side effect

noun

: 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.
Recent Examples on the Web Sadly, that’s not all the side effects she’s been dealing with. Sara Vallone, Miami Herald, 11 Apr. 2024 But these ingredients come with a range of side effects, with the most notable being a hangover effect the next day. Carly Weeks, TIME, 10 Apr. 2024 Zendaya is revealing how one of her most influential Dune: Part Two red carpet looks actually came with some pretty serious side effects. EW.com, 9 Apr. 2024 The most common potential side effects of Winrevair include a low platelet count, bleeding, and telangiectasis (red-colored veins appearing on the face). Nick Blackmer, Verywell Health, 8 Apr. 2024 Except the side effects for cicadas, a flying pest, are quite deadly. USA TODAY, 4 Apr. 2024 Possible side effects of omega-3 supplements include bad breath, heartburn, nausea, diarrhea, headaches, smelly sweat, and an unpleasant taste in the mouth. Isabel Vasquez, Rd, Ldn, Parents, 4 Apr. 2024 Common side effects include headaches, dizziness, flushing, nasal congestion, and indigestion. Amber Smith, Discover Magazine, 3 Apr. 2024 The side effects in question included mood swings and depression, both of which are frequently experienced by women on birth control. Katherine J. Wu, The Atlantic, 3 Apr. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'side effect.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1814, in the meaning defined above

Time Traveler
The first known use of side effect was in 1814

Dictionary Entries Near side effect

Cite this Entry

“Side effect.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/side%20effect. Accessed 19 Apr. 2024.

Kids Definition

side effect

noun
: an often harmful and unwanted effect (as of a drug) that occurs along with the basic desired effect
the environmental side effects of using chemicals to kill pests

Medical Definition

side effect

noun
: 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

Last Updated: - Updated example sentences
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