Fever can be a sign of many viruses, but it is especially important to watch for with COVID-19.
An easy way to determine if you are developing a fever is to compare your current body temperature to your average body temperature.
Everyone has a unique average body temperature, but when someone’s temperature is higher or lower than their average, it can be a sign of illness. The best way to find someone’s average temperature is to measure it once in the morning and once in the evening for a few days when healthy. This will give an idea of the person’s average body temperature. It is important, though, to measure body temperature both in the morning and evening because the body warms up by about one degree throughout the day.
Digital thermometers are recommended of taking a person’s temperature, as they are the most accurate. There are three different types of digital thermometers:
The use of glass thermometers is not recommended. Glass thermometers contain mercury which is extremely dangerous if inhaled or if liquid mercury touches the skin. The potential for the glass to break also poses a health hazard. Plastic strip thermometers are not recommended as they only measure the temperature of the skin, and pacifier thermometers are also not recommended as they are not as accurate as digital thermometers.
When you are taking your temperature orally, it is important that you not eat or drink anything for 20 minutes before you take your temperature.
Wash your hands with soap and water for at least 20 seconds.
Rinse the thermometer off with cold water, wipe down with alcohol and allow it to dry, finally rinse off again to remove alcohol.
Place the thermometer under the tongue, just to one side of the center, and close your lips tightly around it.
Hold the thermometer under the tongue for at least 40 seconds or until the thermometer beeps to finish the session.
Remove the thermometer and wait for the digital numbers to finish blinking. A second beep may announce that the reading is ready.
After reading the temperature, clean the thermometer below the screen with soap and water. Dry thoroughly.
Rinse the thermometer off with cold water, wipe down with alcohol and rinse off again to remove alcohol.
If possible, use a disposable thermometer cover each time and throw it away after each use.
Apply lubricant, like petroleum jelly, to the end of the thermometer to make insertion easier.
Lay the child on their stomach either across your lap or on a bed in a quiet area.
Spread the child’s buttocks with one hand while using the other hand to insert the thermometer about half an inch, gently.
Hold the thermometer in place for at least 40 seconds or until the thermometer beeps to finish the session.
Never use the same thermometer for both oral and rectal temperature checks.
Rinse the thermometer off with cold water, wipe down with alcohol, and rinse off again to remove alcohol.
Place the head of the thermometer in the center of the armpit.
Press the arm against the body, holding the thermometer in place for at least 40 seconds or until the thermometer alerts you that the reading is complete.
Remove the thermometer and read it. Axillary (armpit) temperatures may be one degree Fahrenheit lower than an oral temperature reading.
Remove the cap from the head of the thermometer, which may be shaped like a cup.
Turn the thermometer on.
Place the head of the thermometer against the skin on the middle of the forehead. Make sure there is nothing between the head of the thermometer and the skin.
Press the button to begin taking a temperature reading.
Slide thermometer across the skin to one side slowly, but not up or down, to the side of the forehead next to the eye (temple).
Wait for a beep or the sound made by your thermometer that indicates the reading is ready. Some temporal thermometers beep continuously while it moves across the forehead. For those brands, it is done when it stops beeping.
Remove the thermometer from the forehead and read the temperature.
Clean the head of the thermometer with an alcohol pad or wipe and replace the covering of the thermometer.
Temperature readings may be incorrectly low if you were just in a very cold area right before checking the temperature.
Remove the cap on the probe of the thermometer and check that it is free debris or dirt. Wipe down with a clean cloth or alcohol wipe if necessary.
If needed, place a clean probe cover on the thermometer. A new probe cover should be used every time and used probe covers should be thrown away.
Turn on the thermometer.
To place the probe correctly in the ear of babies 12 months and younger, pull the earlobe back and down gently to ensure correct placement. For children and adults over a year old, pull the earlobe back gently to ensure correct placement.
Insert the probe into the center of the ear canal and press in gently, but do not force.
Press the on button to display the temperature reading.
Remove the probe and discard the used probe cover.
This information has been reviewed and approved by Carrie Horn, MD (April 2020)
The information on our website is medically reviewed and accurate at the time of publication. Due to the changing nature of the COVID-19 pandemic, information may have since changed. CDC.gov and your state’s health department may offer additional guidance.