Fever (also known as pyrexia) is one of the most common medical signs and is characterized by an elevation of body temperature above the normal range of 36.5–37.5 °C (98–100 °F) due to an increase in the temperature regulatory set-point. This increase in set-point triggers increased muscle tone and chills. As a person’s temperature increases, there is, in general, a feeling of cold despite an increasing body temperature. Once the new temperature is reached, there is a feeling of warmth.
