Measuring body temperature is a common practice to assess health status, and one accessible method involves taking an underarm (axillary) temperature using a thermometer placed in the armpit. Many individuals wonder about the proper interpretation of these readings, particularly regarding whether any adjustments are necessary. This article aims to clarify common misconceptions surrounding underarm temperature measurements and provide practical guidance for their use.
The “Add a Point” Myth
A widespread belief suggests that one should add a degree to an underarm temperature reading to obtain an accurate body temperature. Current medical guidelines, however, indicate that this practice is no longer recommended. This historical misconception likely arose because underarm temperatures often register slightly lower than core body temperatures, prompting attempts to “correct” the reading. Modern digital thermometers are calibrated to provide accurate readings for the specific site where they are used, eliminating the need for manual adjustments.
This outdated guideline can lead to misinterpretations of a person’s actual temperature. Relying on an adjusted reading might result in unnecessary concern or, conversely, a delay in recognizing a true fever. The reading displayed on the thermometer is considered the correct measurement for that specific site.
Accuracy of Underarm Temperature
While convenient and non-invasive, underarm temperature readings are generally less accurate reflections of core body temperature than other methods. Oral and rectal temperatures typically provide readings closer to the true internal body temperature. Axillary temperatures tend to be lower than oral or rectal measurements, often by one to two degrees Fahrenheit. Rectal temperature is frequently considered the gold standard for accuracy, especially in infants and young children, due to its reliable representation of core body temperature.
For adults, underarm temperature is often used for screening rather than precise diagnostic evaluations. It can indicate a fever, but may not always reflect the exact degree of elevation as accurately as other methods. Factors like external temperature, recent physical activity, or technique can influence the reading. Therefore, while useful for initial assessment, a significantly elevated axillary temperature might prompt further measurement using a more accurate method, particularly if there are accompanying symptoms.
Taking an Underarm Temperature
To accurately measure underarm temperature with a digital thermometer, ensure the armpit is dry before placement. Moisture can interfere with the thermometer’s ability to register heat. Place the tip directly into the center of the armpit, ensuring good skin contact. Hold the arm down firmly against the body to keep the thermometer in place and prevent air from affecting the reading.
The thermometer should remain in place until it beeps, indicating the reading is complete. Environmental factors like a recent bath, vigorous activity, or ambient room temperature can temporarily influence the reading. If an underarm temperature indicates a fever (generally above 99.0°F or 37.2°C, though definitions vary), or if there are other concerning symptoms, consult a healthcare professional.