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Fever in Children

Published on May 10, 2024 at 8:00 / Updated on May 25, 2024 at 8:00

A child has a fever when the rectal temperature is 38.0°C or higher. Infections, gastrointestinal problems and immunizations are the most common causes of fever in children. High fever is not reflective of the severity of an illness. A child's behaviour is usually a better indication of how sick they are.

Taking a child's temperature

There are several ways to take a child's temperature including the rectal, oral, axillary (armpit), tympanic (ear) and temporal (forehead) methods.

AgeRecommended method
Birth to 2 years 1. Rectal
2. Axillary
From 2 to 5 years 1. Rectal
2. Tympanic, Axillary
Older than 5 years 1. Oral
2. Tympanic, Axillary

There are several types of thermometers. Easy to use and accurate, digital thermometers (oral and rectal use) are preferred over mercury thermometers, which are no longer recommended. While convenient, infrared ear thermometers can give lower readings and are not as accurate as rectal thermometers.

Normal temperature ranges measured at different body sites vary.

MethodFeverGeneral comments
RectalHigher than 38.0Higher than 100.4 Cover tip with lubricant.
Insert into rectum 2.5 cm.
OralHigher than 37.5Higher than 99.5Place under tongue and close mouth.
TympanicHigher than 38.0Higher than 100.4 Use clean probe every time.
Tug ear back, insert into ear canal.
Variation between different thermometers.
AxillaryHigher than 37.5Higher than 99.5 Use rectal or oral thermometer.
Place in centre of armpit with arm tucked against body.

See doctor if:

  • Fever lasts more than 72 hours
  • Rash, red blotches
  • Seizures
  • Lethargic, unresponsive
  • Fussy, irritable
  • Crying inconsolably
  • Vomiting repeatedly
  • Wheezing, coughing persistently

Babies younger than 3 months old with a fever should see a doctor or go to a hospital immediately.

Dos and don'ts

A child who is feverish should rest and drink plenty of fluids. Remove extra blankets and clothing so heat can leave the body. Avoid removing all clothing as they could start shivering, generating more body heat and causing their temperature to rise. Alcohol rubs and lukewarm sponge baths are not recommended.

Medication is not always needed. A child who continues to play and eat normally despite having a fever does not require medication. When treatment is required, the first choice is acetaminophen (Tempra®, Tylenol®). Do not give acetaminophen to a child younger than 3 months without first talking to your doctor. Ask the pharmacist to show you which strength and form are best suited for your child then calculate the appropriate dose based on your child's weight.

The second choice is ibuprofen (Motrin®, Advil®). Ibuprofen should only be given if the child is drinking and eating reasonably well. Do not give ibuprofen to children under 6 months without first speaking to your doctor. Ask the pharmacist to recommend a product and advise you on the exact dose. Unless specifically advised by a health professional, children and teenagers with a fever should never take acetylsalicylic acid (Aspirin®).

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