Is your mouthwash safe? What the latest research really says
Recent headlines have raised concerns about mouthwash and cancer risk—but how worried should you be? Experts separate fact from myth.
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Recent headlines have raised concerns about mouthwash and cancer risk—but how worried should you be? Experts separate fact from myth.
More than a third of us finish our daily dental routines with a mouthwash rinse, according to a government survey.
But with some studies suggesting an increased cancer risk and stark warnings in the tabloid press, is it actually safe to use mouthwash every day?
Absolutely, says Oral Health Foundation educator Karen Coates: “Our position is that these fears should be interpreted cautiously and in the context of the overall evidence.
“In the Foundation’s published guidance, mouthwash is a useful adjunct to brushing and interdental cleaning, particularly antimicrobial mouthwashes for the treatment of gum disease.”
In other words, the risks are not as clear-cut—or as alarming—as some headlines suggest.
In fact we’ve been swilling and gargling with a capful of this fluorescent liquid for more than a century, says award-winning dentist and practice owner Dr Jacy Cleal.
“The original ‘Listerine’ was formulated back in 1879 as a surgical antiseptic, but it didn’t become a household name until the 1920s, when it was repackaged as a cure for ‘chronic halitosis’
“Its advertising featured forlorn young men and women, undone by their partners’ bad breath!”
Along with its present-day halitosis-fighting powers, Dr Cleal says there are proven clinical benefits to mouthwash too and believes the studies and recent press coverage of health risks should be consumed with caution and context.
“The research found an increase in opportunistic bacteria associated with periodontal disease, oesophageal cancer, colorectal cancer and systemic disease. There is also emerging evidence that oral bacteria may migrate to the gut, potentially contributing to inflammatory bowel disease, colorectal cancer and systemic inflammation.
“But context matters,” stresses Dr Cleal. “Alcohol-based mouthwash may be a contributing factor alongside smoking, heavy drinking or a poor diet, but research does not suggest it causes cancer in isolation. Extensive long-term use would be required for any risk to be meaningful.”
Considering a lack of definitive long-term population data, Dr Cleal adds: “Given what we do know about the oral-systemic health connection, and the particular vulnerability of older patients’ oral health, if an alcohol-free alternative delivers the same result, the choice seems obvious.”
Coates explains that brushing alone is usually insufficient for optimal plaque control, and using an effective mouthwash as part of a good oral hygiene routine is important.
A dental rinse, however, should never be considered a replacement for brushing and flossing, says Coates, but it can be a valuable addition to prevent decay and gum disease, while freshening breath.
“Regular use supports healthy gums, and mouthwash containing essential oil formulas (eucalyptol, menthol, methyl salicylate and thymol) may disrupt bacterial cell walls, helping to clean hard-to-reach areas and aiding the reduction of plaque and bleeding gums,” Coates explains. “Some formulas can also protect against the germs that cause bad breath for up to 12 to 24 hours.”
With more than 100 varieties of mouthwash on offer at supermarkets, chemists and pharmacy websites, which should we be using to best care for our oral health?
“It depends entirely on what you’re trying to achieve,” says Dr Cleal. “For patients with early-stage gum disease, a short course of chlorhexidine mouthwash – such as Corsodyl 0.2% – can be genuinely helpful.
“Evidence has shown it reduces plaque build-up in the first weeks or months of use for people with mild gum disease, and it carries the highest clinical evidence for treating gum disease. However, it is for short-term use only, as it will cause staining if used for more than a few weeks.”
Coates adds that alcohol-free anti-plaque rinses containing cetylpyridinium chloride (CPC) or essential oils are gentle on sore gum tissue and safe for long-term use.
Both Cleal and Coates agree that a fluoride mouthwash is effective at helping to prevent decay, reducing the risk of gum disease and strengthening enamel.
“For older people with active cavities, the government’s Delivering Better Oral Health (DBOH) guidelines recommend a daily fluoride rinse (0.05% NaF; 230ppm fluoride) until the dental caries (cavities) risk is reduced,” says Coates.
