What Is an Axillary Temperature?
An axillary (armpit) temperature is taken by placing a thermometer under your child's arm, in the armpit area. This method is comfortable, non-invasive, and easy to perform, making it a popular choice for parents. While not as accurate as rectal temperatures, axillary readings are useful for general temperature screening and monitoring, especially in older infants and children.
Axillary temperatures are typically about 0.5-1°F lower than oral or rectal temperatures because the armpit is further from the body's core. Despite being less precise, this method is perfectly acceptable for routine temperature checks in children over 3 months when a fever is not the main concern.
📌 Key Point: An axillary temperature of 99°F (37.2°C) or higher is considered a fever. This is lower than the fever threshold for rectal (100.4°F) or oral (100°F) readings.
When to Use Axillary Temperature
✅ Good Choice For:
- • Newborns when rectal is not possible
- • Routine temperature screening
- • Children who resist other methods
- • Quick checks when child feels warm
- • Home monitoring of known illness
- • Any age when comfort is priority
⚠️ Not Recommended When:
- • Baby is under 3 months and precision is critical
- • Evaluating serious illness where exact temp matters
- • Doctor specifically requested rectal temperature
- • Initial reading shows fever (confirm with more accurate method)
What You'll Need
Simple Supplies
- ✓ Digital thermometer
- ✓ Pen and paper to record temperature
- ✓ That's it! No lubricant needed
💡 Note: Use a digital thermometer, not a glass or mercury thermometer. Digital thermometers are safer, faster, and easier to read.
Step-by-Step Instructions
Remove Clothing
Remove your child's shirt or onesie so you have direct access to the armpit. The thermometer must touch bare skin for an accurate reading.
Check Armpit is Dry
Make sure the armpit is dry. Moisture can affect the reading. Gently pat dry if needed.
Turn On Thermometer
Turn on the digital thermometer and wait for the "ready" signal (usually a beep or display indicator).
Place Thermometer
Place the thermometer tip in the center of the armpit, pointing it toward the body (not out to the side).
- • Tip should be completely covered by skin
- • Position it in the deepest part of armpit
- • Aim the tip toward the chest, not downward
Hold Arm Close
Press your child's arm snugly against their body to hold the thermometer in place:
- • Arm should be close to the side
- • Create a "seal" around the thermometer
- • Hold arm steady—don't let it move
- • For babies, gently hold their arm against their side
Wait for Signal
Keep the thermometer in place until you hear the beep or see the completion signal:
- • Usually takes 30-60 seconds
- • Some thermometers take up to 2 minutes
- • Don't remove early or reading will be inaccurate
- • Keep child calm and still during reading
Read and Record
- • Remove thermometer when complete
- • Read the temperature on the display
- • Write down the number and time of day
- • Note if it's 99°F (37.2°C) or higher
Clean Thermometer
- • Wipe with clean tissue or cloth
- • Wash with soap and water or rubbing alcohol
- • Dry and store in protective case
Understanding Axillary Temperature Results
✅ Normal Range
Axillary: 96.6°F to 98.6°F (35.9°C to 37.0°C)
⚠️ Possible Fever
Axillary: 99°F to 99.5°F (37.2°C to 37.5°C)
Consider confirming with a more accurate method (rectal or oral)
🔴 Fever - Confirm & Monitor
Axillary: 99°F (37.2°C) or higher
For infants under 3 months: Confirm any fever with rectal temperature and call doctor
💡 Remember: Axillary temperatures run about 1 degree lower than rectal temperatures. A reading of 99°F axillary would be equivalent to about 100°F rectal.
Tips for Accurate Readings
☀️ Room Temperature
Take temperature in a room-temperature environment. Very hot or cold rooms can affect the reading.
⏰ Wait After Activity
Wait 20-30 minutes after your child has been bundled up, had a bath, or been very active before taking temperature.
🤗 Keep Child Calm
Crying or struggling can raise body temperature slightly. Try to keep your child calm during the reading.
📍 Proper Placement
Ensure the thermometer tip is in the center of the armpit, not poking out or against clothing.
🎯 Complete the Reading
Wait for the beep! Removing the thermometer too early will give an inaccurate (usually lower) reading.
🔄 Retake if Unsure
If the reading seems off or child moved during measurement, take it again to confirm.
Common Mistakes to Avoid
❌ Taking temp through clothing
Always place thermometer on bare skin. Clothing creates an air gap that affects accuracy.
❌ Wet armpit
Moisture from sweat or bathing will lower the reading. Dry the armpit first.
❌ Removing too soon
Wait for the thermometer to beep. Early removal gives falsely low readings.
❌ Loose arm position
Arm must be held snugly against body. An open armpit lets heat escape, lowering the reading.
❌ Wrong thermometer position
Thermometer should point toward chest, not hang down toward floor.
Frequently Asked Questions
Q: Is axillary temperature accurate enough?
For routine screening and monitoring in children over 3 months, yes. It's less accurate than rectal or oral methods but sufficient for determining if a child has a fever. For critical decisions (like whether a newborn needs emergency care), use a more accurate method.
Q: Which armpit should I use?
Either one is fine. Some prefer the left armpit if the child is right-handed (and vice versa) as that arm may be calmer, but there's no medical difference. Use whichever is more comfortable for you and your child.
Q: Can I use a temporal (forehead) scanner instead?
Temporal artery thermometers are another option and can be very accurate when used correctly. They're more expensive but offer quick, non-invasive readings. Follow the manufacturer's instructions carefully for best results.
Q: Why does my thermometer give different readings each time?
Axillary temperatures can vary more than other methods because of factors like room temperature, how snugly the arm is held, and how long you wait. Small variations (0.1-0.3°F) are normal. Larger differences suggest the thermometer wasn't positioned correctly or reading wasn't complete.
⚠️ Medical Disclaimer
This article provides general information about taking axillary temperatures and is not intended to replace professional medical advice. Always follow your pediatrician's specific instructions. For infants under 3 months with any concern about fever, use rectal temperature measurement and contact your healthcare provider.