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

British Dental Journal (2025)Cite this article

Abstract

Aim Antimicrobial resistance is an emerging global health challenge, driven largely by the overuse of antimicrobial drugs. However, the extent of mouthwash-induced antimicrobial resistance remains poorly understood. This systematic review aimed to assess the influence of commonly used mouthwashes on antimicrobial resistance, focusing on resistance genes, microbial alterations, and cross-resistance to antibiotics.

Methods PubMed, Scopus, Web of Science, and grey literature, including Google Scholar, were searched for studies evaluating mouthwash-induced antimicrobial resistance. The search strategy included terms related to ‘oral microbiome', ‘mouthwash' and ‘antimicrobial resistance', with Boolean operators tailored to each database. Risk of bias was assessed using In Vitro Critical Appraisal Tool for in vitro studies and the Modified Joanna Briggs Institute for ex vivo and in vivo studies, respectively.

Results Twelve studies were analysed, comprising seven in vitro, four ex vivo and one in vivo study. A total of 91 patients and 213 bacterial isolates were assessed across various mouthwashes, including chlorhexidine digluconate, cetylpyridinium chloride, hydrogen peroxide and others. Due to heterogeneous outcomes, a meta-analysis was not conducted. The findings consistently revealed increased minimum inhibitory concentrations of oral bacteria and the presence of resistance genes, highlighting a potential rise in antimicrobial resistance.

Conclusion This systematic review indicates a possible association between mouthwash use and resistance-related changes in the oral microbiome; however, the limited and heterogeneous evidence base warrants cautious interpretation. Further, longitudinal research is needed to elucidate the underlying mechanisms and inform evidence-based guidelines for mouthwash use.

Key points

  • This review consolidates evidence that frequent or prolonged use of antiseptic mouthwashes, especially chlorhexidine, can foster resistance traits in oral bacteria marked by increased MICs and resistance gene amplification.

  • The findings support a more judicious, individualised approach to mouthwash prescribing, discouraging routine, unsupervised use, and reinforcing the importance of antimicrobial stewardship in dental practice.

  • Highlights the need to revisit current guidelines on antiseptic mouthwash use and advocates for clearer regulatory policies addressing over-the-counter availability and labelling in the context of antimicrobial resistance.

  • Stresses the critical need for high-quality, long-term human studies to validate in vitro findings and to explore mechanisms of resistance and cross-resistance in clinical settings.

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Data availability

All data generated or analysed during this systematic review are included in this published article and its supplementary materials. The extracted data tables, search strategies, and risk of bias assessments are available upon request from the corresponding author. No new datasets were generated for this study.

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Authors and Affiliations

  1. Resident Doctor, Department of Periodontia and Community Dentistry, Dr Ziauddin Ahmad Dental College, AMU, Aligarh, India

    Ahmad Shoeb Hashmi

  2. Professor, Department of Periodontia and Community Dentistry, Dr Ziauddin Ahmad Dental College, AMU, Aligarh, India

    N.D. Gupta & Neha Agrawal

  3. Assistant Professor, Department of Periodontia and Community Dentistry, Dr Ziauddin Ahmad Dental College, AMU, Aligarh, India

    Saif Khan & Syed Amaan Ali

  4. Assistant Professor, Department of Paediatrics and Preventive Dentistry, Dr Ziauddin Ahmad Dental College, AMU, Aligarh, India

    Mohammad Atif

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Contributions

ASH: conceptualisation, data screening and extraction, manuscript drafting. NDG: supervision, risk of bias assessment, critical review. SK: data screening and extraction., data interpretation. NA: risk of bias assessment, data interpretation. SAA: data screening and extraction, manuscript editing. MA: data screening and extraction, manuscript writing.

Corresponding author

Correspondence to Syed Amaan Ali.

Ethics declarations

The authors declare no conflicts of interest related to this study. Ethical approval and consent was not required for this study, as it is a systematic review of previously published data.

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Hashmi, A., Gupta, N., Khan, S. et al. Evaluation of mouthwash-induced antimicrobial resistance in the oral microbiome: a systematic review. Br Dent J (2025). https://doi.org/10.1038/s41415-025-9012-9

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