Placebo analgesia: friend or foe?

The magnitude of placebo analgesia is influenced by environmental and perceptual factors. Environmental factors include past exposure to effective analgesic agents and verbal suggestions and cues that foster a perception of being given an effective treatment. Environmental factors, in turn, influence the proximate psychologic mediators of placebo analgesia, which include decreased desire for and increased expectations of pain relief. Strategies to maximize placebo analgesic effects in clinical practice could focus on using verbal suggestions and external cues to increase expectations of pain relief and/or decrease the perceived need for pain reduction. Placebo analgesic effects could be minimized in clinical trials by avoiding these same suggestions and cues.