side effect


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

For environmental campaigners, this is a welcome side effect. Umair Irfan, Vox, "A major anti-fracking ballot measure in Colorado has failed," 7 Nov. 2018 Researchers have not done further analysis to determine if the child had died of malaria, but evidence of an abscessed tooth, a side effect of the disease, suggested that was the case. Kristine Phillips, The Seattle Times, "Archaeologists find ‘vampire burial’ site of a child feared capable of rising from the dead," 26 Oct. 2018 In fact, management experts and executives say, harassment can be a direct side effect of a workplace that slights women on everything from pay to promotions, especially when the perception is that men run the show and women can’t speak up. Vanessa Fuhrmans, WSJ, "What #MeToo Has to Do With the Workplace Gender Gap," 23 Oct. 2018 Gomez reportedly visited the hospital twice in recent weeks due to a low white blood cell count, which was likely a side effect from her recent kidney transplant. D. Elizabeth, Glamour, "Selena Gomez Is Reportedly Seeking Treatment Following an 'Emotional Breakdown'," 11 Oct. 2018 Unfortunately, sweating is a common side effect of anxiety disorders, according to the NIMH. Cassie Shortsleeve, SELF, "10 Physical Symptoms of Anxiety, Because It’s Not All Mental," 6 Oct. 2018 Toby's outburst may have been a side effect of him getting off his antidepressants. Eileen Reslen, Good Housekeeping, "The Important Things You Missed During 'This Is Us' Last Night," 3 Oct. 2018 Dysgeusia is a common side effect of chemotherapy and makes food and drinks taste bitter or bland. Caroline Judelson, Fox News, "Czech beer brewed to aid cancer patients with loss of taste, appetite," 10 July 2018 Please sit down before viewing, because falling over is a side effect of getting up close and personal with the star of our solar system. Shannon Stirone, WIRED, "Space Photos of the Week: Scientists Are Seeing Red Over Jupiter’s Spot," 30 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

5 Dec 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


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


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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More from Merriam-Webster on side effect

Rhyming Dictionary: Words that rhyme with side effect

Spanish Central: Translation of side effect

Nglish: Translation of side effect for Spanish Speakers

Britannica English: Translation of side effect for Arabic Speakers Encyclopedia article about side effect

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to enclose within walls

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