Gardaí have said it is possible for mouthwash to trigger a positive roadside breath test.
Some motorists are worried that thoroughly cleaning their teeth could get them arrested.
Supt Eddie Golden from the Roads Policing Bureau says that it does happen from time to time.
He said: "The concentration levels in mouthwash are very minute.
"When you go to the station and go through the more rigorous controls that we have, that measurement would see how much alcohol is in your system and at that stage, if it's just mouthwash on its own, I'm very confident it wouldn't register on our system."