Your baby's fever: How do I take the temperature?

By Canadian Paediatric Society on August 22, 2011

How you take your child’s temperature will depend on your child’s age.

  • According to the Canadian Paediatric Society (CPS), the preferred method of taking temperature in a child under two years of age is a rectal temperature.
  • Second choice in children under two years of age is an axillary (armpit) reading.
  • For children between the ages of two and five, alternate methods to rectal temperature include ear or axillary. After age five, an oral temperature is accurate.
  • Make sure you are using the correct device. In other words, don’t use an oral thermometer if you are taking a rectal temperature and vice versa.

The Canadian Paediatric Society has the following tips:

  • An oral thermometer doesn’t usually work in children younger than five, simply because it is too hard for them to hold the thermometer in place.
  • While the axillary method is usually reliable, if you are convinced your child has a temperature and this method does not confirm it, it might be best to repeat the measure with a different method. With young children, using the armpit may be difficult because it’s hard to hold the thermometer in place with the arm closed tightly around the thermometer.
  • Ear thermometers can be complicated to use and are not suggested for use in children under two. Sometimes it is hard to get a seal in a young child’s ear with the probe, and the temperature might be underestimated.

What do I do next? 

The degree of a fever does not always indicate the severity of the illness. I always tell my patients to watch how the child is behaving. A child who is lethargic is often of more concern than a child who seems his/her usual self. Your doctor will want to know the history of the fever and will ask several questions:

  • When did the fever start?
  • How long has the fever been present?
  • Are there related symptoms such as a cough, headache and sore throat?
  • Has there been anyone else sick at home or has your child been with any contacts that are known to be ill?
  • Can your child eat or drink?
  • Are there any known underlying illnesses?
  • Was the child given an immunization in the past few days?

The degree of the fever does not always indicate the severity of the illness.

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)
  • Ear 35.8°C to 38°C (96.4°F to 100.4°F)
  • Armpit 34.7°C to 37.3°C (94.5°F to 99.1°F)

By Canadian Paediatric Society| August 22, 2011

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