Can't Help Doing vs. Can't Help To Do
Cambridge documents can’t/couldn’t help + -ing for being unable to control or stop an action, and also documents the separate “can’t help but + bare infinitive” pattern. Do not confuse the involuntary-action idiom with ordinary help meaning assist; the latter can take different complement patterns and expresses a different idea.
Use “can’t help doing” when you mean you cannot stop yourself from an action; “can’t help to do” normally belongs, if used, to the separate help = assist sense rather than this idiom.
Key details
Choose the right form
| Meaning / situation | Construction | Decision |
|---|---|---|
| unable to stop or avoid an action | can’t help + -ing | use the idiomatic pattern |
| help = assist in performing an action | help + (to) infinitive | treat as the separate assist sense |
Quick tests
Meaning-of-help test
Does “help” mean that the subject cannot prevent the action?
If yes: Use “can’t help doing.”
If no: If “help” means assist, an infinitive may belong to that separate construction.
Caveat: Do not treat “can’t help to do” as an interchangeable form of the cannot-avoid idiom.
Examples
I can’t help laughing when he tells that story.
The speaker cannot prevent the reaction.
She can’t help worrying about the result.
The idiom takes the -ing form.
I can’t help to laugh when he tells that story.
Better: I can’t help laughing when he tells that story.
For the cannot-avoid meaning, use “can’t help laughing.”
Further guidance
Boundary
Do not confuse the involuntary-action idiom with ordinary help meaning assist; the latter can take different complement patterns and expresses a different idea.
Construction
Cambridge documents can’t/couldn’t help + -ing for being unable to control or stop an action, and also documents the separate “can’t help but + bare infinitive” pattern.
Decision
Use “can’t help doing” when you mean you cannot stop yourself from an action; “can’t help to do” normally belongs, if used, to the separate help = assist sense rather than this idiom.
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.
- can't/couldn't help — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Can't/couldn't help + -ing for being unable to stop oneself from an action, with separate can't help but pattern