Mouthwashes may help lower the transmission and spread of the coronavirus, according to a new study.
In the study, published in the Journal of Medical Virology, researchers investigated over-the-counter mouthwashes and nasal rinses commonly found in drug stores and supermarkets, since both types of products "directly impact the major sites of reception and transmission of human coronaviruses (HCoV)" — namely, the mouth and nose — and "may provide an additional level of protection against the virus."
To find out whether mouthwashes and nasal rinses would be effective against the coronavirus, the researchers tested a common human coronavirus known as 229e — one of several strains that typically only cause mild infections like the common cold, according to the Centers for Disease Control and Prevention — not SARS‐CoV‐2, which is the virus associated with Covid‐19.
But, as the lead author of the study, Craig Meyers, tells Yahoo Life, all coronaviruses have something in common: "They have a membrane," says Meyers, a distinguished professor of microbiology and immunology at Penn State.
"With membrane viruses, all you have to do is break that membrane and they're inactivated," Meyers explains. "It's very difficult to work with the actual Covid-19 virus. But the membranes [in coronaviruses in general] are pretty much the same."
The researchers tested whether certain nasal rinses, such as Neti Pot with a salt/baking soda solution and a diluted 1 percent Johnson's Baby Shampoo solution and mouthwashes, including Listerine Antiseptic, Listerine Ultra, Orajel Antiseptic Rinse, and Crest Pro‐Health, could inactivate high concentrations of human coronaviruses after using the products for 30 seconds, one minute, and two minutes.
The results: The Listerine mouthwashes, as well as Crest Pro-Health, Equate Antiseptic mouthwash, and CVS Antiseptic mouthwash, were "highly effective at inactivating infectious virus with greater than 99.9 percent," according to the researchers in the study — even after only swishing around the mouthwash for 30 seconds.
The researchers also found that the mouthwash products with hydrogen peroxide (H2O2) as their active ingredient — such as CVS' Peroxide Sore Mouth and Orajel Antiseptic Rinse — "all demonstrated similar abilities to inactivate" the human coronavirus 229e by 90 to 99 percent.
With nasal rinses, the researchers found that using a 1 percent baby shampoo solution for either one to two minutes inactivated more than 99 percent of the virus in both cases. But the over‐the‐counter saline nasal rinse, Neti Pot, had "no effect on the infectivity of the virus at any incubation time tested."
The researchers concluded that these commonly-available healthcare products have "significant virucidal properties with respect to" human coronaviruses.
Pictures of the week: November 1 - 7
Pictures of the week: November 1 - 7
LONDON, ENGLAND - NOVEMBER 05: A plane prepares to land at Heathrow Airport with the moon behind it on November 05, 2020 in London, England. (Photo by Chris Jackson/Getty Images)
A cyclist wearing a face mask passes traditional red phone boxes, on the first day of Britain's second lockdown designed to save its health care system from being overwhelmed by people with coronavirus, in London, Thursday, Nov. 5, 2020. Britain joined large swathes of Europe in a coronavirus lockdown designed to save its health care system from being overwhelmed. Pubs, along with restaurants, hairdressers and shops selling non-essential items closed on Thursday until at least Dec. 2. (AP Photo/Matt Dunham)
A woman is detained by police from 'The Million Mask March', an annual event described as a march "against austerity, the infringement of rights, war crimes, corrupt politicians and to reinstate liberty", gather in Trafalgar Square in central London, Thursday, Nov. 5, 2020. The march was taking place on the same day national lockdown rules come into force as Britain joined large swathes of Europe in a coronavirus lockdown designed to save its health care system from being overwhelmed. Pubs, along with restaurants, hairdressers and shops selling non-essential items closed on Thursday until at least Dec. 2. (AP Photo/Alberto Pezzali)
A participant in 'The Million Mask March', an annual event described as a march "against austerity, the infringement of rights, war crimes, corrupt politicians and to reinstate liberty", gathers in central London, Thursday, Nov. 5, 2020. The march was taking place on the same day national lockdown rules come into force as Britain joined large swathes of Europe in a coronavirus lockdown designed to save its health care system from being overwhelmed. Pubs, along with restaurants, hairdressers and shops selling non-essential items closed on Thursday until at least Dec. 2. (AP Photo/Frank Augstein)
