Several studies have looked at the use of various pain testing models to investigate the effects of chronic opioid therapy and changes in pain perception. A systematic review of the literature was performed to identify clinical studies incorporating measures of hyperalgesia in patients on chronic opioid therapy. This review was aimed at finding the optimal testing modality to evaluate pain threshold and tolerance to external stimuli, including mechanical (pressure, touch, injection), thermal (cold/heat), and electrical. Although the results did not reveal any one method with sufficient power, several prospective studies evaluating hyperalgesia with heat pain ratings have shown some promising results; two studies revealing significant changes in heat responses for opioid treatment groups, and one study demonstrating lower heat pain perception values following an opioid taper. The latter study is unique in that research pertaining to changes in pain sensitivity on patients following an opioid taper is lacking. Little is known at this juncture how pain thresholds change to opioid dose reductions and following completion of a taper.