The placebo effect
Henry BeecherAsbjørn HróbjartssonTed Kaptchuk
This page delivers no verdict; it presents claims and evidence with their sources. No theory in science is absolute. Method
For everyone
A pill without active ingredient or a sham treatment can be associated with reduced symptoms in some patients; this is called the placebo effect. It is the main reason new treatments are tested against placebo. How strong the placebo effect is remains disputed; part of it can be explained by natural recovery and measurement biases.
For specialists
Beecher (1955) reported that about 35% of patients across several studies responded to placebo; the analysis was criticised for not separating natural recovery and regression to the mean. Hróbjartsson and Gøtzsche (2001) examined trials comparing placebo with no treatment and found no significant effect on objective outcomes and a small effect on subjective outcomes such as pain. Kaptchuk et al. (2010) reported symptom improvement in irritable bowel syndrome even when patients were told openly that they were receiving placebo.
Claims
- An inert treatment can produce real, measurable improvement through the patient's expectation.[1]
Evidence
Supporting
Irritable bowel syndrome patients who knew they were taking placebo had significantly fewer symptoms than an untreated group.[3]
Challenging
An analysis of 114 trials comparing placebo with no treatment found no significant effect of placebo on objective and binary outcomes.[2]
Connections
Sources
- Article (1955). The powerful placebo. JAMA 159(17), 1602–1606DOI 10.1001/jama.1955.02960340022006archive
- Article (2001). Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment. New England Journal of Medicine 344, 1594–1602DOI 10.1056/NEJM200105243442106archive
- Article (2010). Placebos without deception: a randomized controlled trial in irritable bowel syndrome. PLoS ONE 5(12), e15591DOI 10.1371/journal.pone.0015591archive
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Cite this page
Athena contributors. (2026). The placebo effect. Athena: The tree of human knowledge. Retrieved November 1, 2026, from https://latifkedi.github.io/athena/en/d/plasebo/
@misc{athena_plasebo,
title = {The placebo effect},
author = {{Athena contributors}},
year = {2026},
howpublished = {\url{https://latifkedi.github.io/athena/en/d/plasebo/}},
note = {Athena: The tree of human knowledge. Accessed: 2026-11-01}
}Added: September 27, 2026 · Last changed: September 27, 2026 · Page history