Clinical Definition

Fever is a physiological response, usually to disease, characterized by elevated core body temperature outside the normal levels. The hypothalamus regulates body temperature. When a pyrogen triggers a fever, arachidonic acid metabolites are released. The metabolites affect the hypothalamus causing a complex, systemic response in the body, which then results in increased body temperature.

In Our Own Words

Although body temperature can vary slightly throughout the day, 98.6 degrees Fahrenheit is considered normal. A fever is an increased body temperature above the normal range. An area in the brain called the hypothalamus controls body temperature. When something is not right in the body, such as an infection, a complex response may take place, affecting the hypothalamus and increasing body temperature. Having a fever is not an illness in itself. Instead, it is a symptom and part of the body’s immune response to disease or illness.