How to read a mercury thermometer for fever

To determine fever using a mercury thermometer, it is essential to follow standardized measurement procedures, identify the correct measurement site, obtain accurate readings, refer to established fever criteria, and eliminate potential interfering factors to precisely assess whether body temperature is abnormal. If body temperature consistently exceeds 38.5°C, or is accompanied by severe symptoms such as headache or vomiting, prompt medical attention is recommended.

1. Standardized measurement procedure: Before measuring, shake the mercury column down below 35°C. Ensure the probe makes close contact with the skin. For axillary (underarm) measurement, keep the arm tightly closed for 5–10 minutes. For oral or rectal measurements, follow the corresponding required durations to avoid inaccurate readings due to insufficient measurement time.

2. Identify the measurement site: The three commonly used sites are axillary, oral, and rectal. Normal temperature ranges vary by site: axillary—36–37.2°C; oral—36.3–37.5°C; rectal—36.5–37.7°C. As normal values differ by location, appropriate reference standards must be used to determine the presence of fever.

3. Read the value accurately: After measurement, hold the thermometer at the end opposite the mercury bulb. Position it horizontally under adequate light and slowly rotate it to locate the scale marking aligned with the top of the mercury column. Keep your eyes level with the scale to prevent reading errors caused by parallax.

4. Refer to fever criteria: A temperature exceeding the normal upper limit for the respective measurement site indicates fever. Temperatures from 37.3°C to 38°C indicate low-grade fever; 38.1°C to 39°C, moderate fever; and above 39.1°C, high fever. Classify the severity of fever according to these temperature ranges.

5. Eliminate interfering factors: Avoid drinking hot liquids, vigorous exercise, or applying cold or hot compresses to the measurement site before taking temperature. If any of these activities have occurred, wait 30 minutes before measuring to prevent external influences from affecting accuracy.

After use, clean the thermometer with a cloth and store it properly to prevent breakage and mercury leakage. When experiencing fever, drink plenty of warm water, maintain good indoor ventilation, wear loose clothing to aid heat dissipation, and adjust care measures appropriately based on body temperature.