Traditionally placebo has been hidden from patients, but recent studies are looking at being truthful about placebos instead of blinding. This is referred to as “open-label” or “honest” placebos with full disclosure.


This unique study involved patients with chronic low back pain (CLBP) who were all advised on staying active with no other intervention; then 50% of the patients were randomly chosen to receive 2 placebo tablets, twice a day for weeks.

What is so crazy about this study is that the patients receiving the placebo pills were clearly informed that, “The pills given to you are inactive placebo tablets, but they could still have a powerful effect, and your body can automatically respond to placebo, a positive attitude is helpful, but not necessary, and the placebo must be taken faithfully.”


So what happened after taking the honest placebo tablets for 3 weeks?

Z Pill

The patients in the control group had a reduction in their pain score of 0.2 on the 0 to 10 point Numeric Rating Scales and had no change in their disability scores.


The patients receiving the honest placebo pills had a reduction in their pain score of 1.5 and a reduction in their back pain related disability of 2.9, which is remarkable.

At the end of the 3 weeks, the other 50% who were originally in the control group, were now also given the same honest placebo pills for 3 weeks. Same thing, with the addition of the honest placebo, the pain reduced an average of 1.5 and disability reduced by 3.4 which are considered large effect sizes.

What is unbelievable about the study is that 70% of the patients with CLBP admitted to being skeptical of gaining any benefit from the pills and 30% reported that they believed it would work; yet subjects in both groups showed improvements in pain and disability scores.


Clinical Relevance: This paper really turns things upside down. We always assume that studies must work so hard to keep the placebo a secret and subjects blinded, but it turns out full honest disclosure of placebo is also beneficial for patients with chronic LBP. The brain is sooo complex, it can release endogenous opioids even if it consciously knows it is being “fooled!”


Reference: Carvalho C Open-label placebo treatment in chronic low back pain: a randomized controlled trial. Pain. 2016 Dec;157(12):2766-2772.

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