Objective: Choice may be an important influence on the effectiveness and side effects of medical treatments.
Purpose: We investigated the impact of having a choice of medication compared to no choice on both nocebo and placebo responding.
Methods: Sixty-one participants were randomly assigned to either choose between or be assigned to one of the two equivalent beta-blocker medications (actually placebos) for pre-examination anxiety.
Results: There was a greater nocebo response in the no choice group and an increased placebo response in the choice group. Participants in the no choice group attributed significantly more side effects to the tablet than the choice group (p = 0.045), particularly at the 24-h follow-up (p = 0.002). The choice group showed a stronger placebo response in heart rate than the non-choice group.
Conclusion: Not being given a choice of medication increased the nocebo effect and reduced the placebo response to the treatment.
Keywords: Choice; Medication efficacy; Nocebo effect; Placebo effect; Side effects.