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Mouthwash Wipes Out COVID Germs — But Don’t Drown Yourself in Listerine

A new study found that mouthwash can kill off virus germs in the mouth. Will it actually protect you?

Rather than halting the impact of the pandemic via actual governmental action, we’ve all been forced to basically take a DIY-approach to public health. That same ethos behind everyone trying to fashion medical face masks out of old T-shirts continues still: Even scientists seem to be scrambling, trying anything they can to figure out something that makes a difference. Case in point, researchers from Penn State’s College of Medicine studied the COVID-inactivating effects of various household products, like baby shampoo, neti pots and mouthwash. As it turns out, their efforts weren’t entirely in vain: Certain mouthwashes can indeed inactivate COVID-19 germs. 

Unfortunately, that really doesn’t mean much. 

Specifically, in a study published this month in the Journal of Medical Virology, researchers found that mouthwashes and oral rinses containing alcohol or peroxide killed off at least 90 percent of COVID-19 virus germs within the mouth when swished for at least 30 seconds. Crest Pro-Health, containing 0.07 percent cetylpyridinium chloride as its active ingredient, killed off 99.9 percent of germs. Antiseptic, alcohol-based rinses were similarly effective, with Listerine Antiseptic killing 99.99 percent of germs within 30 seconds. 

So, yes, when used properly, mouthwash can indeed kill off the virus within the mouth. The problem, though, is that the virus doesn’t exclusively live in the mouth, and the effects are only temporary. 

“If an uninfected person gargles with mouthwash in the morning, one could expect that the mouth may be free of specific coronaviruses for a period of time, but that’s likely about 10 minutes,” Carlos Malvestutto, infectious diseases expert at The Ohio State University Wexner Medical Center, told Prevention. “Any protective effect would be gone as soon as the hydrogen peroxide or ethanol in the mouth evaporates. It’s hard to see what sort of practical use this may have.”

Okay, so it’s not nothing. If regularly using mouthwash prevents people from spreading COVID or from becoming infected even for just a few minutes, that’s still an improvement. But in order for it to really make a difference, everyone would need to be rinsing with mouthwash multiple times an hour while still keeping their nose covered. 

In no way is mouthwash any sort of “cure,” “treatment” or even really a solid preventative measure. Maybe you can add gargling some Listerine to your list of practices like washing your hands upon returning home from the grocery store, but it’s mostly wishful thinking that it could help in a practical way. Who knows, though — it’s possible this news could lead to further advancements that actually make a difference. We can hope, right?