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Discharge Instructions: Taking a Rectal Temperature (Child)

You take a rectal temperature by placing a thermometer in your baby’s bottom. This method is more accurate than most other methods. But do this only when instructed by your baby’s healthcare provider. Use the steps on this sheet as a guide.

For babies and toddlers, use the rectal thermometer with care. A rectal thermometer may accidentally poke a hole in (perforate) the rectum. Insert it gently. Label it and make sure it's not used in the mouth. It may pass on germs from the stool. Follow the product maker’s directions for correct use. If you don’t feel OK using a rectal thermometer, ask the healthcare provider what type to use instead. When you talk with any healthcare provider about your child's fever, tell him or her which type you used.

Hand holding digital rectal thermometer.

Hands using digital rectal thermometer to take baby's temperature.

Get the thermometer ready

  • Be sure to use a digital thermometer that is specifically designed for rectal use.

  • Remove the cover from the thermometer.

  • Wash the thermometer with warm soapy water; then rinse with clear water.

  • Wipe the thermometer dry or let it air dry.

  • Smear a bit of petroleum jelly or water-based lubricant on the tip.

Find a comfortable position for holding your baby

  • Put your baby on his or her back on a firm surface. Hold the baby’s ankles and lift both legs, as if changing a diaper.


  • Place your baby face down across your lap.


  • Use one hand to part the baby’s buttocks.

Take the temperature

  • Follow the specific directions for using your digital thermometer.

  • Gently slip the tip of the thermometer into the opening where bowel movements leave baby’s body (the rectum) no farther than ½ inch to 1 inch.

  • Hold the thermometer in place until it beeps.

  • Slide the thermometer out. Read the temperature on the digital display. Normal rectal temperature is about 97.6°F (36.4°C) to 100.2°F (37.9°C).

  • Before putting the thermometer away, clean it with soap and warm water.

Follow-up care

Follow up with your child’s healthcare provider, or as advised.

When to seek medical care

Call your child's healthcare provider right away if your child has any of the following:

  • Bleeding from the area where you took the temperature

  • Fever (see Fever and children, below)

  • Your child has had a seizure

  • Your child seems very ill, is listless, or is acting very fussy

Fever and children

Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

  • Rectal. For children younger than 3 years, a rectal temperature is the most accurate.

  • Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The provider may want to confirm with a rectal temperature.

  • Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.

  • Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The provider may want to confirm with a rectal temperature.

  • Mouth (oral). Don’t use a thermometer in your child’s mouth until he or she is at least 4 years old.

Below are guidelines to know if your young child has a fever. Your child’s healthcare provider may give you different numbers for your child. Follow your provider’s specific instructions.

Fever readings for a baby under 3 months old:

  • First, ask your child’s healthcare provider how you should take the temperature.

  • Rectal or forehead: 100.4°F (38°C) or higher

  • Armpit: 99°F (37.2°C) or higher

Fever readings for a child age 3 months to 36 months (3 years):

  • Rectal, forehead, or ear: 102°F (38.9°C) or higher

  • Armpit: 101°F (38.3°C) or higher

Call the healthcare provider in these cases:

  • Repeated temperature of 104°F (40°C) or higher in a child of any age

  • Fever of 100.4° (38°C) or higher in baby younger than 3 months

  • Fever that lasts more than 24 hours in a child under age 2

  • Fever that lasts for 3 days in a child age 2 or older

Online Medical Reviewer: Donna Freeborn PhD CNM FNP
Online Medical Reviewer: Heather Trevino
Online Medical Reviewer: Liora C Adler MD
Date Last Reviewed: 4/1/2020
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