Acetaminophen relieves pain by elevating the pain threshold, that is, by requiring a greater amount of pain to develop before it is felt by a person. It reduces fever through its
action on the heat-regulating center
of the brain. Specifically, it tells the center to lower the body's temperature when the temperature is elevated. Acetaminophen relieves pain in mild arthritis but has no effect on the underlying inflammation, redness and swelling of the joint.