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Having a sick child is one of the most stressful times you will face as a parent. Babies and young children can’t always tell you when they aren’t feeling well. Watching your child for changes in their behaviour may help you know when your baby is getting sick. A fever is a common reaction that happens when your child’s body is fighting an infection.

Babies younger than 6 months old should see a doctor when they have a fever. Older children can be treated at home, provided they get lots of fluids and seem well otherwise. However, they should see a doctor if the fever lasts for more than 72 hours.1


Where to Take a Temperature

There are 4 different places that you can take your child's temperature:

  1. Rectal Method (in the rectum or "bum")
  2. Oral Method (in the mouth)
  3. Axillary Method (under the armpit)
  4. Tympanic Method (in the ear)

Temperature Taking Tips

  • Do not use a glass mercury thermometer because it contains a toxic substance.
  • Do not use an oral thermometer for a rectal temperature, or a rectal thermometer to take an oral temperature.
  • A digital thermometer can be used for either a rectal or an oral temperature.
  • Ear thermometers (tympanic) are expensive and can be difficult to use correctly.
  • Digital electronic pacifier thermometers and fever strips do not give accurate readings and are not recommended1.

Telephone Support

To speak with a Public Health Nurse from the Middlesex-London Health Unit, please call 519-663-5317.

  • Monday to Friday
  • 8:30 a.m. to 4:30 p.m.

Telephone questions after regular business hours

Call Telehealth Ontario to speak with a Registered Nurse at 1-866-797-0000; or TTY: 1-866-797-0007.

  • Free, confidential service you can call to get health advice or information
  • 24 hours a day, 7 days a week
  • Available in English or French

Table 1: Age and Recommended Temperature Taking Method


Recommended Method

Birth to 2 years old

1st choice: Rectal (most accurate)

2nd choice: Armpit

Between 2-5 years old

1st chioice: Rectal (most accurate)

2nd choice: Armpit, Ear

Older than 5 years

1st choice: Mouth (most accurate)

2nd choice: Armpit, Ear2

How to Take a RECTAL (bum) Temperature:

  • Recommended method for children 0 – 2 years of age.
  • Read the manufacturer’s instructions on how to use the thermometer.
  • Wash with cool, soapy water, then rinse with cool water and dry.1
  • Cover the end of the thermometer with a lubricating jelly such as petroleum jelly (Vaseline) – this makes it easier to insert into the anus.
  • Place your baby on his/her back and bring the knees up towards the chest.
  • Gently insert the thermometer into the rectum about 2.5 cm (1 inch), always holding onto it while it’s inserted into the anus (*never force the thermometer past any resistance as this could damage the wall of the bowel*).
  • Gently remove the thermometer after it beeps and read the screen.
  • If the temperature is 38°C or higher, your baby has a fever.1

How to Take an AXILLARY (armpit) Temperature:

  • This is used for young babies and children, but it is not as accurate as a rectal temperature. If the axillary temperature does not show a fever, but your child feels warm to touch, please do a rectal temperature whenever possible.
  • Use a rectal or oral thermometer.
  • Lift the arm away from the body and place the tip of the thermometer in the center of the baby’s armpit.
  • Make sure the baby’s arm is tucked snuggly against her body.
  • Leave the thermometer there until it beeps (about a minute), then remove it and read the temperature.
  • If the temperature is 37.5°C or higher, your baby has a fever.1
  • Clean the thermometer in warm (not hot) and soapy water; dry well1.
  • Axillary temperature is (also) recommended by the American Academy of Pediatrics as a screening test for fever in neonates because of the risk of rectal perforation with a rectal thermometer.

How to Take a TYMPANIC (ear) Temperature:

  • Tympanic thermometers are NOT recommended for children under the age of two.1
  • Gently tug on the ear, pulling it up and back. This will help straighten the ear canal and make a clear path to the eardrum, where the temperature is measured.
  • Gently insert the thermometer into the ear canal until it is fully sealed off.
  • Squeeze down and hold the button for 1 second (or as per manufacturer’s instructions).
  • Remove the thermometer and read the screen.
  • If the temperature is over 37.5°C or higher, your baby has a fever1.

How to Take an ORAL (mouth) Temperature:

  • Oral temperature taking works best when a child is able to keep the thermometer under their tongue and they won’t bite down on it (not recommended for children under 5 as it is difficult for them to hold the thermometer under the tongue).
  • No hot or cold drinks 30 minutes prior to taking an oral temperature as this can affect the results.
  • For the most accurate oral temperature reading, place the tip of the thermometer under your child’s tongue and have your child close their mouth.
  • Once the thermometer beeps, gently remove and read the screen.
  • If the temperature is 37.5°C or higher, your baby has a fever. 1
  • Wash the tip of the thermometer is warm (not hot) and soapy water, dry well1.

Caring for Your Child with a Fever

  • Keep your child as comfortable as possible.
  • Offer lots of fluids – offering small amounts more often is best.
  • Dress your child in light clothing – take off extra layers which can help bring the fever down. Remember not to take off all of the baby’s clothing as they may become cold and start to shiver, which can actually make the body heat back up.
  • Sponge bathing your child in lukewarm water is NOT recommended as the baby may become cold and start to shiver, which can actually make the body heat up more.
  • If the baby is older than 6 months, you can give your child medicine to help reduce the fever - Consult with your doctor or Health Care Professional about giving Acetaminophen (Tylenol, Tempra) to your child.  Always follow package directions and give the right amount based on your child’s weight and not their age.
  • Do NOT give Ibuprofen to babies under 6 months without first talking to your doctor.
  • Ibuprofen should only be given if your child is drinking reasonably well.  Do not alternate between using acetaminophen and ibuprofen as this can lead to dosing errors.1
  • Do NOT give Aspirin to treat your child’s fever - it has been linked to a severe condition called Reye’s Syndrome1.


Normal temperature range1


36.6°C to 38°C (97.9°F to 100.4°F)


35.5°C to 37.5°C (95.9°F to 99.5°F)


36.5°C to 37.5°C (97.8°F to 99.5°F)


35.8°C to 38°C (96.4°F to 100.4°F)

Watch your child closely during this time. If you notice any of the following, please call your doctor immediately:

  • Excessively fussy, cranky, or irritable.
  • Extremely sleepy or difficult to wake up.
  • Is unable to move or complains of a stiff neck.
  • Persistent wheezing or coughing.
  • Has a rash or any other signs that worry you.
  • Excessive vomiting or diarrhea1.
  • Has convulsions or a Febrile Seizure. 3

For more information go to Canadian Paediatric Society- Fever and temperature taking. Contact your Health Care Provider, if you have concerns.

Date of creation: December 12, 2012
Last modified on: July 13, 2017


1Canadian Paediatric Society. (2013). Fever and temperature taking Retrieved from Retrieved from
2Leduc, D. & Woods, S. (2013). Temperature measurement in paediatrics. Community Paediatrics Committee, Canadian Paediatric Society. Retrieved from