Prevent Someone From Doing vs. Prevent Someone To Do
Cambridge grammar states that prevent is not followed by a to-infinitive in this pattern; the action is expressed with from + -ing, and Cambridge also records object + -ing without from in some usage. This guide is about the complement after prevent. It does not rule out a to-infinitive elsewhere in a larger sentence when that infinitive has a different grammatical role.
Use “prevent someone from doing” when you mean stop someone from carrying out an action. “Prevent someone to do” is not the parallel direct-complement construction.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| stop a person from carrying out an action | prevent + person + from + -ing | Use the documented direct prevention pattern. |
| prevent an event/outcome | prevent + noun phrase | A noun object is possible in a different construction. |
| person + to-infinitive as a parallel direct complement | not the standard parallel construction here | Do not substitute “prevent someone to do.” |
Quick tests
Meaning / construction test
Are you naming the action that a person is stopped from carrying out?
If yes: Use “prevent someone from doing something.”
If no: Use another documented “prevent” construction if the complement is a noun/event rather than a person’s action.
Examples
The barrier prevented visitors from entering early.
“From” plus -ing expresses the prevented action.
The new cover helps prevent damage.
A noun object can follow “prevent” in a different construction.
Nothing prevented us from continuing.
The person/object plus “from” + -ing pattern expresses prevention.
Further guidance
Boundary
This guide is about the complement after prevent. It does not rule out a to-infinitive elsewhere in a larger sentence when that infinitive has a different grammatical role.
Construction
Cambridge grammar states that prevent is not followed by a to-infinitive in this pattern; the action is expressed with from + -ing, and Cambridge also records object + -ing without from in some usage.
Decision
Use “prevent someone from doing” when you mean stop someone from carrying out an action. “Prevent someone to do” is not the parallel direct-complement construction.
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.
- Word patterns: prevent (opens in a new tab)Cambridge Dictionary · Grammar guidance for prevent + object + from + -ing and the warning against prevent + to-infinitive in this pattern