side effect

American  

Or side-effect

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.

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side effect British  

noun

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

2. any secondary effect, esp an undesirable one

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Etymology

Origin of side effect

First recorded in 1880–85

Example Sentences

"Weight-loss drugs are powerful medicines and can have serious side effects, which is why they must only be prescribed by an appropriately trained healthcare professional."

From BBC

The panels have had another surprising side effect: because the grass is shielded from the elements, it's of more consistent quality.

From Barron's

Last week, the chair of the MPs' Health Select Committee asked the UK drug regulator to review warnings about these side effects, and the government called our latest findings "hugely concerning".

From BBC

"Some of the side effects of weight-loss injections, like nausea and vomiting, could also be very triggering to someone who has an existing eating disorder," she said.

From BBC

After the operation, participants are closely observed for 12-15 months to track changes in symptoms and watch for potential side effects, including dyskinesia -- excess movements -- or infection.

From Science Daily

Related Words

• aftereffect
• reaction