Best methods for accurate readings
For newborns, the most reliable and recommended methods are rectal or axillary (armpit) measurements, with rectal readings being the gold standard for accuracy. Use a digital thermometer designed for infants.
How to take a rectal temperature:
- Use a clean digital rectal thermometer and apply a small amount of lubricant.
- Lay the baby on their back or stomach across your lap, gently insert the thermometer tip about 1/2 inch (1–1.5 cm) into the rectum, and hold steady until it beeps.
- Clean the thermometer thoroughly after use.
Axillary (armpit) readings are less accurate but can be used as a quick screen; press the thermometer snugly under a dry armpit for a longer time.
When to call the doctor
- Any rectal temperature of 100.4°F (38°C) or higher in an infant under 3 months warrants immediate medical attention.
- For babies 3–6 months with a fever and fussiness or poor feeding, contact a pediatrician.
- Also seek care for fever plus lethargy, breathing problems, persistent vomiting, or rash.
Always follow device instructions and consult your pediatrician if you’re unsure which method to use. Having a reliable thermometer and knowing how to use it will give you confidence in responding quickly to health concerns.