  But many toddlers, including mine, don’t like having things stuck in their ears.  Ear thermometers also require probe covers that need to be replaced with each use.  They are not accurate in young infants with narrow ear canals.  Parents with ear thermometers often cannot resist the urge to check a temperature in each ear, and then feel frustrated when the temperatures are not the same. 
  •  Disposable forehead thermometers are thin pieces of plastic that stick onto a patient’s forehead and change colors to indicate body temperature.  I do not recommend them.  They often give a range of temperature rather than a specific measurement, and I find that they often cause parents to over-estimate temperature.  I have seen many parents rush kids to the ER with temperatures of 105-106 as measured with these forehead thermometers, only to get an ER measurement that is significantly lower.  If you do choose to use this type of thermometer, be sure to closely follow the package instructions regarding how long to leave the thermometer on the skin and how to read the thermometer. 
  •  Pacifier thermometers are shaped like a baby’s pacifier and have a digital display for the temperature. I find they rarely work well and I do not recommend them.  First of all, your baby will not be fooled and will know the difference between this pacifier and his or her favorite.  You will frustrate yourself trying to get your crying, ill baby to suck on this unfamiliar pacifier.  If your baby is asleep, you will have to wake them up and then try to convince them to suck on this unfamiliar pacifier.  They usually take longer to work than other types of thermometers.  Also, pacifier thermometers are useless once your baby outgrows a pacifier.  
  •  Mercury thermometers are no longer considered safe, especially for use in children.  If you still have one left over from when you were a child, you will have to dispose of it at a household hazardous waste collection facility.  Many communities hold hazardous waste collection days.  Contact your local sanitization department or health department for more information. If you break a glass thermometer, call your local poison control center immediately.

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