What are the effects of mouthwash on an alcohol test result?

The vast majority of mouthwash products contain a small percentage of alcohol. If a subject consumes an alcohol-based mouthwash prior to a breath or saliva alcohol test, the remnants of the alcohol from the mouthwash will contaminate the alcohol test result. Breath or saliva alcohol testing devices will pick up and register the alcohol molecules that remain in the mouth shortly after mouthwash use. The residual effect of mouth alcohol is known as “residual mouth alcohol” and it lasts no more than 10 to 15 minutes.

In the case of DOT testing, all alcohol screening tests with results of .020 or greater are considered to be positive test results. When the screening test result is positive, the DOT requires the technician to administer a second test, called the confirmation test. The confirmation test is conducted after an observed 15 minute wait period and the results of that test are considered to be final test results. During the observed 15 minute wait period all mouth alcohol molecules from the mouthwash will dissipate before the start of the confirmation test. If the test result of the confirmation test is .020 or greater, the technician can rest assured the result is due to consumed alcohol in the body and not mouth alcohol.