Evaluation of mouthwash-induced antimicrobial resistance in the oral microbiome: a systematic review

This systematic review examined whether common mouthwashes contribute to antimicrobial resistance (AMR). Across 12 studies—spanning in vitro, ex vivo, and one in vivo study—the authors found indications that certain mouthwashes, such as chlorhexidine, cetylpyridinium chloride, and hydrogen peroxide, may increase bacterial tolerance, raise minimum inhibitory concentrations, and promote the presence of resistance genes in oral bacteria. Although these findings suggest that mouthwash use could influence resistance development in the oral microbiome, the available evidence is limited, highly variable, and insufficient for firm conclusions. The review highlights the need for more robust, long-term research to clarify these potential risks and to guide safe, evidence-based mouthwash use.