side effect
Americannoun
-
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.
-
any accompanying or consequential and usually detrimental effect.
the side effects of air pollution.
noun
-
any unwanted nontherapeutic effect caused by a drug Compare aftereffect
-
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
Tracker funds will have to triple their holdings in two weeks as a side effect of the new accelerated-entry rules.
From The Wall Street Journal ● Jun. 14, 2026
Many people undergoing chemotherapy experience a frustrating side effect often called "chemo brain."
From Science Daily ● Jun. 10, 2026
It’s one more side effect of the booming market for artificial intelligence.
From Barron's ● Jun. 1, 2026
It’s a side effect of your magical medical cocktail.
From "Challenger Deep" by Neal Shusterman
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.
