side effect
Americannoun
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side effects
plural
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any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.
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any accompanying or consequential and usually detrimental effect.
the side effects of air pollution.
noun
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any unwanted nontherapeutic effect caused by a drug Compare aftereffect
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any secondary effect, esp an undesirable one
Other Word Forms
Noun Inflected Forms
Etymology
Origin of side effect
First recorded in 1880–85
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Even beyond the black market, the glamorization of testosterone often glosses over the primary, life-altering side effect: reduced fertility.
From Slate ● Sep. 13, 2026
A well-documented side effect of the drugs is called dysgeusia, which can produce an unpleasant, metallic taste in the mouth.
From The Wall Street Journal ● Aug. 19, 2026
That’s an inevitable side effect of appearing on a Bill Lawrence show.
From Los Angeles Times ● Aug. 10, 2026
The findings suggest that genetic instability may not simply be a side effect of cancer.
From Science Daily ● Aug. 2, 2026
“Nostalgia is a side effect of cancer,” I told him.
From "The Fault in Our Stars" by John Green
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
