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 some people, treating acne is enough of a benefit to push through the side effects of using a topical retinoid, for instance. Sarah Jacoby, SELF, "Here’s How to Build Your Tolerance to Irritating Skin-Care Products," 26 Mar. 2019 Large fiscal deficits had the side effect of enabling businesses and consumers to purchase more goods from abroad, driving down overall U.S. saving and driving up the trade imbalance. ... Josh Zumbrun, WSJ, "Why Trump’s Effort to Narrow the Trade Gap Has Flopped So Far," 2 Mar. 2019 They're typically used by athletes for endurance training, but the keto-friendly ones claim to energize you and offset the physical side effects of the keto flu. Jaclyn London, Ms, Rd, Cdn, Good Housekeeping, "Keto Diet Pills and Supplements May Hurt Your Health and Waste Your Money," 16 Jan. 2019 In addition to being time prohibitive for a new mom, there are also potential side effects, including headaches, dizziness, excessive sleepiness, and sudden loss of consciousness. Lauren Valenti, Vogue, "The FDA Has Approved the First Postpartum Depression Drug—And It’s a Game-Changer," 20 Mar. 2019 Those principles were crafted to avoid missteps in developing new technology that could have harmful side effects. Douglas Macmillan, WSJ, "Microsoft Pushes Urgency of Regulating Facial-Recognition Technology," 6 Dec. 2018 Mood stabilizers may also cause more serious side effects. Korin Miller, SELF, "5 Bipolar Disorder Treatments You Should Know About," 30 Nov. 2018 Ebner found the treatment itself to be an easy process that only took a few minutes each day and had minimal side effects. The Seattle Times, "Protecting this mom’s heart from radiation," 15 Oct. 2018 The number of migrants going to Algeria may be 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. Lori Hinnant, The Seattle Times, "Algeria abandons thousands of migrants in 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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Statistics for side effect

Last Updated

11 Apr 2019

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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

Comments on side effect

What made you want to look up side effect? Please tell us where you read or heard it (including the quote, if possible).


an act or instance of returning to life

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