Is Mouthwash Really Effective Against COVID-19?

by | May 27, 2020 | General Health & Wellness, Oral Hygiene

Depending on how much online surfing you allow yourself during the pandemic, you may have seen a bit of mouthwash click-bait recently. Here are just a few of the headlines we’ve seen:

headline reading: mouthwash could be a promising weapon in the fight against coronavirus transmission

headline reading: coronavirus myth busted: using a mouthwash won't kill the virus or prevent COVID-19

headline reading: COVID-19 update: coronavirus infection can be prevented by mouthwash potentially destroying outer layer of COVID-19

headline reading: Coronavirus myth: mouthwash can reduce the spread

So which is it? Does it help or not?

Inspiring those headlines was a new paper published in the journal Function, reviewing earlier studies on the effectiveness of dental rinses on coronaviruses in general in light of the current pandemic. Its authors included medical experts, virologists, and lipid specialists from Cardiff University in Wales, along with researchers from several other universities.

Their motivation was clear.

Dental practitioners are at elevated risk of exposure to SARS-CoV-2, and there are guidelines that advocate use of mouthwash clinically. Previously published CDC guidelines for infection control in the dental setting have cited the potential usefulness of pre-procedural mouthwashes in reducing the spread of airborne pathogens of all types.

Other research has similarly pointed to saliva, salivary glands, and tongue as hosts of COVID-19. Thus, if an infected person coughs, sneezes, or talks, droplets containing the virus may enter the air. Should another person inhale those droplets, they may become infected, too.

But here’s the thing: Coronaviruses, like COVID-19, are surrounded by an outer lipid (fat) membrane. Inside that “envelope” are the glycoproteins that are key for infection. This, according to the new Function study is also what makes coronaviruses vulnerable.

It is widely known that interfering with the lipid envelope represents a virucidal strategy to target many coronaviruses, with a large body of work evidencing the impact of many agents.

mouthwash and toothbrushDespite this, there’s been little discussion about or studies proposed to investigate the potential role of mouthwashes that contain ingredients that could break through the lipid envelopes and possibly keep the virus from being transmitted. So the authors set out to remedy this.

Together, they reviewed multiple studies on the effects of different mouthwash components on “other enveloped viruses.” These include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide, and povidone-iodine. And, all in all, they found that the research

directly support[s] the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2. Research to test this could include evaluating existing or specifically-tailored new formulations in well-designed viral inactivation assays, then in clinical trials. Population-based interventions could be undertaken with available mouthwashes, with active monitoring of outcome to determine efficacy. This is an under-researched area of major clinical need.

In other words, much more work remains to be done, including testing such rinses against COVID-19 specifically. But this seems a promising line of research, to say the least.

Another promising bit of news? Because the lipid envelope doesn’t change when viruses mutate, if a rinse proves effective, it should still work against future coronavirus strains.

Scientists at Aga Khan University and the University of Karachi in Pakistan have already begun a clinical study on antiviral gargles and their effect on COVID-19, and more are sure to follow.

But for now this report shows the potential for oral mouthwashing to reduce infection risk – in the dentist’s office and elsewhere. And while for everyday rinsing, alcohol-free, non-chlorhexidine mouthwashes are preferred, there are times when stricter protocols do call for these types of products.

With risks elevated due to COVID-19, now is one of those times.

Mouthwash image by Marco Verch

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