Living in a COVID-19 pandemic means we are often taking the temperatures of ourselves and our children.  I know this is often a required step as part of a daily screening tool for children who attend day care or preschool.  I have to take Madi’s temperature every time I bring her to preschool.  

What Is A Fever?

A fever is a sign that your body is fighting an infection.  A fever is not an illness, it means your body is responding to an illness.  A fever usually goes away within 3 days. 

The following chart will help you determine if your child has a fever depending on where and how you take their temperature.  

LocationNormal Temperature Range CelsiusNormal Temperature Range Fahrenheit 
Rectum36.6 to 38°C97.9 to 100.4°F
Armpit36.5 to 37.5°C97.8 to 99.5°F
Mouth35.5 to 37.5°C95.9 to 99.5°F
Ear35.5 to 38°C96.4 to 100.4°F
Forehead35.7 to 37.5°C96.3 to 99.5°F

A fever is a temperature above the upper limit of the temperature range for that location of the body.  How high the temperature is does not corelate with how sick your child is.  How your child is acting while having a fever is a better tell of how sick they are.

How To Take A Temperature

Rectum

  • The most accurate method of taking a child’s temperature up to 5 years old
  • Using a clean digital thermometer, lubricate the end with petroleum jelly
  • Place your child on their back with their knees bent up to their chest
  • Insert the silver tip of the thermometer about 2.5cm (1 inch) into the rectum
  • Press the button and wait until you hear the beep
  • Remove the thermometer and read the temperature
  • Clean the thermometer with soap and water

Armpit

  • Most common method used for babies and young children
  • Using a clean digital thermometer, place the tip in the centre of your child’s armpit
  • Hold your child’s arm snugly against the side of their body
  • Press the button and wait until you hear a beep
  • Remove the thermometer and read the temperature
  • Clean the thermometer with soap and water
  • This is my preferred method with Madi and George

Mouth

  • Only recommended for children 5 years and older
  • Using a clean digital thermometer, place the tip under your child’s tongue
  • Leave the thermometer in place with their mouth closed until you hear a beep
  • Remove the thermometer and read the temperature
  • Clean the thermometer with soap and water

Ear

  • Not recommended for children under 2 years old
  • More difficult to get an accurate reading and more likely to give low readings
  • Put a clean probe tip onto the end of the thermometer
  • Gently tug your child’s ear up and back to straighten the ear canal
  • Place the tip of the thermometer in the ear and wait until you hear a beep
  • Remove the thermometer and read the temperature
  • Throw away the probe tip

Forehead

  • Not endorsed as an accurate method of measuring temperature in babies or young children at this time
  • Can be used as a screening measurement, but a temperature taken rectally or under the arm would be recommended to confirm temperature if your child is unwell

Thermometer Tips

Do not use the same thermometer for rectal, armpit, and oral use.  You should have a thermometer specifically labelled for rectal use only if you use this route. 

Do not use mercury thermometers.  They are not safe if the glass breaks.  

Fever strips are not accurate.  Do not use these.  

Babies younger than 6 months old should be assessed by a doctor if they have a fever.  Older children can be treated at home so long as they get enough fluids and seem well otherwise.  Any fever that lasts longer than 3 days warrants a visit to the doctor.  

This post was co-authored by Erin Manchuk, BScPharm, BCGP and Stephanie Liu, MD, MSc, CCFP, BHSc.