The effectiveness of mouthwash against SARS-CoV-2 infection: A review of scientific and clinical evidence

The COVID-19 pandemic, caused by the spread of SARS-CoV-2 infection that is mainly through the airborne transmission, is a worldwide health concern. This review seeks to assess the potential effectiveness of mouthwash in reducing the oropharyngeal load of SARS-CoV-2 based on the available evidence. Articles related to mouthwash and COVID-19 in PubMed were electronically searched in July, 2021. After manually excluding articles lacking sufficient scientific evidence or validation processes, those with inaccessible online full text, those that did not test the effectiveness of mouthwash against SARS-CoV-2, and those not written in English, 17 original and 13 review articles were chosen for this review. The eligible articles revealed that the main virucidal mechanism of mouthwash was via interactions with the viral envelope. Povidone-iodine (PVP-I), cetylpyridinium chloride (CPC), and essential oils with ethanol showed virucidal effects on SARS-CoV-2 in vitro, potentially by interfering with the viral envelope. A few clinical studies demonstrated that PVP-I, CPC, hydrogen peroxide, and chlorhexidine reduced the oropharyngeal load of SARS-CoV-2. Although the available evidence is limited, mouthwash containing PVP-I or CPC shows potential for reducing the oropharyngeal load of SARS-CoV-2 and thus may present a risk-mitigation strategy for COVID-19 patients.