Grammar fix
an adverse effect
unfavourable effect (formal/neutral)
a negative or harmful result caused by something, especially used in formal or technical contexts such as health, policy, or science.
Hear it in context
Notice where the phrase sounds natural.
- The new medication had an adverse effect on some patients, causing headaches and nausea.health
- While technology has brought many benefits, it can also have an adverse effect on young people's attention spans if not used responsibly.IELTS speaking
Fix the pattern
Pattern: have/cause/produce/lead to an adverse effect (on something)
WrongI'm not adverse to the idea.
RightI'm not averse to the idea.
'Averse' = reluctant; 'adverse' = harmful. Don't mix them up.
Patternhave/cause/produce/lead to an adverse effect (on something)
Use it right
Choose the version that sounds natural in speech.
'Engender deleterious effects' is medical-formal; in speech people say 'side effects'.
Build natural chunks
Words that usually travel with it.
an adverse effect ononhaveanyserious
Don't confuse it
'Adverse effect' is more formal and specific than 'bad effect' or 'negative effect', and is often used in contexts like health, policy, or scientific reports. It does not mean 'opposite effect' (which would be 'contrary effect').