Using the placebo effect: how expectations and learned immune function can optimize dermatological treatments.

The role of placebo and nocebo effects-that is positive or negative treatment effects that are entirely a consequence of the patient's expectations and beliefs about a treatment outcome in terms of efficacy, safety, usability or side effects-has been shown for almost all types of diseases and physiological response systems. Evidence for the relevance of placebo and nocebo effects in dermatology is also increasing, particularly for symptoms of itch and learned (conditioned) immune function. In addition, increasing knowledge is available about the neurobiological mechanisms of action, such as the role of the dopaminergic system. Studies on this topic offer innovative perspectives to unravel the multifactorial pathways of treatment effects and to use research designs for experimental research that provide full insight into the role of placebo and nocebo effects. Moreover, intervention strategies can be developed for dermatology practice that optimize regular treatments with innovative non-pharmacological treatment strategies (e.g. optimized doctor-patient communication and treatment adherence, or prevention of nocebo reactions with regard to adverse side effects). In addition, evidence on learned immune function offers new pathways to optimize pharmacological treatments (e.g. dosage adjustments and conditioning of physiological responses), the ultimate goal being to prevent individual treatment failures and maximize regular treatment effects.