A man with a religious sandwich board waits to cross a junction on Oxford Street on the first day of Britain's second lockdown, designed to save its health care system from being overwhelmed by people with coronavirus, in London, Thursday, Nov. 5, 2020. Britain joined large swathes of Europe in a coronavirus lockdown designed to save its health care system from being overwhelmed. Pubs, along with restaurants, hairdressers and shops selling non-essential items closed on Thursday until at least Dec. 2. (AP Photo/Matt Dunham)
Police patrol in Trafalgar Square ahead of a possible anti-lockdown protest in central London, Thursday, Nov. 5, 2020. Britain joined large swathes of Europe in a coronavirus lockdown designed to save its health care system from being overwhelmed. Pubs, along with restaurants, hairdressers and shops selling non-essential items closed on Thursday until at least Dec. 2. (AP Photo/Frank Augstein)
EDINBURGH, SCOTLAND - NOVEMBER 04: Members of the public view a 45ft tall giant golden monkey on the side of Inverleith house on November 04, 2020 in Edinburgh, Scotland. The inflatable Golden Monkey installation, by Australian ecological artist Lisa Roet, has previously adorned scaled skyscrapers in Beijing and Hong Kong. (Photo by Jeff J Mitchell/Getty Images)
Blackpool's annual Illuminations are seen before being switched off at midnight on Wednesday because of the four-week lockdown, Blackpool, England, Wednesday Nov. 4, 2020. The illuminations were due to remain lit for an extra two months this season, until Jan. 3, to aid the town's tourism trade hit by COVID-19 restrictions. (AP Photo/Jon Super)
The sun rises over Houghton on the Hill in Leicestershire on the first day of a second national lockdown for England. (Photo by Joe Giddens/PA Images via Getty Images)
LONDON, UNITED KINGDOM - NOVEMBER 04: Police officers warn people who continue to spend their times at a street as the 2nd national lockdown, which was announced to imposed to stem the spread of the novel coronavirus (COVID-19) pandemic, begins in central London, United Kingdom on November 04, 2020. One person was detained during the police officers interventions. (Photo by Hasan Esen/Anadolu Agency via Getty Images)
People sitting outside the Cock and Lion pub in Marylebone on the eve of the 2nd Lockdown in London.
Pubs and restaurants to close as England forced into new national coronavirus lockdown. (Photo by Dave Rushen / SOPA Images/Sipa USA)
Commuters on a Jubilee Line Underground train at Canning Town station, London, at 0720 in the morning rush hour at the start of a four week national lockdown for England. (Photo by Victoria Jones/PA Images via Getty Images)
A rainbow appears over an oast house, near Hawkhurst in Kent, England, Tuesday, Nov. 3, 2020. Oast houses are a distinctive feature of the Kent and Sussex landscape and were constructed originally to dry the harvested mature hops used as an ingredient in brewing beer. (Gareth Fuller/PA via AP)
Graffiti of a woman with an axe part of the Halloween Paint Jam seen at the famous Leake Street Tunnel under Waterloo station (Photo by Dave Rushen / SOPA Images/Sipa USA)
A view of the RRS Sir David Attenborough, the UK's most advanced polar research ship, as it travels down the River Mersey leaving Liverpool ahead of two weeks of technical trials off the coast of north Wales, with one of Anthony Gormley "Another Place" sculptures in the foreground, in Liverpool, England, Tuesday, Nov. 3, 2020. (Peter Byrne/PA via AP)
Britain's Prime Minister Boris Johnson walks back towards10 Downing Street following a cabinet meeting in London, Tuesday, Nov. 3, 2020. The Cabinet meeting is held in the Foreign Office to allow for social distancing due to the ongoing Coronavirus pandemic, rather than the normal 10 Downing Street. (AP Photo/Frank Augstein)
Members of staff poses with a grey limestone Buddha head from the 7th century Tang Dynasty (estimated GBP80,000-120,000) in the fine Chinese art section of the Asian Art Week collection at Bonhams auction house on New Bond Street in London, England, on November 2, 2020. The sale takes place on November 5. (Photo by David Cliff/NurPhoto via Getty Images)
EDITORIAL USE ONLY The Carnaby Christmas installation this year is titled Choose Love In Carnaby and is in collaboration with charity Choose Love. A series of pink neon light boxes are suspended the length of Carnaby Street that beam poignant words of hope. The words pay tribute to the strength and courage of Londoners and the whole of the UK. Other words of empowerment include believe, heal, brave, dream, faith, together and family.
