How to Take Your Temperature: A Complete Guide to Accurate Readings

Taking your temperature accurately is an essential skill for monitoring your health and detecting potential illness. Whether you’re checking for a fever or tracking symptoms, knowing the proper technique for using different types of thermometers ensures you get reliable results that can help guide your healthcare decisions.

This comprehensive guide will walk you through everything you need to know about measuring body temperature at home, including the different methods available, step-by-step instructions, and important tips for accuracy.

Understanding Normal Body Temperature

Before learning how to take your temperature, it’s helpful to understand what’s considered normal. The average body temperature for adults is typically around 98.6°F (37°C), but normal ranges can vary between 97°F (36.1°C) and 99°F (37.2°C).

Several factors can influence your body temperature, including:

• Time of day (temperature is typically lowest in early morning and highest in late afternoon)
• Age (older adults tend to have lower body temperatures)
• Activity level (exercise can temporarily raise temperature)
• Menstrual cycle (temperature may be higher during ovulation)
• Food and beverage consumption
• Environmental conditions

A fever is generally defined as a temperature of 100.4°F (38°C) or higher.

Types of Thermometers

Always use a digital thermometer to check your temperature. Glass mercury thermometers are no longer recommended due to the potential for mercury exposure or ingestion and have been phased out in most healthcare settings.

Digital Thermometers

These are the most common and versatile type, using electronic heat sensors to record body temperature. They can be used orally, rectally, or under the armpit and are suitable for all ages.

Digital Ear Thermometers (Tympanic)

These devices use infrared technology to measure the temperature inside the ear canal. They provide quick readings and are convenient for children and adults.

Temporal Artery Thermometers (Forehead)

These infrared scanners measure the temperature of the temporal artery on the forehead, offering a non-invasive and quick method.

Pacifier Thermometers

Designed specifically for infants, these look like regular pacifiers but contain temperature sensors.

General Safety and Hygiene Guidelines

Before taking a temperature with any type of thermometer, follow these important precautions:

• Carefully read the manufacturer’s instructions that came with your specific thermometer model
• Wash your hands thoroughly with soap and warm water before handling the thermometer
• Clean the thermometer before and after each use with rubbing alcohol or soap and lukewarm water
• Never use the same thermometer for both oral and rectal temperatures without proper labeling and thorough cleaning
• Wait at least 30 minutes after eating, drinking, exercising, or bathing before taking a temperature
• If you’ve recently taken fever-reducing medication, consult your healthcare provider about the appropriate timing for temperature checks
• Replace thermometer batteries as needed and check that the device is functioning properly

How to Take an Oral Temperature

Oral temperature measurement is one of the most accurate and commonly used methods for adults and older children who can safely hold a thermometer in their mouth.

Step-by-Step Instructions:

1. Wait if necessary: If you’ve recently consumed hot or cold foods or beverages, wait at least 30 minutes before taking your temperature to ensure accurate results.
2. Prepare the thermometer: Turn on the digital thermometer and wait for it to be ready. Some models will display “L” or “0” when ready.
3. Position correctly: Place the thermometer tip under your tongue, slightly to one side. The tip should be positioned in the pocket of tissue beneath the tongue, not on top of it.
4. Hold in place: Close your mouth around the thermometer and breathe normally through your nose. Keep your lips sealed and hold the thermometer steady.
5. Wait for the signal: Keep the thermometer in place for the recommended amount of time or until you hear a beep indicating the reading is complete (typically 30-60 seconds).
6. Read and record: Remove the thermometer carefully and read the number on the display. Record the temperature along with the time and method used.
7. Clean the thermometer: Wash the thermometer with soap and lukewarm water or wipe it down with rubbing alcohol.

Note: Oral thermometers should not be used for children under 4 years old, as they may not be able to keep the thermometer properly positioned.

How to Take an Ear Temperature

Digital ear thermometers offer quick and convenient readings, making them popular for home use. However, proper technique is crucial for accuracy, as earwax, ear infections, or incorrect positioning can affect results.

