side effect

Or side-ef·fect

noun

1. any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.

2. any accompanying or consequential and usually detrimental effect.

   the side effects of air pollution.

side effect

noun

1. any unwanted nontherapeutic effect caused by a drug Compare aftereffect

2. any secondary effect, esp an undesirable one

Word History and Origins

Origin of side effect¹

First recorded in 1880–85

Example Sentences

She needs drugs to stay sane, but their side effects—weight gain, spaciness—damage her social life and career prospects and make her almost long for the release of madness.

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“China will aim merely to curb the undesired side effects of this industrial development model, rather than revamp it,” they said in a note.

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"But for osteoarthritis, the doses are only a small fraction of what we use for cancer, and the treatment targets joints that are positioned away from vital organs, which lowers the likelihood of side effects."

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Critics say this can result in unnecessary treatment and side effects.

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If we can treat targets more specifically, we can reduce unwanted side effects and unravel the full potential of immune modulation in cardiovascular disease.

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Related Words

• aftereffect 
• reaction