Using an armpit thermometer offers a convenient and accessible way to measure body temperature. This method is especially useful when other temperature-taking approaches are challenging or uncomfortable, such as for infants and young children. Understanding how to properly take and interpret an armpit temperature provides valuable health information.
Why Armpit Temperature Differs
The armpit, or axilla, is an external body site. Unlike internal sites like the rectum or mouth, its temperature is a surface measurement, making it susceptible to ambient environmental conditions. Blood flow to the skin and air exposure can cause the armpit temperature to be lower than the body’s core temperature. An armpit reading reflects skin temperature rather than the stable internal temperature of vital organs.
This difference arises because the armpit does not fully enclose the thermometer, allowing heat loss to the surrounding environment. The temperature measured is not as insulated or consistent as readings from internal cavities. Its peripheral location means it will naturally show a cooler reading compared to more central body areas.
The Standard Adjustment for Accuracy
Armpit temperature readings are typically lower than internal body temperatures, so an adjustment is often recommended to estimate a more accurate core body temperature. Healthcare professionals advise adding 0.5°F (0.3°C) to 1°F (0.6°C) to an armpit reading. This adjustment helps bridge the difference between the armpit’s surface temperature and the body’s internal temperature.
Applying this adjustment is an estimation, as the exact difference can vary among individuals and situations. Some sources suggest adding at least one full degree Fahrenheit to the reading. This practice aims to provide a more comparable value to oral or rectal temperature measurements, which are considered more precise indicators of core body temperature.
Taking and Understanding Your Armpit Temperature
To obtain a reliable armpit temperature reading, follow these steps. First, ensure the armpit is dry, as moisture can affect the reading. Position the tip of a digital thermometer in the center of the armpit, ensuring direct contact with the skin and not clothing. Hold the arm down firmly against the body to secure the thermometer in place.
Allow the thermometer to remain in place until it beeps, typically about one minute for digital models. After adjusting the reading (adding 0.5°F to 1°F), a normal body temperature is generally around 98.6°F (37°C), though individual ranges can vary. An armpit temperature of 99°F (37.2°C) or higher, even without adjustment, is often considered a fever. If the adjusted temperature remains elevated, or if other concerning symptoms are present, consult a healthcare provider.