Naloxone does not alter the perception of pain induced by electrical and thermal stimulation of the skin in healthy humans.

It has been hypothesized that, in the absence of acute or chronic pain, a tonically active system exists involving opioid peptides, which ensures a certain level of pain insensitivity. Although various studies have failed to support this concept, it has been reported that in conditions of both experimentally induced and clinical pain, high doses of the opioid antagonist naloxone induced a state of hyperalgesia and thus seemed to set off this hypothetical system. Lower doses were, however, without effect or even acted as analgesics.