From the Research
Infections cause fever as part of the body's immune response to pathogens, with the most recent and highest quality study suggesting that fever is a regulated increase in body temperature, resulting from an upward shift in the thermoregulatory set point, mediated by pyrogenic cytokines released from monocytes/macrophages in response to infection or trauma 1. When bacteria, viruses, or other microorganisms invade the body, immune cells detect their presence and release chemicals called pyrogens, particularly cytokines like interleukin-1, interleukin-6, and tumor necrosis factor. These pyrogens travel through the bloodstream to the hypothalamus in the brain, which functions as the body's thermostat. The pyrogens reset this thermostat to a higher temperature, triggering the body to increase heat production and reduce heat loss. This happens through mechanisms like shivering (to generate heat), blood vessel constriction (to reduce heat loss through the skin), and increased metabolic rate. The elevated body temperature serves several protective functions: it can directly inhibit the growth of some pathogens, enhance immune cell function, and speed up bodily reactions that help fight infection. Some key points to consider include:
- Fever is a complex physiological response that is aimed at facilitating survival of the host 2
- The causes, types, clinical management, and postoperative consequences of fever are important to understand 3
- Fever is part of an integrated host defense system, and that failure to generate a fever in response to infection is generally associated with a poorer prognosis 1 While fever is generally a helpful defense mechanism, extremely high fevers (above 103°F or 39.4°C) may require treatment with fever-reducing medications like acetaminophen or ibuprofen to prevent complications, as suggested by earlier studies 4, 5.