placebo effect

American  

[pluh-see-boh] / pləˈsi boʊ /

noun

1. a reaction to a placebo manifested by a lessening of symptoms or the production of anticipated side effects.

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placebo effect British  

noun

1. med a positive therapeutic effect claimed by a patient after receiving a placebo believed by him to be an active drug See control group

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Etymology

Origin of placebo effect

First recorded in 1945–50

Example Sentences

The other half received a sham treatment designed to control for the placebo effect.

From Science Daily • May 22, 2026

Only 15% of people with major depression experienced a substantial benefit from taking antidepressants beyond the placebo effect, according to a 2022 study.

From The Wall Street Journal • May 4, 2026

“The placebo effect can also be very powerful, especially for treatments that require significant effort and cost.”

From Los Angeles Times • Sep. 12, 2025

He warned a pineal cyst should only be removed in extremely rare circumstances, and believes the operations' successful results could be explained by the "placebo effect".

From BBC • Dec. 4, 2024

It must have been a placebo effect, but it was a great placebo effect.

From "It’s Kind of a Funny Story" by Ned Vizzini