[Appearances are not deceptive: clinical evidence and new research approaches to open-label placebo].

The efficacy of placebo effects is proven in experimental, clinical and meta-analytical studies. However, harnessing placebo effects in clinical treatment contexts is hampered legally and ethically, since it has been considered necessary to conceal the inert nature of a placebo application. Interestingly, the results of recently published small, randomized trials suggest that patients can experience symptom relief after taking pills that they know lack any medication. In particular, these so-called open-label placebos (OLP) improved strongly fluctuating and individually distressing complaints such as gastrointestinal, neurological, psychosomatic and pain symptoms. Although the mechanisms are largely unknown, the open-label placebo application might be a promising way of fostering placebo effects in clinical settings. Initial study protocols already provide schedules for OLP use as an additional treatment in opioid use disorders. Likewise, the reduction of side effects, conversion effects or withdrawal symptoms through OLP applications in pharmacologically active treatments appear to serve as appropriate therapy goals. Further mechanistic studies are urgently needed to investigate the thus far only hypothetically proposed underlying mechanisms of OLP.