Fever

Overview

A fever occurs when your body temperature rises above normal. It is not a condition unto itself but an indication that your body is responding to a viral or bacterial infection or some other illness. Your temperature rises in order to help the body's immune system fight off the foreign invader by making its environment inhospitable.

On average a ·normal' body temperature is 98.6 degrees F or 37 degrees C. However because your temperature will rise and fall throughout the course of the day it could be slightly lower or higher at any given time. A mild fever is no cause for concern. However whenever your temperature rises to a range of between 102 F and 103 F (38.8 and 39.4 C) or higher it may be a sign of a serious illness and you should consult a doctor. Any fever that goes above 105 degrees Fahrenheit (40.5 C) is a life-threatening medical emergency and you should call 9-1-1.

Symptoms

The degree of a fever does not necessarily tell you how serious the illness is; the child's behaviour is generally the most important factor. Contact a doctor if your child:

  • is excessively cranky fussy or irritable
  • is excessively sleepy lethargic or unresponsive
  • is persistently wheezing or coughing
  • has a fever and is less than six months old
  • has a fever higher than 39°C (102°F)
  • has a fever and a rash
  • has any other signs of illness that worry you

You can tell if there is a fever by taking the child's temperature with a thermometer. While the mercury thermometer is still the gold standard for accuracy there are safety considerations for children under 5 who may bite down and break the glass. The Canadian Pediatric Society recommends that for young children (birth-age 5) a rectal temperature will give the best reading. Lay the child on his or her stomach put a bit of petroleum jelly on the end of the thermometer and then carefully insert it no more than one inch into the rectum. Keep the baby still to prevent injury. Remove the thermometer after three minutes to get a reading. The CPS brochure How to take a child's temperature offers step-by-step instructions on how to get an accurate reading.

A digital thermometer can also be used for rectal and oral temperatures. It is made of unbreakable plastic is easy to read and measures temperature faster than glass. When using a digital thermometer hold it in place until it gives its signal. Ear thermometers which you can use on children older than 2 years are available but are expensive.

Your child has a fever when:

  • the rectal temperature is 38.5°C (101.3°F) or higher
  • the oral temperature is 38°C (100.4°F) or higher
  • the temperature in the armpit is 38°C (100.4°F) or higher (these temperatures are generally not accurate)

Cause

A fever usually suggests a viral or bacterial infection. Some of the more common causes are:

  • Influenza
  • Common cold
  • Earaches
  • Bronchitis
  • Strep throat
  • Urinary tract infections

In most cases your doctor will be able to identify the precise cause of the fever by evaluating other symptoms. If for example you are also sick to your stomach and vomiting you could have gastroenteritis. A cough that produces thick yellow or green phlegm on top of a fever might suggest pneumonia. Only a doctor can properly diagnose and treat your particular condition. If you have a low-grade fever that persists for three weeks or more but have no other symptoms your doctor may recommend a variety of tests to help find the cause.

Treatment

Medical treatment will depend on the cause of the fever. Your doctor may prescribe antibiotics for bacterial infections. For viral infections the best treatment is often rest and plenty of fluids. Remove extra blankets so heat can leave the body and help lower the temperature. Do not take off clothing however because it is possible to become too cold and start shivering which produces more body heat causing the temperature to rise again. Alcohol baths and rubs are not recommended.

Your doctor may also suggest taking over-the-counter medications such as acetaminophen (Tylenol others) or ibuprofen (Advil Motrin others) to lower a very high fever. Adults may also use aspirin. But never give aspirin [acetylsalicylic acid (ASA) to a child or teenager with a fever as this can increase the risk of Reye's syndrome a rare but potentially fatal liver and brain disorder.

Complications

Approximately four percent of children under age 5 experience fever-induced seizures (febrile seizures). The signs of febrile seizures which occur when a child's temperature rises or falls rapidly include a brief loss of consciousness and convulsions. Although these seizures can be extremely alarming most children don't experience any lasting effects.