It is usually a sign that your body is trying to fight an illness or infection. Infections cause most fevers. You get a fever because your body is trying to kill the virus or bacteria that caused the infection. Most of those bacteria and viruses do well when your body is at your normal temperature.

What causes pyrexia?

The most common causes of fever are infections such as colds and stomach bugs (gastroenteritis). Other causes include: Infections of the ear, lung, skin, throat, bladder, or kidney.

What causes fever pathophysiology?

Fever, or pyrexia, is an elevation in body temperature caused by a cytokine-induced upward displacement of the set point of the hypothalamic thermoregulatory center. The purpose of fever isn't completely understood, but small elevations in body temperature appear to enhance immune function and inhibit pathogen growth.