How to Use a Thermometer to Check for Fever

Know how to use a thermometer correctly. Melissa Ross/Moment/Getty Images

If you think you or your child may have a fever, you need to check your temperature. If you do need to call the doctor, he will need to know how high your fever is. So, be sure you know how to check it the right way. After all, there are several different types of thermometers and it is easier to get it wrong than you may think.

Types of Thermometers

  • Oral - digital or manual
  • Rectal - digital or manual
  • Axillary - digital or manual
  • Tympanic - digital, takes temperature in the ear
  • Temporal - digital, takes temperature on forehead

Checking the Temperature

If you are using a manual or mercury thermometer, you must shake it down so that the mercury level is at least below 96 degrees F.

If you are using a digital thermometer, simply press the button to turn it on.

  • Oral - Place under the tongue; Wait until the digital thermometer beeps or approximately 5 minutes for a manual thermometer; Remember not to take an oral temperature right after eating or drinking something because it will alter the results. It's also important to keep your mouth closed the entire time.
  • Axillary - Place under the arm with the tip in the deepest crease; Wait until the digital thermometer beeps or approximately 5 minutes for a manual thermometer.
  • Rectal - Use lubrication, such as petroleum jelly and place tip in the rectum (opening in the bottom); Wait until the digital thermometer beeps or approximately 5 minutes for a manual thermometer; This method should be used for infants or those whose temperature cannot be taken any other way.
  • Tympanic - Pull the top of earlobe up and back, place tip (covered with probe cover) in ear canal opening, press button until it beeps; Be sure you are pointing the probe into the ear canal opening and not at the wall of the ear, this can result in incorrect results. Tympanic thermometers can be difficult to use on babies and are often inaccurate because their ear canals are so small. 
  • Temporal - Press button down and sweep probe across forehead; This is fairly new technology but seems to be relatively accurate and very quick and easy to use. Be sure to read the instructions for your device - some require a swipe across the forehead and on the neck below the ear. 

Do you need a thermometer? Can't decide which kind to get? Check your options.

  • Digital oral, axillary or rectal.
    Digital thermometers are a great option. They are very inexpensive and much quicker and easier to use than manual mercury thermometers.
  • Tympanic ear thermometer.
    These are very popular, especially among parents of small children. They are faster than regular digital thermometers and are easy to use. You should be careful to use it correctly and know that the results may not be accurate if the child has an ear infection.
  • Temporal scan thermometer.
    The newest and most expensive thermometer on the market. These are the quickest (they only take 1-2 seconds) and probably the easiest to use. In my experience, they have been very accurate, but some people find they read too low at times.

    Now that you know how to take an accurate temperature, you will be ready next time you or your child has a fever.

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