Step-by-Step Instructions:

1. Prepare the device: Turn on the digital ear thermometer and ensure it has a clean, disposable probe cover if your model requires one.
2. Position the ear: For adults, gently pull the outer ear up and back to straighten the ear canal. For children under 3, pull the ear straight back. This helps ensure the probe has a clear path to the eardrum.
3. Insert gently: Place the thermometer gently in the ear canal, following the manufacturer’s instructions for how far to insert it. Don’t force it too deeply.
4. Hold steady: Keep the thermometer firmly in place and aimed at the eardrum until you hear the beep indicating the reading is complete (usually just a few seconds).
5. Read the result: Remove the thermometer carefully and check the digital display.
6. Clean or replace covers: Dispose of the probe cover if used, or clean the thermometer according to manufacturer instructions.

Important tips: Don’t use an ear thermometer if the person has an ear infection, significant earwax buildup, or has recently been lying on their ear, as these factors can affect accuracy.

How to Take a Temporal Artery Temperature

Temporal artery thermometers are non-invasive and can be particularly useful for sleeping children or when other methods aren’t practical.

Step-by-Step Instructions:

1. Prepare the area: Make sure the forehead is clean, dry, and free from sweat, hair, or hats. Sweat can cool the skin and result in a falsely low reading.
2. Turn on the device: Power on the digital thermometer and wait for it to be ready.
3. Position correctly: Place the probe flat against the center of the forehead, midway between the eyebrow and hairline.
4. Sweep across: While pressing the scan button, gently sweep the thermometer across the forehead from one temple to the other, following the manufacturer’s specific instructions. Some models require you to also scan behind the ear.
5. Read the result: Release the button and check the temperature displayed on the screen.
6. Clean the probe: Wipe the sensor with a clean cloth or alcohol wipe.

Note: Results may be less accurate if the person is sweating or has been in a very hot or cold environment recently.

How to Take an Armpit Temperature

Armpit (axillary) temperature measurement is the least invasive method and can be used when other methods aren’t suitable. However, it’s typically less accurate than oral, rectal, or ear measurements, often reading about one degree lower than oral temperature.

Step-by-Step Instructions:

1. Prepare the area: Make sure the armpit is dry. Moisture can affect the reading.
2. Turn on the thermometer: Power on the digital thermometer and wait for it to be ready.
3. Position correctly: Place the thermometer tip in the center of the armpit, ensuring it touches skin and not clothing.
4. Hold the arm down: Hold the arm firmly against the body, pressing the elbow against the chest to keep the thermometer in place.
5. Wait for completion: Keep the thermometer in position until you hear the beep indicating the reading is complete (typically 30-60 seconds, possibly longer than oral readings).
6. Read and adjust: Remove the thermometer and read the number. Remember that armpit temperatures are generally about 1 degree Fahrenheit lower than oral temperatures.
7. Clean the thermometer: Wash with soap and lukewarm water or wipe with rubbing alcohol.

How to Take a Rectal Temperature

Rectal temperature measurement is considered one of the most accurate methods and is often recommended for infants and young children. It tends to read about 0.5 to 1 degree Fahrenheit higher than oral temperature.

Step-by-Step Instructions:

1. Use the right thermometer: Use a digital thermometer specifically designated for rectal use. Mark it clearly and never use it orally.
2. Prepare supplies: Have petroleum jelly or water-based lubricant ready to coat the thermometer tip.
3. Position the person: For infants, lay them on their back with legs bent toward the chest, or place them stomach-down across your lap. For older children and adults, lying on the side with knees bent is most comfortable.
4. Lubricate the tip: Apply a small amount of lubricant to the thermometer tip.
5. Insert gently: For infants, insert the thermometer about 0.5 to 1 inch into the rectum. For older children and adults, insert 1 to 1.5 inches. Never force it.
6. Hold in place: Keep the thermometer steady until it beeps (usually about 30 seconds). Hold the thermometer and keep your hand on the child if taking an infant’s temperature.
7. Remove and read: Gently remove the thermometer and check the display.
8. Clean thoroughly: Wash the thermometer carefully with soap and hot water or rubbing alcohol.

