Dosage and usage preferences for open-label placebos: An online survey among the general population

While open-label placebos (OLPs), i.e., placebos administered with full disclosure about their inert nature, have been found to improve various symptoms it is still unclear which OLP aspects contribute to this effect. Previous results suggest that survey respondents are generally open to trying OLPs. One possible modulator known from deceptive placebos is the expectation associated with perceptual features of a pill (e.g., its color and shape). Here, we aimed to assess respondents' preferences and expectations concerning OLP dosage form, intake frequency, and pricing for various OLP pills and symptoms.

Respondents were shown photographs of commercially available placebo pills and asked to indicate their preferences and expectations regarding these OLPs and their expected efficacy at improving various symptoms (acute pain, chronic pain, fatigue, cognition, mood, and sleep disturbances).

Respondents (N = 532) preferred an OLP intake frequency of once per day, despite expecting twice per day to be more effective. The expected efficacy and other ratings differed somewhat between pill shapes with a general preference for round white pills. Expectations also differed between symptoms to be treated and were highest for improving mood and sleep disturbances. Moreover, expectations correlated positively with the amount of money respondents were willing to pay for a package of OLPs, which was highest for chronic pain, followed by mood and sleep disturbances.

Respondents' preferences and expectations with respect to pill appearance, intake frequency, and treatable symptoms differ and should be considered when designing and personalizing OLP treatments to further optimize their efficacy.