Not sure how this would (or does) work IRL, but yet another study has concluded that mouthwashes may have “a strong ability to neutralize human coronavirus”.
The strong disclaimer that must be tacked on to such findings, however, is this: This may very well be true in the lab, but it does not prove that mouthwashes also protect people against COVID-19 infections out in the real world.
As the authors of this study add: “Clinical trials are needed to determine if these products can reduce the amount of virus COVID-positive patients or those with high-risk occupations may spread while talking, coughing or sneezing.”
But they also add, and this is obviously true, “Even if the use of these solutions could reduce transmission by 50%, it would have a major impact .”
So all in all, I imagine that in the short term, at least, namely, the next few months, regular use of mouthwash, especially for people who consider themselves at high risk of infection, would be very unlikely to lead to much harm.
Longer use, though, as well as use of large doses of mouthwash might be linked to adverse effects so as always, do your due diligence before starting to use this tactic.