As the UK reacts to Prime Minister Boris Johnson's announcement of Lockdown 2 during the second wave of the Coronavirus pandemic, face shields and masks are on sale in a window of a retailer on Oxford Street, on 2nd November 2020, in London, England. From midnight on Thursday, all non-essential shops, bars, restaurants and other small businesses will have to closed, according to government Covid restrictions - and for a minimum of 4 weeks in the run-up to Christmas. (Photo by Richard Baker / In Pictures via Getty Images)
Johnny Depp fan, Matty, dressed as Gellert Grindelwald, the character Depp plays in the third Fantastic Beasts movie which is currently being filmed, reacts as he hears Depp had lost his libel case, outside the High Court in London, Monday, Nov. 2, 2020. Britain's High Court has ruled against Johnny Depp in his libel action against the owner of the Sun tabloid over allegations that he was a "wife beater." (AP Photo/Matt Dunham)
LEEDS, ENGLAND - NOVEMBER 02: Jamie Vardy of Leicester City shakes hands with Brendan Rodgers, Manager of Leicester City after being substituted during the Premier League match between Leeds United and Leicester City at Elland Road on November 02, 2020 in Leeds, England. Sporting stadiums around the UK remain under strict restrictions due to the Coronavirus Pandemic as Government social distancing laws prohibit fans inside venues resulting in games being played behind closed doors. (Photo by Jon Super - Pool/Getty Images)
British Prime Minister Boris Johnson waves at the media as he leaves 10 Downing Street in London, to go to the Houses of Parliament to deliver a statement on England's upcoming coronavirus lockdown, Monday, Nov. 2, 2020. Johnson on Saturday announced a new month-long lockdown for England that will start on Thursday, after being warned that without tough action a resurgent coronavirus outbreak will overwhelm hospitals in weeks. (AP Photo/Matt Dunham)
The London Eye is seen lit up Red, White and Blue to celebrate The Pride of Britain Awards 2020. (Photo by Brett Cove / SOPA Images/Sipa USA)
Shoppers queue outside the IKEA store in Greenwich, London before the 2nd Lockdown in England starts on the 5th of November meaning all non essential shops will have to shut for up to a month. (Photo by Dave Rushen / SOPA Images/Sipa USA)
Several hundreds of demonstrators protest in Piccadilly Circus against Poland's top court ruling that abortion of fetuses with congenital defects is unconstitutional, on 01 November, 2020 in London, England. Poland's abortion laws are already among the strictest in Europe and the recent decision by the Constitutional Court further limits access to abortions, which will only be legal in cases of rape or incest, or to protect the mother's life. (Photo by WIktor Szymanowicz/NurPhoto via Getty Images)
A newborn grey seal pup on the beach at Horsey in Norfolk, as the pupping season begins at one the UK's most important sites for the mammals.
Tottenham's Gareth Bale, centre, heads the ball to score his team's second goal during the English Premier League soccer match between Tottenham Hotspur and Brighton & Hove Albion at Tottenham Hotspur Stadium, London, Sunday, Nov. 1, 2020. (Julian Finney/Pool via AP)
LONDON, ENGLAND - NOVEMBER 01: Stormzy performs on stage during McDonald's I'm Lovin' It Live at The Printworks on November 01, 2020 in London, England. (Photo by Samir Hussein/WireImage)
Referee Graham Scott consults with VAR before awarding a goal to Brighton's Tariq Lamptey during the English Premier League soccer match between Tottenham Hotspur and Brighton & Hove Albion at Tottenham Hotspur Stadium, London, Sunday, Nov. 1, 2020. (Mike Hewitt/Pool via AP)
Manchester City's Lucy Bronze, left, and Keira Walsh, right, celebrate with Manchester City's manager Gareth Taylor, center, after winning the Women's FA Cup final soccer match between Everton and Manchester City at Wembley stadium in London, Sunday, Nov. 1, 2020. (Facundo Arrizabalaga/Pool via AP)
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However, more research is needed — namely, clinical trials to pinpoint which ingredient or combination of ingredients is breaking the virus' membrane. Meyers tells Yahoo Life that he hopes to get funding to test which ingredients are the most effective.
This isn't the first study to look at mouthwash products as a way to reduce viral load. In a July 2020 study published in the Journal of Infectious Diseases, researchers tested eight different mouthwashes from pharmacies and drugstores in Germany and found that they all reduced the viral load — in fact, three mouthwashes "reduced it to such an extent that no virus could be detected after an exposure time of 30 seconds," according to ScienceDaily.
But the German study's authors emphasize that this doesn't mean mouthwashes alone can treat Covid-19. "Gargling with a mouthwash cannot inhibit the production of viruses in the cells," lead author of the study Toni Meister of Ruhr University Bochum in Germany, told ScienceDaily, "but could reduce the viral load in the short term where the greatest potential for infection comes from, namely in the oral cavity and throat — and this could be useful in certain situations, such as at the dentist or during the medical care of Covid-19 patients."
Meyers agrees, saying: "You've got to be wearing your mask and social distancing. To me, [mouthwash] is an extra help."
Nicholas Rowan, MD, an assistant professor of otolaryngology at Johns Hopkins Medicine, tells Yahoo Life that the use of mouthwashes and nasal rinses are a "really promising area" and are "very exciting therapies, logical, and likely very low risk."
And, like Meyers, Rowan says that more research is needed. "There is a lot of credence to these claims," he tells Yahoo Life. "However, the most significant barrier of these medications is lack of proven efficacy, and navigating the appropriate clinical trials before providing these types of medications to patients."
Rowan adds: "It's hard to say that these therapies are really incredibly effective or have a place in the treatment paradigm for Covid-19 just yet. It's likely an option for patients to use, but overall, there is not great evidence that current, available options have a real benefit. Fortunately, these over-the-counter medications are likely low risk."