side effect
Americannoun
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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.
A side effect of that is a lack of empathy and curiosity.
From Los Angeles Times • Jul. 1, 2026
It’s one more side effect of the booming market for artificial intelligence.
From Barron's • Jun. 1, 2026
About 44% of users in the study mentioned at least one side effect, most commonly gastrointestinal problems.
From Science Daily • May 24, 2026
Dandruff is a side effect of my medications, so I now use the same Head & Shoulders conditioner as my dad, which doesn’t help the middle-aged-man concern.
From Slate • May 23, 2026
I open my mouth just like they did, hoping they’ll think my trembling is a side effect of just coming out of stasis.
From "The Last Cuentista" by Donna Barba Higuera
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.
