Open-Label Placebos: Why Are They Effective?

Tom G. Bartol, NP


December 07, 2018

Open-Label Placebo Effects

The outcomes of placebo treatments have shown significant improvements in many double-blind, randomized trials when the patient does not know whether the treatment is placebo or real. A new study[1] suggests that placebos given "open label," with the recipient's full knowledge that it is a placebo, may still have a significant measurable clinical effect.

In one small trial, patients were told that it was not known whether the placebo would help their condition, but were also told, "Let's see what happens." In a treatment trial for irritable bowel syndrome, patients who received the placebo had a 60% relative improvement versus 35% with usual care.[2] Other trials showed three times relative efficacy of placebo versus usual treatment for low back pain and cancer-related fatigue.[3,4]

Kaptchuk and colleagues[1] found that two thirds of patients surveyed would be willing to take an open-label placebo if recommended. More research is encouraged to determine a clear role for open-label placebo.


The placebo effect has been well studied; it's been determined that even after the administration of an inert substance, the effect is real. The effects of placebo are thought to be due to the "therapeutic encounter, with its rituals, symbols, and interactions."[5] Even active medications have a placebo effect beyond their chemical effects. With open-label placebo, the rituals and interactions do not build expectations to the same degree as a double-blind trial. The participants were told that the placebo contained only fiber.

Another study[6] looking at open-label placebo treatment of allergic rhinitis symptoms found that positive expectations did not contribute to the efficacy of placebo despite a significant placebo effect. Participants in these trials overwhelmingly deny having any initial positive expectation that the placebo will work but express hope, because nothing else has helped their condition to this point. The placebo effect in these open-label trials may be related to the desperation of people who have not experienced relief with conventional treatment.

The concept of an open-label placebo is intriguing. Although somewhat counterintuitive, the role of open-label placebos should be clarified more with further research. Future studies should explore the "desperation effect," to determine whether it exists during the initial treatment of a condition in addition to treatment with open-label placebo after all other therapies have failed.


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