The process of fever starts from the stimulation of white blood cells(monocytes, lymphocytes, and neutrophils) by exogenous pyrogens in the form of toxins, inflammatory mediators, or immune reactions. The white blood cells will secrete chemicals known as endogenous pyrogens (IL-1, IL6, TNF-α, and IFN). Exogenous pyrogens and endogenous pyrogens will stimulates the hypothalamic endothelium to produce prostaglandins.
Prostaglandins are formed later will increase the thermostat benchmark in the hypothalamic thermoregulation center. The hypothalamus will perceive the current temperature as lower than the current temperature the new benchmark so it triggers the mechanisms for Increases in heat include shivering, skin vasoconstriction and voluntary mechanisms such as wearing a blanket.