Children's Health Featured

How to Use a Thermometer

Mom taking son's temperature with thermometer

When you feel sick, one of the first things you might do is get a thermometer and take your temperature. With an accurate reading, you’ll know if you have a fever and if your body is fighting infection. But accurate readings don’t happen by accident. You have to know how to use your thermometer.

Thermometer Preparation

Temperatures are often taken with urgency. However, here are some things you should do before taking your temperature:

Proper Thermometer Use

  • Clean the thermometer. Scrub the thermometer before and after every use with soap and cool water. This prevents old germs from causing new problems.
  • Cool down. Expect an inaccurate reading if you just finished exercising, smoking, taking a hot shower or bath, or eating or drinking hot food.  
  • Know your baseline. Most people have a normal body temperature of approximately 98.6˚F. Yours may be different. Take your temperature a few times when you feel healthy to determine your normal temperature.

A temperature that is a degree above normal (or 100.4˚F or higher) is considered a fever. Avoid using a mercury-based thermometer and choose a safer one, such as a digital thermometer, which is also easy to use.

When using a thermometer, keep the following guidelines in mind.

  • An oral temperature reading takes about three minutes. Place the thermometer under your tongue, close your mouth and breathe through your nose. A healthy temperature taken this way is closest to the 98.6˚F average.
  • An underarm temperature reading takes about five minutes. Insert the thermometer in your armpit and hold your arm close against your body. Temperatures taken this way can be as much as 1˚F lower than an oral temperature.
  • A rectal temperature reading takes about three minutes. Used primarily in infants, this technique results in a temperature as much as 1˚F higher than an oral temperature. Apply petroleum jelly to the end of the thermometer and insert no more than one inch into the child’s anus. Do not push the thermometer past any resistance.
  • A plastic strip forehead thermometer is less accurate than others, but the electronic forehead thermometer is more accurate if the thermometer is properly used. Carefully follow provided instructions.
  • Ear thermometers work fast, but may not be as accurate as other options. With a clean probe on the thermometer, gently pull your child’s ear up and back. Slowly insert the thermometer into the ear canal. Once the canal is sealed off, push and hold the thermometer’s button for one second, and then remove the thermometer.

If you have a fever, a primary care provider at Augusta University Health can help you feel better.

About the author

Children's Hospital of Georgia

Children's Hospital of Georgia

Children’s Hospital of Georgia is the only facility in the area dedicated exclusively to children. It staffs the largest team of pediatric specialists in the region who deliver out- and in- patient care for everything from common childhood illnesses to life-threatening conditions like heart disorders, cancer and neurological diseases.

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