Is it always unethical to use a placebo in a clinical trial?

PLoS Med. 2005 Mar;2(3):e72. doi: 10.1371/journal.pmed.0020072. Epub 2005 Mar 29.


Placebos are used in trials to conceal whether a treatment is being given or not and hence to control for the psychosomatic effects of offering treatment. Placebo-controlled trials are controversial. Critics of such trials argue that if a proven effective therapy exists, a placebo should not be used. But proponents argue that placebo trials are still crucial to prove the efficacy and safety of many treatments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ethics, Medical
  • Humans
  • Placebos*
  • Randomized Controlled Trials as Topic / ethics*


  • Placebos