Objective: An open-label placebo (OLP) is a placebo treatment in which the patient is aware that the treatment is a placebo. OLPs are considered effective for reducing pain, and previous studies have shown a stronger placebo effect for placebo acupuncture than for placebo pills. In this study, the authors compared the analgesic effects of OLP pills, OLP acupuncture, and a no treatment condition in healthy participants, and then examined the factors contributing to the OLP effect. Design: Randomized controlled crossover trial. Settings/Location: College of Korean Medicine, Kyung Hee University, Seoul, Republic of Korea. Subjects: 34 healthy participants. Intervention: Participants received three different treatments ("OLP-pill," "OLP-acupuncture," and "no treatment") on three separate days in random order. Outcome Measurements: Before and after the treatment, heat pain stimuli were applied to the participants' hands, and pain tolerance, intensity, and unpleasantness were measured using a visual analog scale (range, 0-10). Results: Data of 31 participants were included in the analysis. The authors found significant analgesic effects of the placebo pill and placebo acupuncture in the OLP condition. Regression analyses revealed that expectations regarding treatment and practitioner identity influenced the analgesic effects of OLP acupuncture. There was no adverse event. Conclusions: Expectations regarding treatment and practitioner identity influenced the analgesic effect of placebo acupuncture without deception. These findings provide new information regarding the cognitive factors underlying pharmacologic and nonpharmacologic treatments. Clinical Trial Registration Number: KCT0004928.
Keywords: acupuncture; open-label; pill; placebo; regression analysis.