Why Rectal Temperature?
Taking a rectal temperature is the most accurate way to measure body temperature in infants and young children, especially those under 3 years old. While it may seem intimidating at first, it's a simple, safe procedure that provides the most reliable reading when accuracy is critical—such as when evaluating fever in a young baby.
Rectal temperatures are considered the "gold standard" for young children because they most closely reflect the body's core temperature. This is particularly important for infants under 3 months, where even a slight fever (100.4°F/38°C or higher) requires immediate medical evaluation.
📌 Key Points: A rectal temperature reading is typically 0.5-1°F higher than oral or axillary (armpit) readings. A rectal temperature of 100.4°F (38°C) or higher is considered a fever.
When to Take a Rectal Temperature
✅ Recommended For:
- • Infants under 3 months (most important)
- • Children under 3 years when accuracy is crucial
- • Any age child when doctor specifically requests it
- • When other methods give inconsistent readings
- • Suspected serious illness requiring precise measurement
❌ Do NOT Use If:
- • Child has diarrhea (can be uncomfortable)
- • Recent rectal surgery or injury
- • Child has low platelet count or bleeding disorder
- • Child is receiving chemotherapy
- • Child strongly resists (consider alternatives for older children)
What You'll Need
Essential Supplies
- ✓ Digital thermometer (labeled for rectal use)
- ✓ Petroleum jelly or water-based lubricant
- ✓ Clean tissue or cloth
- ✓ Pen and paper to record temperature
Important Notes
- • Use digital, NOT glass thermometers
- • Label thermometer "for rectal use only"
- • Don't use same thermometer for oral temps
- • Replace thermometer if it looks damaged
Step-by-Step Instructions
Prepare the Thermometer
- • Wash thermometer with soap and water
- • Rinse thoroughly and dry
- • Turn on the thermometer
- • Wait for "ready" signal (usually a beep)
- • Apply a small amount of petroleum jelly to the tip
Wait for Right Timing
If your baby has just had a bath, been bundled in multiple layers, or been swaddled, wait 20-30 minutes before taking the temperature to get an accurate reading.
Position Your Child
Choose one of these positions:
Option A: Belly-Down Position
- • Place baby belly-down across your lap
- • Keep your palm on lower back for security
- • This position works well for squirmy babies
Option B: Back Position
- • Place baby face-up on firm surface
- • Gently bend legs toward chest
- • Hold legs with one hand against back of thighs
- • This position provides good visibility
Insert the Thermometer
- • Gently insert the lubricated tip into the rectum
- • Insert ½ to 1 inch (1.25 to 2.5 cm) deep
- • STOP if you feel any resistance
- • Never force the thermometer
- • The thermometer should slide in easily with lubricant
⚠️ Important: Only insert until the tip is fully in the rectum. Don't insert the entire thermometer—just the metallic tip portion.
Hold Steady
- • Keep thermometer in place with gentle pressure
- • Hold it between your second and third fingers
- • Cup your hand against baby's bottom for stability
- • Talk softly and soothingly to your baby
- • Keep baby still—don't let them wiggle
Wait for the Reading
- • Wait until you hear the beep or signal
- • Most digital thermometers take 10-30 seconds
- • Don't remove thermometer before signal
- • Keep baby calm and still during reading
Remove and Read
- • Gently remove thermometer when complete
- • Read the temperature display
- • Write down the number with time of day
- • Note if reading is 100.4°F (38°C) or higher
Clean Up
- • Wipe thermometer with tissue or cloth
- • Wash thoroughly with soap and warm water
- • You can also clean with rubbing alcohol
- • Dry and store in protective case
- • Label clearly "for rectal use"
Understanding the Results
✅ Normal Range
Rectal: 97.5°F to 100.3°F (36.4°C to 37.9°C)
⚠️ Low-Grade Fever
Rectal: 100.4°F to 101°F (38°C to 38.3°C)
🔴 Fever - Call Doctor
Rectal: 100.4°F (38°C) or higher
For infants under 3 months: ANY fever of 100.4°F (38°C) or higher requires immediate medical attention!
Tips for a Smooth Experience
🎯 Be Quick & Confident
Hesitation makes it harder. Move confidently but gently. The faster you complete it, the less uncomfortable for baby.
🗣️ Talk Soothingly
Keep talking to your baby in a calm, reassuring voice throughout the process. Your calm demeanor helps keep baby calm.
🎵 Use Distraction
Sing a song, make funny faces, or give baby a toy to hold. Distraction works wonders for older infants.
⏰ Choose Good Timing
Take temperature when baby is calm, not right after crying or feeding. Wait 20-30 minutes after bath time.
💧 Use Enough Lubricant
Don't skimp on the petroleum jelly. A well-lubricated thermometer slides in easily and comfortably.
🤝 Get Help if Needed
For squirmy babies, having another adult help hold baby still can make the process much easier and safer.
Common Concerns & Questions
Will it hurt my baby?
No. When done correctly with adequate lubrication, taking a rectal temperature is not painful. It may be briefly uncomfortable or surprising for baby, but it doesn't hurt. If your baby cries, it's usually from being held still, not from pain.
Is it dangerous?
No. Rectal temperature-taking is very safe when done properly. The key is gentle insertion, adequate lubrication, and never forcing the thermometer. Serious complications are extremely rare.
What if I see blood?
A tiny amount of blood on the thermometer tip is usually not concerning—it may just indicate minor irritation. However, if you see more than a tiny streak, or if it happens repeatedly, contact your pediatrician.
How often can I take it?
You can take rectal temperatures as often as needed to monitor fever, but there's no need to check constantly. Every 4-6 hours is typically sufficient unless your doctor advises otherwise.
Can I use the same thermometer for oral temps?
No. For hygiene reasons, use separate thermometers for rectal and oral temperatures. Label them clearly and store them separately to avoid confusion.
⚠️ When to Call the Doctor
Contact your healthcare provider immediately if:
- • Baby is under 3 months with rectal temperature of 100.4°F (38°C) or higher
- • Baby is 3-6 months with temperature above 101°F (38.3°C)
- • Baby appears very ill regardless of temperature
- • Fever lasts more than 24 hours in child under 2 years
- • Fever lasts more than 3 days in any child
- • You have concerns about your child's condition
⚠️ Medical Disclaimer
This article provides general information about taking rectal temperatures and is not intended to replace professional medical advice. Always follow your pediatrician's specific instructions for your child. If you're unsure about taking a rectal temperature or interpreting results, contact your healthcare provider.