Alcohol-based mouthwash can have a huge negative effect on your Breathalyzer test. Mouthwash can produce insanely high Breathalyzer test results. This video demonstrates how Listerine caused me to blow over a .73 while stone-cold sober:
That is nine times the legal limit!
Using mouthwash can cause you to fail an ignition interlock test more than 10 minutes after using it. And the effects of using mouthwash is can be measured by a breathalyzer more than 20 minutes after using mouthwash.
If you have an ignition interlock avoid using alcohol-based mouthwash. And if you have had any mouthwash or alcohol in your mouth within the last 30 minutes don’t take a Breathalyzer test.