Meaning & use
adverse effect
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Meanings
nouncountable
An unwanted and harmful result of something, especially a medicine or treatment, that happens besides the result that was intended.
Grammar: Usually followed by of or on: adverse effects of the drug, adverse effects on health.
Patterns
- the adverse effect of something
- an adverse effect on someone or something
The leaflet lists dizziness as a possible adverse effect of the tablets.
Researchers found no adverse effect on the children who joined the trial.
Several workers reported adverse effects after the new cleaning chemical was introduced.
nouncountableformal
A damaging consequence of a decision, policy or event for a person, business or environment.
Grammar: Often used in the plural for broader consequences: adverse effects on trade.
Patterns
- an adverse effect on something
Rising fuel costs had an adverse effect on small delivery firms.
The drought is likely to have an adverse effect on this year's harvest.
Critics warned of the adverse effects the new tax would have on young families.
Word forms
| plural | adverse effects |
|---|
Common combinations
- cause an adverse effect
- Mixing these two medicines can cause an adverse effect.
- report an adverse effect
- Patients should report any adverse effect to their doctor.
- serious adverse effect
- A serious adverse effect led the company to stop the trial.
- have an adverse effect on
- Lack of sleep can have an adverse effect on your memory.
- potential adverse effects
- The pharmacist explained the potential adverse effects of the new prescription.
Synonyms and how they differ
- side effect
- A side effect is any secondary result of a drug, harmful or not, so it is broader and more casual than adverse effect.
- negative consequence
- This phrase is more general and can describe any bad outcome, not specifically a medical reaction.
- drawback
- A drawback is a disadvantage of a plan or product, and it sounds milder than the harm implied by adverse effect.
- harmful effect
- This is the plain-English version, with a less technical tone than adverse effect.
Opposites
Word family
Commonly confused: adverse effect or averse? adverse effect or adverse affect?
adverse effect vs averse
Averse means strongly unwilling or opposed, as in 'not averse to a challenge', and is not a synonym of adverse.
adverse effect vs adverse affect
This is a common misspelling. Effect is the noun for a result, while affect is normally a verb.
Practice
The doctor warned that the drug could have an adverse ___ on her kidneys.
Choose one answer.
After the adjective adverse and the article an, a noun is needed, and the noun meaning result is effect. Affect is normally a verb.
Make it your own
Write a sentence using “adverse effect”, then check it and compare it with the examples above.