Ask an Expert: What does it mean if my child has a fever?

Young children frequently have elevation in body temperature or fever, but what is happening and why? 

First, it is important to recognize how young children are different than adults. In general, infants and children have a higher temperature than adults due to a greater surface-area-to-body-weight ratio as well as a higher metabolic rate. Thinking about the size of a young child’s head compared with their arms helps to illustrate the ratio difference. 

A small area of the brain called the hypothalamus helps to control body temperature like a thermostat for your home. Body messengers or cytokines increase in response to a trigger such as inflammation or infection and send messages to the hypothalamus to reset body temperature at a higher temperature. This part of the brain directs heat production and decreased heat loss through changes in the muscle, skin, heart, and breathing. As young children’s brains first respond to cytokines, they can overreact and cause higher fevers or changes in temperature that happen too quickly.

The exact measurement for a fever is determined by the age of the child and the site of the measurement. Many pediatricians will provide guidance to parents to define not only a fever, but also a fever of concern either by a higher measurement, quick change in temperature, or a persistence of the elevation in temperature. In general, the height of the fever isn’t as important as other signs of illness and the response to a fever-lowering agent does not help to distinguish the cause of the fever.