Listerine® Products: An Update on the Efficacy and Safety

UNLABELLED: In the 19th century, the mouthwash Listerine® was formulated from four essential oils. Later, the oils were replaced by their marker substances. To keep them in solution, 24-27% ethanol was added as a vehicle. This is an update of our previous review on the efficacy and safety of Listerine®. METHOD: PubMed was searched for clinical studies on the therapeutic benefits and safety of Listerine® from the end of 2011 to the end of October 2015. RESULTS: Sixteen studies were found and extracted. Three of the four 6-month studies were of sound confirmatory design. Two of these investigated Listerine® and one Listerine Zero®. The evidence of effectiveness for Listerine®, based on the bulk of three confirmatory studies and numerous exploratory studies carried out so far, is strong, but only moderate for Listerine® Zero and poor for Listerine® Cool Blue. In the three safety studies identified, we found methodological flaws that biased the results. CONCLUSIONS: Evidence is accumulating that Listerine® is effective in improving oral health, but the absence of systematic toxicological studies means that an accurate safety assessment cannot be made.