The placebo effect and homeopathy

BackgroundLike other forms of medicine, including Complementary and Alternative Medicine (CAM), homeopathy elicits expectations in patients. The physician–patient relationship, personal and comprehensive treatment and lack of adverse effects are elements in creating positive expectations. Other elements may be associated with negative expectations.MethodsWe conducted a systematic literature review on placebo and nocebo effects in acupuncture and homeopathy using Medline.ResultsFindings on the psychophysiological and neuromediating mechanisms of the placebo–nocebo phenomenon are reviewed. Studies of these effects reveal how expectations and unconscious conditioning can be measured by imaging and EEG methods. They result in significant, non-specific therapeutic effects, which may confuse the evaluation of the specific therapeutic effects treatment, hampering selection of the simillimum.ConclusionsDirections for future research on non-specific therapeutic effects of homeopathy to improve clinical practice and clinical research are discussed.