Fever

What is it?

What is a fever?

In simple terms, fever is a higher than normal body temperature - one that is over the normal range of 36°C to 37.5°C.

Doctors define a fever according to where the temperature is measured, because body temperature is different in different parts of the body. The medical definition of a fever is a temperature over 37.8°C in the mouth (oral temperature) or ear canal (aural temperature), over 37°C in the armpit (axillary temperature) or over 38.3°C in the rectum (rectal temperature).

Fevers are not harmful in themselves - unless they get very high - and they may even be beneficial in fighting off infection. However, they are a sign that your child may be ill and in need of treatment.

Why do fevers happen?

Fever is a symptom, not a disease. Usually, a fever means that your child has an infection.

When harmful organisms such as bacteria or viruses enter your child's body, fever-producing substances called "pyrogens" are released. These chemicals act on the body's internal thermostat in the brain, re-setting it to a higher internal temperature. The body then tries to "obey" the thermostat and raise its temperature by reducing blood flow to the skin and shivering. This is why people with a fever may feel shivery and cold. Often the body overshoots the mark and has to lose the excess heat, with the result that the person feels too hot and appears flushed and sweaty.

Most common causes of a fever:

A child can simply become overheated due to exercise, a hot bath or too much clothing. However, the commonest reason for a fever is an infection. Infections may be serious - even life-threatening - but fortunately, in developed countries, most fevers are due to minor infections that cure themselves.

Common infections that cause fever:

• Coughs, colds, flu
• Throat infection (e.g., tonsillitis)
• Ear infection
• Gastroenteritis (digestive tract infection)
• Urinary tract infection
• "Childhood viral illness" such as chickenpox, measles, rubella, roseola

Rare and serious causes of fever:

• Meningitis (brain infection)
• Pneumonia
• Bone or joint infection
• Allergic reaction (rare)