In a study from 2007, Kerr et al compared the effect of an alcohol-containing mouth rinse and a non-alcohol-containing mouth rinse on salivary flow and symptoms of dry mouth in healthy (non-xerostomic) adults.¹

The observer-blinded, randomised, crossover pilot study involved 20 adults studied for 1 week. LISTERINE^® was compared with a non alcohol-containing mouth rinse, 10 subjects per group. The subject rinsed with 20 ml of mouth rinse for 30 seconds; five minutes later whole salivary flow rates (ml/min) were determined. The subject’s subjective perceived mouth dryness was then ascertained on a 100 mm visual analogue scale (VAS).¹

Mean xerostomia VAS scores after 1 week of mouth rinse use¹

Subjective perceived mouth dryness was ascertained by asking subjects to score on a 100mm visual analog scale (VAS) the "level of dry mouth you are experiencing now" (100 mm represented extreme dry mouth). The scale is a horizontal line and the patient marks on the line the point that they feel represents their perception of their current state.

No significant differences were found between the two mouth rinses in terms of salivary flow rate (p>0.05) or subjective sensations of dry mouth (p>0.05). In this study, the use of an alcohol-containing mouth rinse by non-xerostomic healthy adults did not increase the risk of xerostomia.¹

Another study aimed to compare objective and subjective measures of dry mouth following extended (3 months) daily use of an alcohol-based mouth rinse, LISTERINE® Antiseptic, and a non-alcohol based mouth rinse, Crest® Pro-Health™ Rinse, on a population of healthy adults with ‘normal’ baseline salivary flow rates.²

This was a single site, randomised, observer-blinded, parallel designed study comparing the two mouth rinses to evaluate their impact on unstimulated whole salivary flow rates (primary objective outcome), and on perceived dryness (secondary subjective outcome) following daily use at weeks 4 and 12 versus baseline. Flow rates were measured in ml/min and perceived dryness was measured in millimeters on a visual analog scale (VAS) using a number of validated items and factors generated by the Bluestone Mouthfeel Questionnaire (BMQ). For the primary outcome, non-inferiority between-treatment comparisons (set at a margin of 0.15 ml/min) were made. For the secondary outcome, between-treatment comparisons of the mean BMQ VAS scores were made, with emphasis on item 2 (“my mouth feels dry”) and factor 2 (“cleanliness”). ANCOVA models were used to determine the significance of differences.²

One hundred and sixteen subjects successfully completed this study (n=60 Crest® Pro-Health™, n=56 LISTERINE® Antiseptic). The measures of dry mouth were comparable between the two mouth rinses, as demonstrated by non-inferiority of LISTERINE® versus Crest® Pro-Health™ with respect to salivary flow rates at both 4 and 12 weeks (p<0.001). Additionally, no significant differences between groups in the BMQ measures were observed at 4 or 12 weeks.²

Based on this study, extended daily use of an alcohol-based mouth rinse containing essential oils is no more likely to cause a reduction in salivary flow or perceived dryness than a non-alcohol based CPC mouth rinse.²