How long should a mercury thermometer be kept under the armpit to take a temperature?

Mercury thermometers are commonly used tools for measuring body temperature, and their working principle is based on the physical property of mercury expanding when heated and contracting when cooled. When using a mercury thermometer to measure axillary (underarm) temperature, attention should be paid to the duration of the measurement. Usually, to ensure accuracy of the measurement, the mercury end of the thermometer should be placed deep in the armpit, ensuring close contact with the skin, and the upper arm should be held tightly against the chest to secure the thermometer in place. Leave the thermometer undisturbed for approximately 5–10 minutes, and wait until the mercury column inside stabilizes before reading the result. This period ensures the thermometer has adequately detected the body temperature change, avoiding inaccurate readings caused by insufficient measurement time. Therefore, maintaining the correct posture and sufficient measurement time are key to ensuring accurate results when measuring axillary temperature.