Today someone asked if mouthwash can affect the results of a breathalyzer and, if so, how. Since it’s not the first time that someone has asked this question, I thought that it would be a good idea to address the issue of whether mouthwash can affect a breathalyzer.
A breathalyzer is intended to analyze only the air which comes from deep within a suspected drunk driver’s lungs. The air that comes from the lungs is called alveolar air and any alcohol in alveolar air is related to the concentration of the alcohol in the blood. As the alveolar air passes from the lungs, through the mouth, and into the breathalyzer mouthpiece it can pick up residual alcohol that may be located in the mouth. This alcohol is called “mouth alcohol” and is not necessarily related to the consumption of alcohol or how intoxicated someone might be. Yet, mouth alcohol can cause a breathalyzer to produce an erroneously high blood alcohol reading.
So what causes mouth alcohol?
Mouth alcohol can be cause by many things. Cough drops containing menthol can get stuck in the teeth and cause an elevated BAC reading. Breathalyzers can detect alcohol that may be trapped in the small crevices of dental work or mouth piercings. Belching, vomiting, smoking, and chewing gum can cause vapors of alcohol located in the stomach to rise into the mouth. And yes, mouthwash can linger in the mouth after it is gargled and it, too, is mouth alcohol.
Although none of the above mentioned causes of mouth alcohol leads to intoxication, all of them can cause a false-positive BAC reading on a breathalyzer.
The answer is “yes.” Mouthwash, along with a number of other things, can cause a breathalyzer to produce an incorrect blood alcohol reading which, in turn, can cause a person to be falsely arrested for DUI.