The idea came from a new study that found that a coronavirus that causes common colds — not the one that causes Covid-19 — could be killed in a laboratory by dousing virus-infected cells with mouthwash. The study’s authors concluded that the products they tested “may provide an additional level of protection against” the new coronavirus.
But outside experts warned against overinterpreting the study’s results, which might not have practical relevance to the new coronavirus, which has killed more than 220,000 Americans. Not only did the study not investigate this deadly new virus, but it also did not test whether mouthwash affects how viruses spread from person to person.
“I don’t have a problem with using Listerine,” said Angela Rasmussen, a virologist at Columbia University. “But it’s not an antiviral.”
The study, which was published last month in the Journal of Medical Virology, looked only at a coronavirus called 229E, which causes common colds — not the new coronavirus.
The researchers flooded 229E coronaviruses grown in human liver cells in the lab with several types of mouthwash and nasal rinses for 30 seconds, one minute or two minutes — longer than the typical swig or spritz into a nose or mouth. Around 90 to 99 percent of the viruses could no longer infect cells after this exposure, the study found.
But because the study didn’t recruit any human volunteers to gargle the products in question, the findings have limited value for the real world, other experts said. The human mouth, full of nooks and crannies and a slurry of chemicals secreted by a diverse cadre of cells, is far more complicated than the inside of a laboratory dish.
Researchers warn people not to misuse mouthwash or nasal rinses or ingest large quantities of the liquids, because they can be dangerous.