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

This approach uses non-opioid drugs to relieve pain before, during, and after surgery while minimizing the risk of side effects and dependency. —Heather Margonari, Discover Magazine, 28 Nov. 2024

In some cases, chelation can cause organ damage and other severe side effects. —Lauren Leffer, Popular Science, 27 Nov. 2024

The company also warned of additional side effects for patients with specific risk factors. —Maia Pandey, Journal Sentinel, 26 Nov. 2024

Obstacles include unexpected side effects of numerous possible bank regulation changes, and uncertainly about changes to tax policy, tariff policy, trade policy, international policy, energy policy, and immigration policy. —Michael Del Castillo, Fortune, 26 Nov. 2024

Word History

First Known Use

1814, in the meaning defined above

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