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.
First Known Use of side effect
SIDE EFFECT Defined for English Language Learners
Definition of side effect for English Language Learners
: 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
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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