Acetaminophen, an organic compound with the chemical formula C8H9NO2, is the metabolite of phenacetin in vivo. It reduces the synthesis and release of prostaglandin PGE1, bradykinin and histamine by inhibiting the hypothalamic thermoregulatory center prostaglandin synthetase. PGE1 mainly acts on the nervous center, and its reduction will lead to the decrease of central temperature setting point, and the body surface temperature receptors feel relatively hot, and then achieve the antipyretic effect through nerve regulation by causing peripheral vascular dilation and sweating. Its effect of inhibiting prostaglandin synthesis in the central nervous system is similar to that of aspirin, but its anti-inflammatory effect is weak. It has no effect on platelet and coagulation mechanism.