How to Take a Baby's Rectal Temperature

Generally, parents with young babies have a few thermometers on hand - an ear or underarm thermometer for a quick read and a rectal thermometer for when you need a second opinion. The rectal temperature is recommended by pediatricians across the board for precision.

When to Take a Rectal Temp Reading

If your thermometer shows a temperature above 99 degrees F, it’s a good idea to take your baby’s rectal reading as well to see exactly what you’re dealing with, as fever in an infant can be a real emergency.

For those who are new to the process, here’s a quick guide on how to approach this less glamorous parenthood moment.

1) Disinfect the thermometer

Wipe the end of your Kinsa Smart Thermometer with some rubbing alcohol, or soap and water. For baby’s comfort, consider applying a bit of petroleum jelly on the end to make it easier to insert.

2) Position baby properly

Place your baby on your lap or a firm surface, either on his stomach or on his back with his legs lifted up to his chest (think diaper-changing position). Place your hand on his lower back (if on his stomach) or on the back of his thighs (if on his back) to keep him still.

3) Insert tip 1/2 inch

Insert the tip of the thermometer ½-inch to 1-inch inside his anal opening. Hold it between 2 of your fingers while keeping your hand cupped around his bottom (you might need to squeeze his cheeks together to hold it in place).

4) Wait 8 seconds

Your temperature reading should be complete in less than 8 seconds. Remember, rectal temperatures tend to be about ½ a degree higher than oral and 1 degree higher than underarm readings. If you're using the Kinsa app and select the correct mode of temperature taking, everything is accounted for - you do not need to add anything to the number you see on the thermometer. If you'd like to take baby's temperature again to verify your result, be sure to wait 5 minutes first for the most accurate second reading.

5) Take action based on fever

It’s recommended that you call your doctor immediately if an infant less than 3 months old exhibits any sign of fever. At 3-6 months, call your doctor if your baby is experiencing symptoms in addition to a mild or moderate fever, and call your doctor immediately if fever is high. If paired, the Kinsa app will help provide guidance as well.

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Luckily, the Kinsa Smart Thermometer can be used orally, rectally or under the arm. The Kinsa QuickCare has a flexible comfort tip to provide the best rectal thermometer experience for your baby. You can find one at home.kinsahealth.com.