More than a third of us use mouthwash, whether just for an extra burst of minty freshness after brushing our teeth or to tackle bleeding gums. However, instead of improving the performance of your toothbrush, this habit can endanger your health.
For more than a decade, studies have suggested that mouthwash may increase the risk of certain cancers. Now new research has reiterated this warning for users of one of the country’s favorite options. But you may not need to completely clean out your bathroom cabinets just yet.
Dangers of mouthwash?
In the latest study from researchers in Belgium, which originally examined the impact of daily mouthwash on STD risk among 59 men, volunteers used Listerine Cool Mint daily for three months, followed by three months with a placebo mouthwash, or vice versa.
Interestingly, the results also showed that the mouthwash containing Listerine, which rids the mouth of certain germs behind bad breath and plaque, increased the levels of two bacteria in the mouth (fusobacterium nucleatum And Streptococcus anginosus) at. Separate research has linked these types to esophageal and colorectal cancer.
The theory is that the alcohol, antiseptics or flavorings found in mouthwash alter the microbiome and cause changes in the growth pattern of the cells, which could influence the chance of developing cancer, explains Prof. Karol Sikora, a renowned oncologist and honorary professor of professional practice. at the University of Buckingham.
In addition, a chemical called acetaldehyde is produced in the mouth after using an alcohol-containing mouthwash, notes Dr. Zoe Brookes, associate professor of dental education and research at the University of Plymouth. It is this chemical that is thought to be a possible carcinogen, she adds.
In response to their findings, the study authors urged people not to use mouthwash.
This is not the first time this worrying link has been reported. A 2009 article by the then president of the Australian Dental Association warned that mouthwashes containing alcohol increase the risk of oral cancer. It referred to a 2007 study that found the fluorescent liquid was linked to a threefold higher risk of developing head and neck cancer.
However, none of these studies prove that mouthwash causes cancer. And a 2023 review warned that the evidence linking mouthwash and cancer is “limited and conflicting,” as other studies have found no link between mouthwash use and cancer.
Other studies have identified a cancer problem only if that bacteria is found in the intestines, she notes. “But the fact that fusobacterium can cause colon cancer in the intestines does not mean that bacteria in the mouth will also cause oral cancer; that is too big a step,” she says.
However, there are other risks. In addition to cancer concerns, some studies have linked frequent mouthwash use to diabetes and high blood pressure, says Dr Mia Burleigh, a senior lecturer at the University of the West of Scotland, who researches the microbiome and oral health.
This is thought to be caused by mouthwash decreasing the rate at which the mouth converts a compound found in food called nitrate into nitric oxide as it rids the mouth of certain bacteria.
“Healthy sources of nitrate include vegetables and roots, such as dark leafy greens and beetroot,” she explains. “Without key bacteria in our oral microbiome, nitric oxide production is reduced, affecting glucose metabolism, insulin sensitivity and cardiovascular control through the regulation of blood vessel dilation.”
What is in mouthwash?
Although ingredient lists vary dramatically between mouthwashes, five key components can be found in most options on pharmacy and supermarket shelves, says Dr. Tom Crawford-Clarke, dentist and founder of Luceo Dental in London.
Fluoride is one of the most common. It protects the teeth from acids produced by plaque, preventing tooth decay.
Antibacterial agents are also used to reduce the number of microorganisms in our mouths and balance the pH levels, which helps prevent tooth decay and tackles bad breath, he explains.
Examples include cetylpyridinium chloride, which prevents bad breath and plaque from maturing, and chlorhexidine digluconate, found in Corsodyl, which reduces bacterial counts and helps control the early signs of gum disease.
Essential oils are also added to freshen breath, provide a “minty feeling” and reduce plaque buildup, while sweeteners are mixed in for flavor, notes Dr. Crawford-Clarke.
Alcohol is the ingredient that gives mouthwash the ‘singing’ effect that stings slightly, helps dissolve oils in the liquid and kills bacteria. It is often found in concentrations of more than 20 percent, which is about double what is found in wine and four times more than in beer. This is one of the reasons why you should never drink it.
The exact mix of ingredients you get will depend on the mouthwash you purchase.
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“If you’re concerned about the research, just buy an alcohol-free mouthwash,” says Prof Brookes. “Then you can avoid what some researchers claim – that alcohol content increases the risk of cancer.”
Dr. Burleigh recommends not using mouthwash unless you have a specific problem that needs to be treated. “There is increasing evidence that mouthwash is harmful to other areas of health, so it is best avoided unless it is prescribed to treat a specific oral health problem,” she says.
“Mouthwashes are not the answer to problems – contrary to what the advertisements would have you believe – and are not a substitute for correct oral hygiene habits such as brushing your teeth and interdental cleaning,” says Dr Crawford-Clarke.
If you do use mouthwash, don’t do it right after brushing because that will wash away the toothpaste, which is better for your teeth, he says.
“It’s much better to use it after meals or at another brushing time if you want to add it to your oral hygiene routine,” says Dr. Crawford-Clarke. “If you’re concerned about the alcohol content, I would look for one that is alcohol-free.”
Alternatives include sugarless gum or mints or using a tongue scraper, he adds.
A spokesperson for Listerine said: “Studies on Listerine’s impact on oral health have been published in hundreds of peer-reviewed publications for over a century, making it one of the most extensively tested brands of mouthwash in the world. We are constantly evaluating the latest science. There is no evidence that Listerine causes cancer.”
The fastest ways to freshen your breath
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Chew sugar-free gum: stimulates saliva production, which protects the teeth
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Drinking water: Keeps the mouth hydrated and helps rinse away dirt after meals
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Eat beetroot and spinach: vegetables high in nitrate (a prebiotic) help balance the ‘good’ and ‘bad’ bacteria in the mouth and reduce acidity
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Regular brushing and flossing: Removes plaque and food particles that cause bad breath