How to use an oral thermometer

Use these tips to get an accurate oral temperature on patients with infection, COVID-19, influenza, hypothermia or hyperthermia


A patient’s body temperature is an important vital sign as part of the secondary assessment, but it is usually reserved for patients with suspected fever from a viral or bacterial illness, hyperthermia or hypothermia. During an influenza epidemic or in the midst of the 2020 COVID-19 pandemic, a temperature with an oral, tympanic, temporal infrared, or rectal thermometer should be obtained for nearly every EMS patient.

Just like any patient assessment component, familiarity and competency with the skill improves with repetition, routine and continuing education. Fortunately, using a thermometer is a relatively easy skill to acquire. Working as an EMT and then paramedic in an urgent care for several years, I was required to check oral temperature on thousands of patients. Here are some of my tips for how to use an oral thermometer:

1. Know the equipment, including how to turn it on, how to insert the thermometer’s probe into a disposable probe cover and how to eject the probe cover into a trash container without touching the cover. All of my experience is with an earlier model of the Welch Allyn SureTemp electronic thermometer, which features removable, interchangeable oral/axillary and rectal probes.

During an influenza epidemic or in the midst of the COVID-19 pandemic, a temperature with an oral, tympanic, temporal infrared, or rectal thermometer should be obtained for nearly every EMS patient. (Photo/Greg Friese)
During an influenza epidemic or in the midst of the COVID-19 pandemic, a temperature with an oral, tympanic, temporal infrared, or rectal thermometer should be obtained for nearly every EMS patient. (Photo/Greg Friese)

Also, check the settings as many thermometers can report both Celsius and Fahrenheit. Many models can also be used to assess oral, axillary and rectal temperature. The correct setting, and probe, is required to have the most accurate reported temperature.

2. Wash your hands before and after using the thermometer. Assume that the device itself is as contaminated as any other surface in the ambulance, and during assessment, the patient is likely to exhale, sneeze or cough onto your hands.

Remember to clean the thermometer after the call. Do this at the same time you are cleaning the cot, blood pressure cuff, stethoscope and the other surfaces in the patient care compartment.

3. Consider wearing gloves. I think it is often unnecessary to wear gloves when palpating a pulse, auscultating a blood pressure or listening to lung sounds unless there are signs of blood or other potentially infectious material, I suspect the patient has an infection or I might touch something I will regret touching. While gloves may not completely eliminate the spread of infectious materials, they do serve as a good reminder to us that when on, to clean anything the gloves touch. Defer to your department’s policies for glove use on some or all patient contacts.

4. Cover the thermometer probe with a disposable probe cover without touching or handling the probe. The thermometer is multiple-use, but the covers are not. Covers are universally meant to be applied without having to touch the cover. Should you find that you need to touch the cover, you may be introducing a dirty cover into the patient’s mouth.

5. Insert the probe into the mouth and under the tongue. Visualize seating the distal end of the probe in the heat pocket that is between the tongue’s frenulum and jaw. If the patient is awake and able, the patient can hold the thermometer in place by closing their mouth and lips and pressing their tongue down on the probe. I prefer not to let the patient hold or remove the thermometer on their own. That way only my hands touch the device. But if a patient demands to hold the thermometer, they might be able to position it as well or better and it’s not likely worth conflict.

6. Instruct the patient to keep their mouth closed until the thermometer beeps or blinks, indicating the temperature. Leaving the mouth open creates temperature inconsistencies which may give you inaccurate information. If it takes longer than 10 seconds, confirm the device is powered on, and has working batteries or is connected correctly.

7. Stand to the side of the patient. Whether you are holding the thermometer in place or not, the patient may cough or sneeze – after all, you are taking a temperature because you suspect they are ill. If a patient is awake and continuously coughing, an axillary temperature can be taken by holding the probe between the upper arm and lateral chest wall.

8. Report the temperature to the patient. Most patients want to know their temperature, pulse and blood pressure. Go ahead and tell them. It’s not a secret. Also ask the patient if they know their normal temperature. While 98.6°F is considered normal, many patients are aware they consistently run above or below the average. Recent body temperature research is suggesting that normal might be closer to 97.5°F.

Other devices are available for assessing tympanic temperature (insertion in the outer ear canal) and temporal (forehead) infrared scan. This page from the University of Michigan explains the types of devices and their accuracy.

Body temperature, like any vital sign, is best assessed as a trend over time. One set of vital signs is merely interesting. Two sets of vital signs start to tell a story about how the patient’s conditioning is improving, worsening or responding to your interventions.

What are your tips for obtaining an oral temperature or for using a tympanic or infrared temporal device?

Thanks to Ginger Locke, BA, NRP; and Kevin Collopy, BA, NRP for reviewing and comment on a draft of this article

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