UMEM Educational Pearls

Category: Toxicology

Title: Officer, I'm not drunk. I just used a mouth wash!

Keywords: ethanol, breath analyzer, mouth wash (PubMed Search)

Posted: 9/12/2019 by Hong Kim, MD, MPH
Click here to contact Hong Kim, MD, MPH


Breath analyzers are commonly used by law enforcment officers to test for alcohol intoxication. Breath analyzer uses ethanol partition ratio between blood:breath of 1:2100 = 1 gm of ethanol in 2100 mL of breath/air.

Mouth wash products are frequently used for oral hygiene, and at times, to "mask" odor of substances. These products are readily available in any grocery stores or pharmacy and contain upto 26.9% ethanol (e.g. Listerine) (18.9% - Scope; 14.0% - Cepacol).  

Recently, a small study using healthy volunteers (n=11) was published to investigate the impact of limited ethanol exposure (mouth wash and ethanol vapor) on the breath-alcohol concentration (BrAC).



  1. Ethanol vapor exposure (856 mg/m3) for 15 minute. 
  2. Oral rinse (for 30 sec) using mouth wash containing 22% ethanol, 1 hour after the ethanol vapor exposure
  3. Blood and breath samples were collected before, between and after exposure.



Blood: No or very low levels of ethanol (0.002 mg/g) were detected in blood at all collection time for both exposures.

BrAC - first collection -- seconds after exposure

  • Ethanol vapor: 0.14 mg/L (0.014 mg/dL)
  • Mouth wash: 4.4 mg/L (0.44 mg/dL)


Mean time to negative BrAC level (Swedish statutory limit of 0.1 mg/L = 0.01 mg/dL in air) (FYI: US limit = 80 mg/dL)

  • Ethanol vapor: 0.5 min (0.06 - 0.7 min)
  • Mouth wash: 11 min (6 - 15 min) 



  • Ethanol vapor did not affect the BrAC
  • Mouth wash use can transiently increase BrAC; however, their use does not sufficiently increase the BrAC to result in "false positive" based upon US limit.


Ernstgard L et al. Washout kinetics of ethanol from the airways following inhalation of ethnaol vapors and use of mouthwash. Clin Toxicol. 2019 Jun 19:1-7. doi: 10.1080/15563650.2019.1626868. [Epub ahead of print]