Harmful To: Standard Pattern
Harmful To: Standard Pattern records a directly documented English construction and keeps guidance bounded to the evidenced pattern rather than turning one attested complement into a universal prohibition.
Use “harmful to” when saying that something causes or can cause harm to a person, thing, system, or environment.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| something causes or can cause harm to a person, thing, system, or environment | harmful to + object | Use “to” before the entity affected. |
| the harmful action itself is expressed as a clause | harmful + clause/other construction | Choose the construction required by the sentence rather than forcing a prepositional phrase. |
Quick tests
Meaning / construction test
Are you directly naming the person or thing that may be harmed?
If yes: Use “harmful to.”
If no: Use the sentence structure required by the different complement.
Caveat: This guide addresses the directly documented “harmful to” pattern; it does not imply that “harmful” must always be followed by “to.”
Examples
Excess moisture can be harmful to the equipment.
“To” introduces the affected thing.
The chemical is harmful to aquatic life.
The affected entity follows “to.”
The report explains why the practice can be harmful.
No “to” phrase is needed when the affected object is not stated there.
Further guidance
Construction
Use “harmful to” when saying that something causes or can cause harm to a person, thing, system, or environment.
Style Boundary
Cambridge directly labels “harmful to someone/something”; this page is limited to that construction and does not generalize other adjective-preposition choices.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- HARMFUL TO SOMEONE/SOMETHING — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct collocation evidence for “harmful to someone/something.”