Fever is a higher-than-normal body temperature. Normal temperature is usually defined as 98.6 degrees Fahrenheit (F) or 37 degrees Celsius (C). Many healthcare providers would say a child truly has a fever when his or her temperature is greater than 99.5 degrees F or 37.5 degrees C.
Normally, body temperature changes throughout the day. Exercise, stress, or dehydration may cause a child's temperature to go up. In these cases, it is not considered a true fever.
Fever is a symptom, not a disease. Fever helps the body fight infections by making its defense systems work more efficiently. Bacteria and viruses cannot live at higher temperatures and so are killed by fever.
In very young children, even minor ailments can create fevers of 105 degrees F or more. On the other hand, serious viral infections sometimes bring only moderate fevers.
Usually, fevers in children are caused by viral infections. The most common are colds, flu, and gastroenteritis, which tend to be more inconvenient than dangerous. Other viral illnesses in children include fifth disease, chickenpox, and other rash-related illnesses.
Some other common causes of fever in children include the following: