A noxious stimulus is a stimulus strong enough to threaten the body's integrity (i.e. cause damage to tissue). Noxious stimulation induces peripheral afferents responsible for transducing pain (including A-delta and C- nerve fibers, as well as free nerve endings) throughout the nervous system of an organism.
The ability to perceive noxious stimuli is a prerequisite for nociception, which itself is a prerequisite for nociceptive pain. A noxious stimulus has been seen to drive nocifensive behavioral responses, which are responses to noxious or painful stimuli. These include reflexive, escape behaviors, to avoid harm to an organism's body.