Yes, it can. Many mouthwashes contain a high amount of alcohol—sometimes up to 27%—and that can trigger a failed Ignition Interlock Device (IID) test.
Ignition Interlock Devices detect any trace of alcohol on your breath. Even if you don’t swallow it, mouthwash can leave alcohol vapors in your mouth for up to 15 minutes after use, which can cause a false positive.
To avoid issues:
- Switch to alcohol-free mouthwash. Most brands offer it, and it’s better for your teeth.
- Rinse with water. If you use alcohol-based mouthwash, rinse thoroughly and wait at least 15 minutes before testing.
- Keep water handy. A quick rinse before every test is a good habit to avoid false readings.
Bottom Line:
Alcohol-based mouthwash can interfere with your IID test results. Either switch to alcohol-free mouthwash or give yourself plenty of time (and water) before testing.
