Health and Wellness

Common mouthwashes may have the potential to reduce Covid-19 viral load in the mouth

Mouthwash. (Photo By BSIP/UIG Via Getty Images)
BSIP | Universal Images Group | Getty Images

Some common drugstore items may have the potential to reduce the oral "viral load" of SARS-CoV-2, the coronavirus that causes Covid-19, among those suffering from the illness, according to researchers.

In a recent study published in the Journal of Medical Virology, researchers at Penn State College of Medicine said certain oral antiseptics, mouthwashes and a baby shampoo "may have the ability to inactive human coronaviruses" when talking, sneezing or coughing, though further testing is needed.

However other experts are skeptical about the usefulness or relevance of these findings, as the study did not specifically test the SARS-CoV-2 strain of coronavirus, and it did not test the usefulness of the products in people.

Still, Penn State researchers call the findings "promising" and lead them to believe that certain oral rinses and other products tested could potentially help reduce the spread of SARS-CoV-2 as well, the report said.

"The researchers found that several of the nasal and oral rinses had a strong ability to neutralize human coronavirus, which suggests that these products may have the potential to reduce the amount of virus spread by people who are COVID-19-positive," Penn State said in a release.

Craig Meyers, a professor of microbiology and immunology and obstetrics and gynecology, who led the study, along with his team of researchers, have been studying different ways to lower the transmission and spread of human coronaviruses through aerosolized respiratory droplets, which is a method of transmission of SARS-CoV-2.

According to Meyers, "I was in the drugstore and I just saw the bottle of Listerine, and it said 'kill germs that cause bad breath.' And I thought, 'What the heck?' I bought it and we threw it into the studies and we were a little surprised on how well it worked" at inactivating human coronaviruses, Meyers tells CNBC Make It.

Another study published in July by the Journal of Infectious Diseases did link certain oral rinses to inactivating SARS-CoV-2. Researchers in Germany tested eight commercial mouthwashes in a cell culture test and found Sars-CoV-2 viral load was reduced dramatically after 30 seconds. However, the authors concluded that further studies are still needed and that mouthwashes are not suitable for treating Covid-19.

Meyers also says that more clinical trials are still needed to determine if the products they tested (J&J Baby Shampoo, Orajel Antiseptic Rinse, Listerine Antiseptic and Peroxide Sore Mouth, to name a few) can reduce the amount of the virus in Covid-19 positive patients' oral cavity and what specific ingredients in the solutions tested inactivated the virus.

To conduct the study, Meyers and his team of scientists, used a strain of human coronavirus called 229e, which he says is structurally similar to SARS-CoV-2. (Meyers says special facilities are needed to use SARS-CoV-2 and most of them have been booked up during the pandemic. Plus, viruses like 229e "have a strong foundation for being an accurate surrogate" to SARS-CoV-2, he says. However other experts say the two viruses are not interchangeable.)

Researchers put the virus in a solution with each of the products for 30 seconds, then one minute and finally for two minutes. (Critics point out the timing is likely longer than the average person would keep mouthwash in their mouth.) To detect how much of the virus was inactivated, researchers diluted the solutions and put them in contact with human cells.

After a few days, they counted how many human cells remained alive after exposure to the products. Among the findings, the 1% baby shampoo solution inactivated the virus by 99.9% after two minutes, while several mouthwashes were able to inactivate the virus by 99.9% after only 30 seconds of contact time.

"Even if the use of these solutions could reduce transmission by 50%, it would have a major impact," Meyers said in a release on Monday. But without more clinical trials, Meyers says its too early to know exactly how these findings would be put into use by people to potentially slow down the spread of Covid-19.

Though Meyers personally uses mouthwash twice a day he cautions people not to use these products in the hopes of fighting Covid-19.

"I would say wear your mask, do your social distancing. Do what you're suppose to be doing but this could just be an extra help," Meyers says.

This story has been updated to include additional criticisms of the Penn State study.

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