The bottle literally said placebo. They took it anyway.

Randomised controlled trial (RCT). 80 people. 3 weeks (21 days), August 2009 - April 2010.

A trial. Chance decided who did what.

Who: 80 adults with irritable bowel syndrome (Rome III, IBS-SSS >=150) at one Boston academic centre (Beth Israel Deaconess); 70% women, mean age 47; recruited via ads for 'a novel mind-body management study of IBS'

• Relief: placebo pills59%reported adequate relief
• Relief: no pills35%reported adequate relief
• Symptom drop vs no pills2×92 vs 46 points

Open-label placebo: 59% reported adequate relief vs 35% with no pills, after 3 weeks

Comparable to IBS drug trials.

More to know, from our read of the paper:

• Small (n=80), short (3 weeks), single-centre: the authors themselves call it a 'proof-of-principle' pilot study
• All outcomes were self-reported symptom scales; patients could not be blinded, so report bias ('wishing to please the experimenter') cannot be eliminated (stated by the authors)
• Placebo patients were told the pills had been 'shown in rigorous clinical testing to produce significant mind-body self-healing processes': a persuasive, positive framing; the result is placebo + rationale, not a pill alone
• Comparison was no treatment (not a hidden/double-blind placebo), so it cannot say open-label works as well as a deceptive placebo
• Recruitment ads for a 'novel mind-body' study may have attracted people open to the idea (stated by the authors)

80 adults with IBS, randomized: open-label placebo pills (told plainly they contained nothing) vs no treatment, 3 weeks. Symptoms were self-reported and patients knew their group. A small proof-of-principle trial, not a treatment recommendation.

We read the abstract and the full text of this paper and checked every number on this page against it (18 facts, checked on 2026-10-01). The study design is named above. Cohort and other observational studies are described as linked, not proven. Found an error? Email theis@onestudyaday.com.