nocebo effect

noun

: the development of adverse side effects or worsening in the condition of a patient that occurs in response to medical treatment but cannot be considered due to the specific treatment used

With a nocebo effect, if test subjects believe there may be side effects, they often experience them. Again, expectations shape reality.

—Sanjay Gupta

Examples of nocebo effect in a Sentence

Recent Examples on the Web

That’s the nocebo effect—the evil twin of the placebo. —David Meade, Forbes.com, 18 July 2025

The nocebo effect is another important aspect of mindset. —Jennifer C. Lovejoy, Scientific American, 7 Dec. 2022

Marino, who watched the video, told the San Diego Union-Tribune a nocebo effect could explain Faiivae's reaction since his symptoms did not suggest an overdose. —Miriam Fauzia, USA TODAY, 25 Aug. 2021

The placebo effect also has a shadowy twin: the nocebo effect. —Carl Engelking, Discover Magazine, 5 Oct. 2017

Word History

First Known Use

1969, in the meaning defined above

Rhymes for nocebo effect

• affect
• aspect
• bedecked
• bisect
• collect
• connect
• correct
• deflect
• detect
• direct
• dissect
• eject

Medical Definition

nocebo effect

noun

: the development of adverse side effects or worsening in the condition of a patient that occurs in response to medical treatment but cannot be considered due to the specific treatment used

With a nocebo effect, if test subjects believe there may be side effects, they often experience them. Again, expectations shape reality.

—Sanjay Gupta, Chasing Life: New Discoveries In The Search For Immortality …

The placebo effect has an evil twin: the nocebo effect, in which dummy pills and negative expectations can produce harmful effects.

—Helen Pilcher, New Scientist