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Fever and temperature taking

Highlights
  • Babies younger than 6 months old should see a doctor when they have a fever.
  • Do not use a mercury thermometer. If it breaks, you might be exposed to this toxic substance.
  • Medication is not always needed to reduce a child’s temperature.

When your child is sick with an infection (bacterial or viral), it is common to have a fever. Fever will not hurt your child. Usually, it goes away after 72 hours (3 days).

Babies younger than 6 months old should see a doctor when they have a feverOlder children can be treated at home, as long as they get enough liquids and seem well otherwise. However, they should also see a doctor if their fever lasts for more than 72 hours.

There are several ways to take your child’s temperature:

  • rectal method (by the rectum or ‘bum’)
  • oral method (by the mouth)
  • axillary method (under the armpit)
  • temporal artery method (forehead)
  • tympanic method (in the ear)

Which method should I use?

The right method depends on your child’s age. It’s important that the measurement is accurate. For instance, taking a rectal temperature is still the best way to get an exact reading for children under 2 years of age. Although taking a temperature under the armpit isn't as reliable, it might let you know whether your child has a fever. Products for taking temporal artery temperature (sweeping thermometer across your child’s forehead) at home have not yet been shown to be accurate or reliable enough.

Use this chart to help you decide which method to use.

Age Recommended method
Birth to 2 years 1st choice: Rectum (for an accurate reading)
2nd choice: Armpit
Between 2 and 5 years 1st choice: Rectum (for an accurate reading)
2nd choice: Ear, armpit
Older than 5 years 1st choice: Mouth (for an accurate reading)
2nd choice: Ear, armpit

Temperature-taking tips

  • Do not use a mercury thermometer. If it breaks, you might be exposed to this toxic substance.
  • Do not use an oral thermometer to take a rectal temperature, or a rectal thermometer for oral temperature taking.
  • A digital thermometer can be used for both rectal and oral temperature taking. It's made of unbreakable plastic, is easy to read and measures temperature quickly.
  • Ear thermometers are expensive and can be hard to use.
  • Fever strips are not recommended because they do not give accurate readings.

To get an accurate reading of your child’s temperature, you’ll need to make sure it’s done right. Here’s how:

Rectum

This is the most reliable way to ensure a fever is not missed.

  • Clean the thermometer with cool, soapy water and rinse.
  • Cover the silver tip with petroleum jelly (such as Vaseline).
  • Place your baby on his back with his knees bent.
  • Gently insert the thermometer in the rectum, about 2.5 cm (1 inch), holding it in place with your fingers.
  • After about 1 minute, you will hear the beep.
  • Remove the thermometer and read the temperature.
  • Clean the thermometer.

Mouth

The oral method is not recommended for children younger than 5 years old because it is hard for them to hold the thermometer under their tongue for long enough.

  • Clean the thermometer with cool, soapy water and rinse.
  • Carefully place the tip of the thermometer under your child’s tongue.
  • With your child’s mouth closed, leave the thermometer in place for about 1 minute, until you hear the beep.
  • Remove the thermometer and read the temperature.
  • Clean the thermometer.

Armpit

The armpit (axillary) method is usually used to check for fever in newborns and young children, but it’s not as accurate as a rectal temperature. If an axillary temperature does not show a fever but your child feels warm and seems unwell, take a rectal measurement.

  • Use a rectal or oral thermometer.
  • Clean the thermometer with cool, soapy water and rinse.
  • Place the tip of the thermometer in the centre of your child’s armpit.
  • Make sure your child’s arm is tucked snugly against her body.
  • Leave the thermometer in place for about 1 minute, until you hear the "beep."
  • Remove the thermometer and read the temperature.
  • Clean the thermometer.

Ear

Though quick to use, the ear (tympanic) method can give temperature readings that are too low, even when the manufacturer’s directions are followed. It is not as reliable or accurate as rectal temperature taking.

  • Use a clean probe tip each time, and follow the manufacturer’s instructions carefully.
  • Gently tug on the ear, pulling it back. This will help straighten the ear canal, and make a clear path inside the ear to the ear drum.
  • Gently insert the thermometer until the ear canal is fully sealed off.
  • Squeeze and hold down the button for one second.
  • Remove the thermometer and read the temperature.

What is a normal temperature?

The following chart will tell you if your child has a fever. The normal temperature range varies and depends on the way you took your child’s temperature.

Method Normal temperature range
Rectum 36.6°C to 38°C (97.9°F to 100.4°F)
Mouth 35.5°C to 37.5°C (95.9°F to 99.5°F)
Armpit 34.7°C to 37.3°C (94.5°F to 99.1°F)
Ear 35.8°C to 38°C (96.4°F to 100.4°F)

The degree (height) of a fever does not tell you how serious your child’s illness is—how your child is acting is usually a better sign. A child with a mild infection can have a high fever, while a child with a severe infection might have no fever at all. 

What can I do if my child has a fever?

Keep your child comfortable, and offer plenty of fluids.

If your baby has a fever, remove extra blankets and clothing so heat can leave her body and help lower the body temperature. But don’t take off all your child's clothes, because she may become too cold and start shivering, which makes more body heat and will cause her  temperature to rise again.

Sponging your child with tepid (lukewarm) water, alcohol baths and rubs is not recommended.

Medication is not always needed to reduce a child’s temperature. In fact, the best reason for giving your child medicine is not to reduce the fever, but to relieve any aches and pains.

Acetaminophen (such as Tylenol, Tempra, Panadol and others) is a suitable medication for a fever. Unless your doctor says otherwise, you can give the dose recommended on the package every 4 hours until your child's temperature comes down. The temperature usually comes down in 1 hour and then rises again. If this happens,  the medication may have to be repeated at the recommended time. Do not give more than 5 doses in 24 hours.

Alternatively, you can give your child ibuprofen, which is found in products such as Advil and Motrin. Be sure to follow the directions on the package. Ibuprofen can be given every 6 to 8 hours — up to 4 times in a 24-hour period. Do not exceed the recommended dose.

  • Ibuprofen should only be given if your child is drinking reasonably well.
  • Do not give ibuprofen to babies under 6 months without first talking to your doctor.

Do not alternate between using acetaminophen and ibuprofen as this can cause your child to be at risk for liver failure.

A child or teenager with a fever should not be given aspirin [acetylsalicylic acid (ASA)]

If the fever is due to chickenpox, influenza or certain other viral infections, taking aspirin can increase the risk of Reye's syndrome. This is a very serious condition that can damage the liver and brain.

Contact your health care provider if your child:

  • Has a fever and is less than 6 months old.
  • Has a fever for more than 72 hours. 
  • Is excessively cranky, fussy or irritable.
  • Is excessively sleepy, lethargic or does not respond.
  • Is persistently wheezing or coughing.
  • Has a fever and a rash or any other signs of illness that worry you.


Reviewed by the following CPS committees:
Community Paediatrics Committee

Last Updated: September 2013

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