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Will mouthwash interfere with the results of a breath alcohol test?
10-01-2010

 

If a subject has anything in their mouth containing alcohol immediately prior to a breath alcohol test the remnants of the alcohol will contaminate the test results. However, the residual effects of mouth alcohol are gone in 10 to 15 minutes.

There are two ways to handle the mouth alcohol question when doing alcohol testing.

  • Observe every subject for 10 to 15 minutes prior to testing to ensure they have not had anything in their mouth.  Law enforcement agencies frequently use this method.
  • Conduct the alcohol test without any prior observation of the subject.  If the test result is positive, observe the subject for 10 to 15 minutes to ensure they do not put anything in their mouth, and conduct the test again.  If the initial positive test was due only to mouth alcohol the second test will be zero.  If the initial positive test was truly due to the subject’s intoxication, the result of the second test will be similar to the initial test.