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
Many people undergoing chemotherapy experience a frustrating side effect often called "chemo brain."
From Science Daily • Jun. 10, 2026
Tech Trader first began discussing the looming memory chip shortage back in December, as one more side effect of the booming market for artificial intelligence.
From Barron's • May 29, 2026
And other topics we delve into include the growing divide in jury rooms, a side effect of weight-loss drugs and who’s helping young adults buy a first home.
From The Wall Street Journal • May 23, 2026
I was a painfully shy, awkward kid, with low self-esteem and almost no social skills—a side effect of spending most of my childhood inside the OASIS.
From "Ready Player One: A Novel" by Ernest Cline
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.
