While there are many ways to take an adult's temperature, only a few methods are appropriate for infants. If your infant is younger than 3 months old, you should use the rectal method because it is the most accurate. You can use a digital thermometer under the arm or an ear thermometer for infants older than 3 months of age. If you have specific questions about checking your infant for a fever, call your doctor.
Rectally
Step 1
Find a digital rectal thermometer. A rectal thermometer with a wide handle that prevents you from inserting it more than an inch is a good choice.
Step 2
Clean the thermometer. To do so, simply use soap and water or dip the end in rubbing alcohol.
Step 3
Put a small amount of petroleum jelly on the end of the thermometer. This enables you to insert it more easily.
Step 4
Position your baby so you have easy access to his bottom. The specific position you select is a matter of personal preference, but it may include placing him on his stomach over your lap or on his back on a changing table with his legs up.
Step 5
Turn on the thermometer. Gently spread your baby's buttocks apart and insert the tip of the thermometer between 1/2 inch and an inch into the rectum. Keep one hand on the thermometer and the other on your baby to prevent her from wiggling.
Step 6
Remove the thermometer when it beeps. Read the temperature on the display.
Under The Arm
Step 1
Find a digital thermometer. You can use any digital thermometer for this purpose.
Step 2
Position the baby so you have easy access to his armpits. It may be useful to partially or completely undress him from the waist up.
Step 3
Press the button to turn on the thermometer. Lift the baby's arm and place the thermometer in the armpit area. Return the arm to its normal position. You may need to hold her arm down if she is active or wiggly.
Step 4
Wait for the thermometer to beep. Remove the thermometer and read the temperature on the display.
In the Ear
Step 1
Find a digital thermometer designed for use in the ear. Press the button to turn on the thermometer.
Step 2
Place one of the throwaway covers over the tip of the thermometer. Gently pull the infant's ear straight back and place the tip of the thermometer into the ear canal. Do not push hard or use force. Turn on the thermometer.
Step 3
Hold the thermometer until you hear it beep. Remove the thermometer from the ear opening and read the temperature on the display.
Tips and Warnings
- Distracting your infant with toys, books or singing a song as you take her temperature may prevent her from fussing or wiggling. Underarm, or axillary, temperatures are about one degree cooler than the body's actual temperature, so add a degree to estimate the infant's real temperature. Follow up with a rectal reading if you require a more accurate reading.
- Call a doctor if your infant has a rectal temperature of more than 100.4 degrees Fahrenheit and he is younger than 3 months of age or if he has a fever over more than 101 degrees if he is between 3 and 6 months old. If your infant is older than 6 months, call a doctor if he has a fever more than 102 degrees for more than two days or if he has a fever of 103 degrees or higher. Call a doctor if your infant has constant vomiting or diarrhea, dry mouth, high-pitched crying, swelling on the soft spot of her head, limpness, unresponsiveness, whimpering, wheezing, difficulty breathing, skin rash, pale appearance, no appetite, irritability or is pulling at her ears.
