Relevance: Informing patients about potential adverse events as part of the informed consent may facilitate the development of nocebo-driven drug adverse events (nocebo side effects). Objective: To investigate whether informing about the nocebo effect using a short information sheet can reduce nocebo side effects. Methods: A total of N = 44 participants with weekly headaches for at least 6 months were recruited using the cover story of a clinical trial for a headache medicine. In reality, all participants took a placebo pill and were randomized to the nocebo information group or the standard leaflet group. Participants were instructed to read the bogus medication leaflet entailing side effects information shortly before pill intake. The nocebo group additionally received an explanation about the nocebo effect as part of the leaflet. Questionnaires were completed at baseline, 2 min, and 4 days after the pill intake. We conducted general linear models with bootstrap sampling. Baseline symptoms were included as a covariate. Results: Most participants (70.5%) reported nocebo side effects at 2 min. Participants who received the nocebo information ( n = 24) reported less nocebo symptoms than the control group ( n = 20) (estimated difference: 3.3, BCa 95% CI [1.14; 5.15], p = 0.01, Cohen’s d = 0.59). Baseline symptoms, perceived sensitivity to medicine, and side effect expectations each moderated the group effect (estimated difference in slope: 0.47, BCa 95% CI [0.19; 0.73], p = 0.001, d = 0.75; 1.07 [0.27; 1.61], p = 0.006, d = 0.73; 1.57 [0.38; 2.76], p = 0.02, d = 0.58). No group differences were found at 4-day follow-up. After revealing the actual aim of the study, 86% of the participants evaluated the nocebo information to be helpful in general. Conclusions: Results provide the first evidence that informing about the nocebo effect can reduce nocebo side effects.

Relevance: Understanding patients’ informational needs and adapting drug-related information are the prerequisites for a contextualized informed consent. Current information practices might rather harm by inducing nocebo effects.Objective: To investigate whether informing about the nocebo effect using a short information sheet affects patients’ need for information about antidepressants.Methods: A total of 97 patients taking recently prescribed antidepressants (≤4 months intake) were recruited over the internet and randomized to receiving either a one-page written information about the nocebo effect or a control text about the history of antidepressants. After experimental manipulation, informational needs about the side effects and mechanisms of antidepressants were assessed with 3 and 7 items on categorical and 5-point Likert scales. Group differences in informational needs were calculated with Chi-square tests and ANOVAs.Results: Patients received antidepressants for depression (84.5%) and/or anxiety disorders (42.3%). Three participants (6.0%) of the nocebo group reported previous knowledge of the nocebo effect. After the experimental manipulation, participants in the nocebo group reported a reduced desire for receiving full side effect information [X(4,97)2 = 12.714, Cramer’s V = 0.362, p = 0.013] and agreed more frequently to the usefulness of withholding information about possible side effects [X(4,97)2 = 14.878, Cramer’s V = 0.392, p = 0.005]. Furthermore, they desired more information about the mechanisms of antidepressants (F = 6.373, p = 0.013, partial η2 = 0.063) and, specifically, non-pharmacological mechanisms, such as the role of positive expectations (F = 16.857, p < 0.001, partial η2 = 0.151).Conclusions: Learning about the nocebo effect can alter patients’ informational needs toward desiring less information about the potential side effects of antidepressants and more information about general mechanisms, such as expectations. The beneficial effects of including nocebo information into contextualized informed consent should be studied clinically concerning more functional information-seeking behavior, which may ultimately lead to improved treatment outcomes, such as better adherence and reduced side effect burden.