Penn State. “Mouthwashes, oral rinses may inactivate human coronaviruses, study finds.” ScienceDaily, 19 October 2020. “Certain oral antiseptics and mouthwashes may have the ability to inactivate human coronaviruses, according to a new study. The results indicate that some of these products might be useful for reducing the viral load, or amount of virus, in the mouth after infection and may help to reduce the spread of SARS-CoV-2, the coronavirus that causes COVID-19.”

• Source – Craig Meyers, Richard Robison, Janice Milici, Samina Alam, David Quillen, David Goldenberg, Rena Kass. Lowering the transmission and spread of human coronavirus [full-text]. Journal of Medical Virology, 2020; DOI: 10.1002/jmv.26514 – “Our results suggest that several nasal/sinus and oral rinses had potent virucidal properties and could have the potential to inactivate HCoV and decrease viral load in vivo. Studies of chronic rhinosinusitis have shown the safe use of 1% baby shampoo formulations as a nasal rinse, but there is no literature to date that evaluates its use against HCoV or other viruses. Our study shows that a 1% baby shampoo solution was effective at inactivating HCoV in a time‐dependent manner. The dilute rinse was able to reduce the amount of infectious virus by close to 99% after a contact time of 1 min and greater than 99.9% after a contact time of 2 min. With a contact time of 30 s 1% baby shampoo showed variable results ranging from less than 90% reduction in infectious virus to up toward a 99.9% reduction. Overall the results show a clear time‐dependent decrease of infectious virus. In contrast, a commonly used saline rinse formulation (Neti‐Pot) had no effect on infectious viral count in our study. Most of the common over‐the‐counter mouth washes/gargles tested demonstrated at least a 90% reduction in infectious virus at 1 min of contract time with the majority of products showing increasing virucidal activity with longer contact times. The products had varying active ingredients and formulations. Interestingly, three of the products tested (Peroxide Sore Mouth, Orajel Antiseptic Rinse, and 1.5% H₂O₂) all contained 1.5% H₂O₂ as their active ingredient. With these three products there were variable results with a reduction of infectious virus ranged from below 90% to 99%. The similar results obtained from all three products suggest that the inactive ingredients that are in the Peroxide Sore Mouth and Orajel Antiseptic Rinse provide no noteworthy additional effect toward inactivating the infectious virus. These results agree with a recently published study showing that both 1.5% and 3% H₂O₂ showed between a 90% and a 99% decrease in infectious HCoV…”
• See also The New York Times – No, Mouthwash Will Not Save You From the Coronavirus – Even if people coated the inside of their mouths with a coronavirus-killing chemical, a substantial amount of the virus would still remain in the body.
• See also Washington Post – What those studies on mouthwash and coronaviruses actually mean