How to Properly Disinfect a Thermometer

Written by
Mary Marlowe Leverette
Mary has been writing professionally for more than 20 years and is a leading expert on fabric care and housekeeping.
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Mary Marlowe Leverette
Updated 10/15/20
Man's hand holding a digital thermometer

 Grace Cary/ Moment/ Getty Images

Overview
  • Working Time: 5 mins
  • Total Time: 15 mins
  • Skill Level: Beginner

Every home should have at least one thermometer in the medicine cabinet. It's one of the first tools that most of us use when someone doesn't feel well. Monitoring a person's temperature is a good indicator of their well-being during flu season or any bout with illness. You can purchase oral, rectal, ear (tympanic), or forehead (temporal) thermometers.

How Often to Disinfect a Thermometer

Whether you have a mercury-filled, digital, or infrared thermometer, it is essential to disinfect it between uses and, most importantly, if shared between family members. A quick rinse under cold water won't kill the bacteria that can spread to others. However, with just a few minutes and a few supplies, you can help protect your family from the spread of germs.

Fun Facts

  • Thermometers have been used as a diagnostic tool since the sixteenth and seventeenth centuries.
  • Sir Thomas Clifford Allbutt, a British physician, introduced the first modern clinical thermometer in 1866.
  • The U.S. Environmental Protection Agency has launched an effort to ban mercury-filled health thermometers due to the risk of contamination if the thermometer breaks. The National Institute of Standards and Technology no longer calibrates and certifies mercury-filled health thermometers.

When Is It Time to Replace a Thermometer?

If you still have a glass mercury-filled thermometer and are concerned about possible breakage, it's time to investigate the newer types of thermometers. Glass thermometers are still available with a mercury-free metal alloy that registers the temperature.

Digital and infrared thermometers need new batteries or should be replaced when temperature digital displays lag or seem inaccurate. Your health provider or pharmacist can recommend the best type of thermometer or brand for your needs.

What You'll Need

Materials

  • Cotton balls or pads
  • Isopropyl alcohol
  • Anti-bacterial liquid soap
  • Cotton swabs
  • Disposable plastic tip covers (optional)
  • Paper towels

Instructions

How to Disinfect Non-Digital Oral and Rectal Thermometers

For extra precaution, clean and disinfect a non-digital oral and rectal thermometer both before and after use.

Warning

If you have digital or non-digital oral and rectal thermometers that look alike, take the time to label each container to prevent cross-contamination.

  1. Wash With Soap and Water

    Wash the thermometer with warm water and a few drops of anti-bacterial liquid soap.

  2. Rinse Well

    Rinse well with warm water to remove any soapy residue.

  3. Disinfect the Thermometer

    Dampen a cotton ball or pad with isopropyl (rubbing) alcohol. Be sure that the alcohol content is at least 60 percent.

    Wipe down the thermometer from tip to tip with the alcohol-soaked pad.

  4. Rinse and Dry

    Rinse the thermometer with warm water to remove any traces of the alcohol. Dry the thermometer with a paper towel.

  5. Store the Thermometer Properly

    Make sure that the thermometer is completely dry before storing to prevent the possible growth of bacteria.

    It's a good idea to clean the inside of any storage case periodically by wiping it down with a pad dipped in isopropyl alcohol. Allow the case to air-dry.

How to Disinfect Digital Oral and Rectal Thermometers

  1. Disinfect Before Each Use

    Dampen a cotton ball or pad with isopropyl (rubbing) alcohol and wipe down the entire thermometer from handle to tip. You can also use a disinfecting wipe to clean the thermometer.

  2. Rinse Well

    Always rinse with warm water to remove any traces of the disinfectant. Rinsing can be done by holding the thermometer under warm, running water or with a dampened paper towel. Take extra precaution not to saturate the digital display area.

  3. Air-Dry Before Storing

    Place the thermometer on a clean paper towel to air-dry.

How to Disinfect Ear Thermometers

Ear or tympanic thermometers have a tiny sensor in the tip that is inserted into the ear canal to detect temperature changes.

  1. Disinfect the Tip

    Dip a cotton swab into isopropyl (rubbing) alcohol and clean the tip well.

  2. Disinfect the Entire Thermometer

    Use a cotton pad dampened with isopropyl alcohol or a disinfecting wipe to clean the rest of the thermometer. Do not rinse the thermometer under running water to prevent damage to electronic parts.

  3. Air-Dry

    Allow the thermometer to air-dry completely before storing it.

How to Disinfect Infrared Thermometers

These thermometers measure body temperature using an infrared sensor without touching the skin on the forehead. They should still be disinfected to prevent the transfer of bacteria from hands or if the thermometer comes in contact with the forehead.

  1. Disinfect the Handle

    Wipe down the handle of the device with a disinfecting wipe or a cotton pad dipped in rubbing alcohol.

  2. Clean the Infrared Sensor Screen

    Use a cotton swab dipped in rubbing alcohol to clean the screen over the sensor.

  3. Air-Dry the Thermometer

    Allow the thermometer to air-dry completely before storing it in its case or medicine cabinet.