The most common cause of a fever in a child is a viral infection. A bacterial infection is a much less common cause.
The body’s natural reaction to infection with a virus or bacteria is to raise the temperature inside the body (the core temperature). This helps to kill the infection.
Other causes of high body temperature include:
- immunisations - these usually cause only mild fever
- wrapping a baby in too many warm layers of clothing, or bedding
Will a fever harm my child?
Fever is a normal way for a child to fight an infection. Being hot may make your child feel unhappy or uncomfortable, but the high temperature is very unlikely to cause any long-term problems.
Some children have convulsions when they have fevers. These may look very worrying, but even these febrile convulsions are very unlikely to cause long-term problems.