By Saabira Chaudhuri 

Wash your hands, wear a mask and don't forget to gargle with mouthwash.

That's the message Unilever PLC and Colgate-Palmolive Co. are carefully starting to push after research they commissioned showed that certain types of mouthwash and toothpaste could potentially help deactivate the virus that causes Covid-19.

Now, Unilever is launching mouthwash brands in new markets, while Colgate has shared the results of its study with dentists.

Reducing virus particles in the mouth could help fight against the pandemic, the companies said, because Covid-19 can be spread through droplets generated when an infected person coughs, sneezes or speaks. Both companies said the mouthwashes dissolve the outer protective layer of virus particles, preventing them from attaching to cells and infecting them.

But based on tests so far they can't definitively say how long the benefit would last or what impact coughing would have. That makes it hard to judge how useful oral-hygiene products could be in curbing transmission.

Unilever said an October lab-based study it commissioned found mouthwash containing cetylpyridinium chloride, or CPC -- an ingredient used by dentists for its antibacterial properties -- reduced SARS-CoV-2 particles by 99.9% after 30 seconds of rinsing.

"While we are clear that this is not a cure or proven way to prevent the transmission of coronavirus, the results are very promising," said Glyn Roberts, Unilever's head of research and development for oral care.

Early in the pandemic, scientists from Cardiff University in Wales and other institutions called for more research into the potential role of mouthwash in fighting Covid-19. Previous studies, they said, had shown that ingredients commonly found in mouthwashes could deactivate other viruses. Mouthwash makers say sales have risen this year amid broader demand for hygiene products.

Angela Rasmussen, an associate research scientist at Columbia University's Center of Infection and Immunity who reviewed the results of the study commissioned by Unilever, said that the findings were promising but results from human trials are needed.

"What happens in a culture dish is not indicative of what would happen in a patient's actual mouth and throat," said Ms. Rasmussen. "While it's great for a short period of time to reduce virus secreted by those cells, what really is going to be important is how long that effect will last."

Unilever said it plans to follow its study -- in which scientists from Microbac Laboratories used a culture dish to simulate the viral load in the mouth -- with a trial in at least 50 people early next year. It will also look into how mouthwashes could impact other viruses.

In the meantime, Unilever is launching mouthwash with CPC in a string of new markets, from Italy and France to India and Indonesia, under brands including Pepsodent, Mentadent, Signal and Close-Up. The company doesn't plan to launch these in the U.S., where its oral-care business is smaller and the regional rights to some of the brands are held by other companies.

Unilever isn't making any new claims on product packaging, but has been promoting its findings through social media and its website.

Colgate, the world's largest toothpaste maker, said its lab tests, conducted by Rutgers New Jersey Medical School, also showed some kinds of toothpaste, mouthwash and mouth spray can virtually eliminate the virus that causes Covid-19. The toothpastes contain zinc or stannous, a mineral that can help fight gum disease, while the mouthwashes contain CPC.

Colgate said it is sharing its findings with dentists and notes many are now asking patients to rinse before procedures to reduce the possible presence of the virus.

The company said a separate clinical trial testing mouthwash on 50 hospitalized people suggested the benefit could last between 30 and 60 minutes after rinsing. Full results haven't yet been shared.

The company is also funding additional clinical studies in the U.S. and Brazil in which 260 people with Covid-19 are participating.

"We think oral care has a role to play in fighting the global pandemic, alongside other preventive measures," said Colgate's Chief Clinical Officer Maria Ryan.

Some companies say it is too early to make any virus-related claims about mouthwash or toothpaste.

Johnson & Johnson, owner of Listerine, said lab-based findings about oral-care products and the virus, while high quality, aren't sufficient to advocate the use of mouthwash as a prevention measure.

"Listerine Antiseptic is not intended to prevent or treat Covid-19 and should be used only as directed on the product label," a spokeswoman said, adding that J&J intends to actively participate in the scientific exchange on this topic.

In October, J&J said its third-quarter oral-care sales grew 10.8%, partly attributing the rise to "increased demand globally related to the Covid-19."

Procter & Gamble Co. isn't commissioning its own studies and said it is too early to tell how mouthwashes impact the virus. It said its Crest mouthwashes, many of which contain CPC, are being tested by third parties.

Write to Saabira Chaudhuri at saabira.chaudhuri@wsj.com

 

(END) Dow Jones Newswires

December 12, 2020 05:44 ET (10:44 GMT)

Copyright (c) 2020 Dow Jones & Company, Inc.