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What’s the best way to take a child’s temperature?

While you often can tell if your child is warmer than usual by feeling her forehead, only a thermometer can tell how high the temperature is. A digital thermometer can be used to take a rectal (in the bottom), oral (in the mouth), or axillary (under the arm) temperature. Your child’s doctor can recommend how to use it depending on your child’s age. Taking a rectal or oral temperature is more accurate than taking an axillary temperature.

Ways to use a digital thermometer by age

Child’s AgeRectalOralAxillary
Newborn to 3 monthsX
3 months to 3 yearsXX
4 to 5 yearsXXX
5 years and olderXX

Tympanic (ear) thermometers are another option for older babies and children. However, while it gives quick results, it needs to be placed correctly in your child’s ear to be accurate. Too much earwax can cause the reading to be incorrect.

While other methods for taking your child’s temperature are available, they are not recommended at this time. Ask your child’s doctor for advice.

Mercury thermometers should not be used. The American Academy of Pediatrics encourages parents to remove mercury thermometers from their homes to prevent accidental exposure to this toxin.

How to use a digital thermometer

If your child is younger than 3 years, taking a rectal temperature gives the best reading. The following is how to take a rectal temperature:

  • Clean the end of the thermometer with rubbing alcohol or soap and water. Rinse it with cool water. Do not rinse it with hot water.
  • Put a small amount of lubricant, such as petroleum jelly, on the end.
  • Place your child belly down across your lap or on a firm surface. Hold him by placing your palm against his lower back, just above his bottom. Or place your child face up and bend his legs to his chest. Rest your free hand against the back of the thighs.
  • With the other hand, turn the thermometer on and insert it 1/2 inch to 1 inch into the anal opening. Do not insert it too far. Hold the thermometer in place loosely with 2 fingers, keeping your hand cupped around your child’s bottom. Keep it there for about 1 minute, until you hear the “beep.” Then remove and check the digital reading.
  • Be sure to label the rectal thermometer so it’s not accidentally used in the mouth.
    Once your child is 4 or 5 years of age, you can take his temperature by mouth. The following is how to take an oral temperature: 
  • Clean the thermometer with lukewarm soapy water or rubbing alcohol. Rinse with cool water.
  • Turn the thermometer on and place the tip under his tongue toward the back of his mouth. Hold in place for about 1 minute, until you hear the “beep.” Check the digital reading.
  • For a correct reading, wait at least 15 minutes after your child has had a hot or cold drink before putting the thermometer in his mouth.
    Although not as accurate, if your child is older than 3 months, you can take his underarm temperature to see if he has a fever. The following is how to take an axillary temperature: 
  • Place the tip of a digital thermometer in your child’s armpit.
  • Hold his arm tightly against his chest for about 1 minute, until you hear the “beep.” Check the digital reading.

Fever and Your Child (Copyright © 2007 American Academy of Pediatrics, updated 9/07)