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 Also, given the medicine isn’t designed to help with fertility and pregnancy, there could be harmful side effects. Dominique Fluker, Essence, 25 Oct. 2024 Based on research to date, creatine monohydrate is safe and well-tolerated, with minimal side effects in healthy people. Jennifer Lefton, Ms, Rd/n, Cnsc, Fand, Verywell Health, 24 Oct. 2024 What are the side effects of the antidepressant drug Duloxetine? Chris Sims, The Courier-Journal, 24 Oct. 2024 Like with any immunization, though, there can be side effects. Beth Ann Mayer, Parents, 24 Oct. 2024 See all Example Sentences for side effect 

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 2 Nov. 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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