Alcohol-based mouthwash may disrupt the oral microbiome, causing gum disease and cancer

Using alcohol-based mouthwashes may increase your risk of developing diseases such as gum disease and some types of cancer, including colorectal cancer.

These are the results of a study conducted at the Institute of Tropical Medicine in Antwerp, Belgium, led by graduate student Joleine Lauman from the Department of Clinical Sciences.

The study was published in the Journal of Medical Microbiology.

In the study, researchers found significant changes in the composition and number of bacteria in participants' oral microbiome after using Listerine Cool Mint, an alcohol-based mouthwash.

Two species of bacteria - Fusobacterium nucleatum and Streptococcus anginosus - were found to increase significantly after daily use of the mouthwash. These bacteria are associated with several diseases, including gum disease, esophageal cancer and colorectal cancer.

Scientists also noted a decrease in the number of bacteria of the genus Actinobacteria.

The researchers did not collect information about the participants' eating habits or smoking habits. They also did not recommend that the public stop using alcohol-based mouthwashes entirely.

Participants used a Listerine mouthwash for three months followed by a non-alcoholic mouthwash for three months, or vice versa.

The goal of the study was to find ways to reduce the incidence of gonorrhea, chlamydia and syphilis in men who have sex with men.

Alcohol based mouthwash vs. Non-alcoholic mouthwash

According to Alliance Dental, most mouthwashes sold in pharmacies contain alcohol. These mouthwashes may cause a short-term burning sensation in the mouth, an unpleasant taste, and dry mouth.

Alcohol also destroys almost all bacteria in the mouth - both good and bad.

Alcohol-free mouthwash does not eliminate all bacteria, but it does create a new balance of bacteria in the mouth.

The researchers said that people with dry mouth problems, such as patients undergoing radiation treatment, taking certain medications, or having medical conditions such as diabetes or Sjögren's syndrome, may prefer an alcohol-free mouthwash. People with a history of alcohol addiction and those who have extensive dental restorations may also prefer an alcohol-free mouthwash.

"Alcohol-based mouthwashes are widely available," Lauman said in a press release. "The public can use them daily to combat bad breath or prevent periodontal disease, but should be aware of the possible consequences. Ideally, long-term use should be under the guidance of medical professionals."

Should I use an alcohol-based mouthwash?

Researchers reported that use of the alcohol-based Listerine mouthwash showed an increase in opportunistic bacteria, which may increase the risk of periodontal disease, esophageal and colorectal cancer, and systemic diseases.

"We found that Listerine Cool Mint had a negative effect on some beneficial bacteria," said Chris Kenyon, Ph.D., professor at the Institute of Tropical Medicine and one of the study's authors. "For example, it reduces the number of Actinobacteria bacteria. Various Actinomyces species are part of the oral nitrate-reducing bacteria that convert salivary nitrate into nitrite for further production of the powerful vasodilator nitric oxide, important for maintaining normal blood pressure. The nitrate-nitrite-nitric oxide pathway is an important mechanism linking the oral microbiome to cardiovascular health."

The authors note that regular use of Listerine should be used with caution and careful consideration.

"It [the alcohol-based rinse] may be safe for use for short periods, but based on our findings and other data, I would not recommend long-term use," Kenyon told Medical News Today.

However, at least one expert says it's important to remember that using mouthwash does not directly lead to cancer.

"Alcohol mouthwash may be a contributing factor if the person also smokes, drinks alcohol or has an unhealthy diet, but research does not suggest it is the only cause of cancer. Long-term use is also required," said Dr Eric Usher, a general practitioner at the hospital Northwell Lenox Hill in New York.

"The type of rinse that should be used is determined by your specific dental needs, which can be discussed at your bi-annual dental exam. This is determined based on the condition of the enamel (the layer that protects the teeth) and the overall health of the teeth," added Usher, who participated in the study.

"The researchers stress that the study's findings do not mean the public should stop using mouthwash entirely," he added.

Limitations of the mouthwash and cancer study

The study had several limitations.

Oral sampling was limited to the palatal arches and the posterior part of the oropharynx. The authors note that the results may not be representative of the entire oral cavity. Compliance with the use of rinse aid was not monitored. The changes were not confirmed by the second method. The study included only men who have sex with men. Therefore, the results may not be generalizable to the entire population.