“For bad breath specifically, rinses containing essential oils or zinc target the volatile sulphur compounds responsible for odour and have good clinical backing,” Dr Cleal explains.
Children aged under six should never use a dental rinse, says Dr Cleal, and people with certain conditions are advised to omit mouthwash from their routines.
She advises: “People with ‘dry mouth’ – including those on certain medications, undergoing radiation treatment, or with conditions such as diabetes, high blood or Sjögren’s syndrome – are better off avoiding alcohol-based mouthwash, as are people with a history of alcohol dependency.
“And on chlorhexidine, using it for longer than four weeks leads to tooth staining and calculus build-up (tartar),” adds Dr Cleal. “UK guidance already restricts use to 30 days at a time. If you’ve been using Corsodyl daily for months without guidance from your dentist, please stop and seek advice.”
Yes, says Dr Cleal: “This is something I feel strongly about and the evidence is becoming hard to ignore. The oral microbiome helps us digest food and keep our mouths healthy.
“Changes to its composition were linked to periodontal diseases and some cancers in the Journal of Medical Microbiology, which found that after three months of daily Listerine Cool Mint use, two species – Fusobacterium nucleatum and Streptococcus anginosus – were significantly more abundant. Both have been linked to gum disease, oesophageal cancer, and colorectal cancer.
“The study also noted a reduction in Actinobacteria, beneficial bacteria involved in the nitrate-nitrite-nitric oxide pathway, which helps regulate blood pressure and links the oral microbiome to cardiovascular health,” Dr Cleal continues.
“The mouth is not meant to be sterile. A balanced oral microbiome is genuinely protective, and alcohol-based rinses that indiscriminately destroy both good and bad bacteria disrupt that balance.”
However, Coates takes an alternative stance: “Concerns about oral microbiome disruption are based on emerging research showing that strong antimicrobial mouthwashes can alter the balance of oral bacteria. However, researchers generally describe the long-term health implications as uncertain and still under investigation.”
“Yes, but with consideration,” says Dr Cleal. “Rinsing with a gentle fluoride or antiseptic mouthwash helps care for the gum tissue and any remaining natural teeth.
“For the dentures themselves, soaking is more effective. Chlorhexidine solution has shown good activity against Candida albicans and Streptococcus mutans, the organisms associated with denture-related infections, outperforming both mechanical brushing and effervescent tablets.”
Dr Cleal advises caution for those suffering with dry mouth: “The condition is more common with age and with denture wear. An alcohol-free antibacterial rinse is a far kinder choice than an alcohol-based one.”
Coates recommends that denture wearers should consult a dental professional about the most suitable mouthwash for their needs and ensure a denture cleansing routine is established.
Halitosis usually originates from bacteria on the back of the tongue, between the teeth or from early gum disease. Mouthwash masks the smell – it doesn’t solve the problem, explains Dr Cleal. She offers the following tips for fresh breath:
The risk and occurrence of gum disease increases with age, says Dr Cleal. “It affects the majority of UK adults to some degree and significantly rises in later life.
“It is linked to cardiovascular disease, diabetes, and cognitive decline including dementia. Bleeding gums are not normal. If your gums bleed when you brush, please see your dentist.”
Oral cancer is another condition that we should be aware of as we age. “Survival rates improve dramatically with early detection, which is why every routine examination should include a screening check,” urges Dr Cleal.
“Key risk factors are smoking, heavy alcohol consumption, and certain strains of HPV. Any unexplained ulcer lasting more than two weeks, or any unusual red or white patch or lump, should be investigated without delay.”
Cleal adds: “The NHS and DBOH guidelines confirm there is little evidence that mouthwash use increases oral cancer risk. The concern lies in the longer-term, systemic effects of microbiome disruption, which is reason enough – particularly for older patients – to choose products carefully and keep up with regular exams and hygiene appointments.”
Dr. Jacy Cleal is a dentist and practice owner at Windmill Dental Practice, 202 Old Shoreham Road, Southwick, West Sussex.
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