The oral mucosa is a mechanical barrier that has selective permeability, allowing some substances to enter the body but which excludes others.1 There have been concerns raised over the effect of ethanol on the oral mucosa,2 potentially increasing permeability.3

A study by Bhageerutty et al. demonstrated that due to the short alcohol-exposure times (consistent with daily mouth rinse use), LISTERINE® did not alter the permeability of the oral mucosa, leading the authors to conclude: “These results suggest that under conditions of actual use, alcohol-containing mouth rinse is unlikely to alter the permeability barrier properties of oral mucosa to water-soluble compounds”4

A separate study by Moharamzadeh, published in 2009 investigated the biological effect of three different alcohol-containing mouth rinses on the oral mucosa. The controls were triethylene glycol dimethacrylate as a positive control and two negative controls (phosphate buffered saline [PBS] or cola).2

Histologic appearance of oral mucosa models following exposure to test materials2



As can be seen, triethylene glycol dimethacrylate (the positive control) resulted in the epithelium being severely disrupted and separated from the connective tissue layer. No significant damage to the oral mucosa models was observed after exposure to the three alcohol-containing mouth rinses, or the negative controls. The study concluded that alcohol-containing mouth rinses do not cause significant cytotoxic damage.2


A study on the oral mucosa by Moharamzadeh in 2009 concluded that alcohol-containing mouth rinses do not cause significant cytotoxic damage.1


This study aimed to detect cytological changes in the oral mucosa after using an alcohol-containing mouth rinse (LISTERINE®).


The study found no statistical difference in cytology between the groups at baseline (p>0.05). There was no clinical mucosal alteration observed after using the mouth rinse at the end of the study in either group. When analysing the cytological differences between both groups at the end of the study (6 months of using mouth rinses) there was no statistically significant difference (see table).1


  1. Markopoulos AK. A Handbook of Oral Physiology and Oral Biology. Bentham Books, 2010.
  2. Moharamzadeh K et al. Biologic assessment of antiseptic mouthwashes using a three dimensional human oral mucosal model. J Periodontol 2009; 80: 769–775.
  3. Squier CA et al. Enhanced penetration of nitrosonornicotine across oral mucosa in the presence of ethanol. J Oral Pathol 1986; 15(5): 276–279.
  4. Bhageerutty Y et al. Effect of an alcohol-containing mouthwash on mucosal permeability. J Dent Res 1998; 77(IADR Abstracts): 1091.