side effect

noun

Definition of side effect 

: a secondary and usually adverse effect (as of a drug) toxic side effects

called also side reaction

Examples of side effect in a Sentence

Nausea and diarrhea are the side effects of the drug. the harmful side effects of using chemicals to kill insects The merger created positive side effects for both companies.
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Recent Examples on the Web

But one of the most frustrating is dysgeusia, a side effect which causes food to taste bland, bitter, metallic or simply off, meaning patients can’t lean on their favorite comfort foods when things get rough. Jason Daley, Smithsonian, "This Beer Was Developed For Breast Cancer Patients," 9 July 2018 And on the safety side, Kramer said, fewer than 10 percent of patients reported brain swelling, a common side effect for drugs like BAN2401. Damian Garde, STAT, "Biogen reports positive results with Alzheimer’s drug, reviving hopes for once-failed treatment," 5 July 2018 Spending more than $400 million to address the problem, the water works turned to ozone gas to kill the Crypto; in a happy side effect, the ozone gas also removed unwelcome odors and tastes from our drinking water. Jim Higgins, Milwaukee Journal Sentinel, "Milwaukee loves its rivers and Lake Michigan — and keeps abusing them, too," 3 July 2018 Now, the search engine giant is here to help you with a side effect of the July 4th holiday: Traffic. Southern Living, "Google Knows the Best Time to Beat Traffic This Fourth of July," 3 July 2018 Two patients died relatively soon after treatment — one from worsening of the tumor and the other from complications of a drug given to manage a side effect. Marilynn Marchione, The Seattle Times, "Enemy turned ally: Poliovirus is used to fight brain tumors," 26 June 2018 Two patients died relatively soon after treatment — one from worsening of the tumor and the other from complications of a drug given to manage a side effect. Marilynn Marchione, chicagotribune.com, "Enemy turned ally: How poliovirus is used to fight brain tumors," 26 June 2018 Two patients died relatively soon after treatment — one from worsening of the tumor and the other from complications of a drug given to manage a side effect. Washington Post, "Enemy turned ally: Poliovirus is used to fight brain tumors," 26 June 2018 The number of migrants going to Algeria is increasing as an unintended side effect of Europe's successful blocking of the Libyan crossing, said Camille Le Coz, an analyst at the Migration Policy Institute in Brussels. Fox News, "Algeria abandons 13,000 migrants in the Sahara," 25 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'side effect.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of side effect

1814, in the meaning defined above

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Last Updated

26 Sep 2018

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Time Traveler for side effect

The first known use of side effect was in 1814

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More Definitions for side effect

side effect

noun

English Language Learners Definition of side effect

: an often harmful and unwanted effect of a drug or chemical that occurs along with the desired effect

: a result of an action that is not expected or intended

side effect

noun

Medical Definition of side effect 

: a secondary and usually adverse effect (as of a drug) toxic side effects a side effect of drowsiness caused by antihistamines

called also side reaction

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