Antiseptic mouthwashes insufficient against COVID-19

Despite encouraging in vivo evidence, antiseptic mouthwashes do not substantially reduce the coronavirus disease 2019 (COVID-19) viral load in saliva, a recent study has found.

Researchers conducted a multicentre, blinded, parallel-group, placebo controlled randomized trial of 84 patients who had had COVID-19. The trial had five study groups, including one each for four different mouthwashes (cetylpyridinium chloride, chlorhexidine, povidone-iodine, and hydrogen peroxide) and one control arm that rinsed their mouths with distilled water. Quantitative PCR was used to measure salivary viral load at baseline and 30, 60, and 120 minutes after the mouth rinse.

At baseline, salivary viral loads ranged from 10²–10⁶ copies/mL, with a detected maximum of 10¹⁰ copies/mL. Though individual responses were highly variable, none of the tested mouthwashes led to significant overall declines in salivary viral loads.

Of note, participants who rinsed with povidone-iodine and cetylpyridinium chloride led to mean viral reductions of around 30 percent 2 hours after treatment. Moreover, 59 percent to 65 percent of participants who received either mouthwash saw a 50-percent decrease in viral load.

“The potent virucidal effects against different coronavirus detected in vitro resulted in oral mouthwashes being recommended during the pandemic and [being] routinely used around the world in different clinical situations,” the researchers said.

“However, if the action of oral antiseptics in vivo is limited, their use could provide a false sense of security. Thus, we recommend that strict preventive measures should stand in place in clinical settings until viral infectivity studies in cell lines with post-mouthwash saliva are performed,” they added. “These viral culture studies with oral samples after the use of oral mouthwashes are warranted.”