Safety note: Never leave a child unattended with a thermometer in place. Stop immediately if you meet any resistance when inserting the thermometer.

Tips for Accurate Temperature Readings

To ensure you get the most accurate temperature readings possible:

• Use the same method consistently: When tracking temperature over time, use the same method and same thermometer for best comparison
• Record all details: Note the temperature, time of day, method used, and any symptoms present
• Take multiple readings: If a reading seems unusual, wait a few minutes and take another measurement to confirm
• Check calibration: Some digital thermometers can be tested for accuracy by placing them in ice water (should read 32°F or 0°C)
• Replace when needed: Digital thermometers typically last several years but should be replaced if they give inconsistent readings or show signs of damage
• Consider age-appropriate methods: Different age groups may require different methods for optimal accuracy and safety

Recommended Temperature-Taking Methods by Age

The most appropriate method for taking temperature can depend on age:

• Newborns to 3 months: Rectal temperature is most accurate and recommended
• 3 months to 4 years: Rectal, ear, or armpit temperature. Temporal artery thermometers can also be used
• 4 years to adult: Oral, ear, armpit, or temporal artery methods are all appropriate
• Adults: Any method can be used, with oral and temporal artery being most common

Common Mistakes to Avoid

Avoid these common errors that can lead to inaccurate readings:

• Taking temperature immediately after eating, drinking, or physical activity
• Not waiting for the thermometer to signal completion
• Using a dirty or uncalibrated thermometer
• Incorrect positioning of the thermometer
• Taking armpit temperature over clothing
• Using an ear thermometer when earwax is blocking the ear canal
• Taking forehead temperature when the person is sweating
• Not holding oral thermometers under the tongue properly
• Comparing temperatures taken using different methods without accounting for normal variations

When to Seek Medical Attention

While taking your temperature at home is useful for monitoring health, certain situations require professional medical evaluation:

For Adults:

• Temperature of 103°F (39.4°C) or higher
• Fever lasting more than three days
• Fever accompanied by severe headache, stiff neck, confusion, difficulty breathing, chest pain, or persistent vomiting
• Fever in someone with a weakened immune system
• Any concerning symptoms regardless of temperature

For Infants and Children:

• Rectal temperature of 100.4°F (38°C) or higher in infants under 3 months
• Temperature of 102°F (38.9°C) or higher in children 3 months to 3 years
• Fever lasting more than 24 hours in children under 2 years
• Fever lasting more than 3 days in older children
• Fever accompanied by unusual lethargy, irritability, rash, difficulty breathing, dehydration, or seizures
• Any fever in a newborn (under 3 months) requires immediate medical attention

If you’re unsure whether a fever requires medical attention, contact your healthcare provider for guidance. They can advise whether you should seek immediate care, schedule an appointment, or monitor symptoms at home.

Maintaining Your Thermometer

Proper care of your thermometer ensures accuracy and longevity:

• Store in a cool, dry place away from direct sunlight
• Keep in a protective case to prevent damage
• Replace batteries promptly when the low battery indicator appears
• Never immerse non-waterproof digital thermometers in water
• For ear thermometers, stock up on disposable probe covers
• Check the manufacturer’s recommendations for cleaning specific models
• Test accuracy periodically, especially if readings seem unusual
• Keep instruction manuals accessible for reference

Conclusion

Knowing how to properly take your temperature is a valuable health monitoring skill that can help you detect illness early and make informed decisions about seeking medical care. By following the appropriate technique for your chosen method, maintaining good hygiene practices, and understanding what constitutes a normal versus concerning temperature, you can confidently monitor your health and that of your family members at home.

Remember that while home temperature monitoring is useful, it should never replace professional medical advice. If you have concerns about a fever or other symptoms, always consult with a healthcare provider who can properly evaluate your condition and recommend appropriate treatment if needed.

Sources:

• Mayo Clinic – Thermometers: Understand the options
• Centers for Disease Control and Prevention – Temperature Measurement
• American Academy of Pediatrics – Fever Management
• MedlinePlus – Body Temperature Norms
• U.S. Food and Drug Administration – Thermometers