What happens if people start drinking mouthwash as surrogate alcohol? A quantitative risk assessment

Mouthwash ingestion has been observed in settings of restricted availability to alcoholic beverages such as in hospitals, prisons or military establishments. The literature offers limited evidence that ingredients of mouthwash may have health effects above the effects of ethanol. This study provides a quantitative risk assessment based on analysis of 30 mouthwash samples. All investigated brands contained alcohol, most of them menthol (93%), eucalyptol (90%), benzoic acid (87%), methyl salicylate (67%), and thymol (30%). For low risk drinking scenarios with average levels, only ethanol will exceed acceptable daily intakes (ADI). In worst case scenarios for alcohol dependent consumers ingesting 100 g ethanol per day in the form of mouthwash, methyl salicylate will also exceeded the ADI by a factor of 17. The margin of exposure (MOE) for methyl salicylate, benzoates and thymol was below 100 for average scenarios, and below 10 for worst case scenarios, but ethanol is still the most toxic ingredient with MOE below 1. The occasional or even chronic ingestion of mouthwash may not cause health effects except the effects of ethanol alone. Only in extreme exposures, ingredients such as thymol or methyl salicylate could exacerbate the effects of ethanol, especially by contributing to metabolic acidosis.

Highlights► Mouthwash may be ingested as surrogate alcohol when other alcoholic beverages are unavailable. ► Besides alcohol (ethanol), mouthwashes regularly contain benzoic acid, methyl salicylate, thymol, eucalyptol and menthol. ► Acceptable daily intake levels of these compounds may be exceeded in heavy and dependent drinking scenarios. ► Besides ethanol, methyl salicylate and thymol were found to have the lowest margin of exposure. ► The alcoholic strength of mouthwashes should be labeled.