Whether you’re checking for a fever, monitoring room temperature, or cooking, knowing how to use a thermometer correctly is essential. With so many types available—digital, infrared, ear, and mercury—it’s important to follow the right steps for precise results.
In this guide, we’ll walk you through the proper way to use different thermometers, safety tips, and common mistakes to avoid.
What is the thermometer?
An instrument used in medicine to gauge body temperature is the thermometer. It is a tool that helps to monitor changes in body temperature and is a crucial part of any medical kit.
Thermometers come in different types, including digital thermometers, mercury thermometers, and infrared thermometers.
What are The Different Types of Thermometers?
Digital thermometers are the most commonly used and are battery-powered. They provide quick and accurate temperature readings, and some models have features like fever alarms and memory storage for previous readings.
Mercury thermometers have a glass tube filled with mercury and provide accurate temperature readings. However, they have been phased out due to the potential health risks associated with the accidental breakage of the glass tube and the release of mercury.
Infrared thermometers use infrared technology to measure temperature and are often used in non-contact temperature measurements. They can measure body temperature from a distance and are useful for taking the temperature of young children or people who are sensitive to physical contact.
Uses of Thermometer & How to Use?
Thermometers can be used to measure body temperature, the temperature of liquids like milk or water, or the temperature of the environment like a room or an outside area. Using a thermometer is a simple process that can be done in a few steps.
Correct Way to Take Temperature
These are the major things to consider for using the correct way to take temperature for your use.
Clean the thermometer:
Before using the thermometer, ensure it is clean. If you are using a digital thermometer, use a clean cloth or cotton swab dipped in alcohol to wipe the tip of the thermometer. If you are using a glass thermometer, wash it with soap and water and rinse it with cool water.
Turn on the thermometer:
For digital thermometers, turn on the device by pressing the power button. For glass thermometers, shake the thermometer down to below the lowest temperature reading.
Place the thermometer:
Place the thermometer in the correct position. For oral temperature readings, place the thermometer under the tongue and ask the person to close their mouth.
For rectal temperature readings, lubricate the tip of the thermometer with petroleum jelly, insert the thermometer into the rectum, and hold it in place until the device beeps or the temperature reading is complete.
Wait for the thermometer to read the temperature:
Wait until the thermometer beeps or the reading is complete (usually a few seconds). Do not move or talk while waiting for the temperature reading.
Read the thermometer:
Read the temperature reading on the digital display or the line on the glass thermometer. Record the temperature and follow the necessary actions based on the results.
Clean the thermometer:
After using the thermometer, clean it with soap and water or an alcohol swab, depending on the type of thermometer used.
Different ways to use Thermometers
Types of Thermometers and How to Use Them
1. Digital Oral Thermometer
Best for: Mouth temperature readings (common for adults and children over 4).
Steps:
- Clean the probe with alcohol or soap and water.
- Turn it on and wait for the “ready” signal.
- Place under the tongue, close your mouth, and breathe through your nose.
- Wait for the beep (usually 10-30 seconds).
- Read the display and clean the thermometer afterward.
Pro Tip: Avoid hot or cold drinks 15 minutes before taking a reading.
2. Ear (Tympanic) Thermometer
Best for: Quick readings (especially for kids).
Steps:
- Pull the ear gently upward (for adults) or backward (for children) to straighten the ear canal.
- Insert the probe and press the button.
- Hold steady until it beeps (1-3 seconds).
- Check the reading on the screen.
Warning: Earwax or incorrect positioning can affect accuracy.
3. Forehead (Infrared) Thermometer
Best for: Non-contact temperature checks (great for babies).
Steps:
- Hold 1-2 inches away from the center of the forehead.
- Press the scan button and move across the forehead.
- Wait for the beep and check the result.
Note: Avoid sweating or direct sunlight for accurate readings.
4. Rectal Thermometer (for Babies)
Best for: Most accurate readings for infants.
Steps:
- Lubricate the tip with petroleum jelly.
- Gently insert ½ to 1 inch into the rectum.
- Hold in place for about 30 seconds (digital) or 2 minutes (mercury).
- Remove and read, then disinfect.
Safety Tip: Never use the same thermometer for oral and rectal use.
5. Mercury Thermometer (Old-School Glass)
Warning: Many countries discourage mercury thermometers due to toxicity risks. If you must use one:
- Shake it down below 96°F (35°C).
- Place under the tongue or armpit for 3-5 minutes.
- Read at eye level, rotating gently to see the mercury line.
Common Mistakes When Using a Thermometer
- Not waiting long enough (especially with older models).
- Using the wrong type (e.g., oral for rectal readings).
- Not cleaning between uses (can spread germs).
- Taking temperature after eating/drinking (alters oral readings).
When to Seek Medical Help
- Adults: Fever above 103°F (39.4°C) lasting more than 48 hours.
- Children: Fever over 100.4°F (38°C) in infants under 3 months.
Final Thoughts
Using a thermometer correctly ensures accurate readings, whether for health, cooking, or room temperature checks. Always follow the manufacturer’s instructions and keep your thermometer clean for reliable results.
It is crucial to adhere to the manufacturer’s recommendations for particular thermometers, and if in doubt, seek medical guidance for health care products
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