Despite being a regular part of dental hygiene routines for a third of adults, experts are cautioning that mouthwash may be largely unnecessary for many individuals and could potentially do more harm than good. With an estimated £224 million spent annually on mouthwash in the UK, much of this expenditure might be ineffective. While mouthwash contains beneficial ingredients like fluoride and antibacterial chemicals, dentists assert it is generally less effective than brushing at tackling common issues such as gum disease and tooth decay.

Moreover, numerous studies have suggested links between certain mouthwashes and serious health conditions, including oral cancer and heart disease. Professor David Conway of the University of Glasgow Dental School advises against the routine use of mouthwash, stating it is not required for general oral hygiene.

The UK faces significant dental problems, with recent government surveys indicating a rise in tooth decay and gum disease, affecting two-fifths of adults with 'obvious decay' in at least one tooth. These issues predominantly stem from plaque—a sticky film of bacteria, food, and saliva that forms along the gum line, leading to inflammation (gingivitis) and bleeding. Plaque bacteria also produce acids from sugars, damaging enamel and causing cavities.

A key selling point for many mouthwashes is the presence of sodium fluoride, which strengthens tooth enamel. However, Professor Conway explains that it doesn't provide the same protection as proper brushing with toothpaste, which adheres better to teeth. The common practice of rinsing with water immediately after brushing washes away beneficial fluoride. Using mouthwash at this point merely replaces some of the rinsed-away fluoride. The best advice is to spit out excess toothpaste after brushing but to avoid rinsing, thereby retaining the fluoride in the mouth without the need for mouthwash.

Many types of mouthwash contain up to 27 percent alcohol. Professor Conway notes that while alcohol acts as an antiseptic, it is also a carcinogen known to cause cancers of the mouth, throat, and larynx. A 2014 study by the International Agency for Research on Cancer linked mouthwash to oral cancer, specifically among individuals who used it more than three times a day.

Other bacteria-killing ingredients include chlorhexidine gluconate, a powerful antiseptic found in products like Corsodyl. Professor Conway warns that such products should only be used after consulting a dentist and typically for short periods. Chlorhexidine is used to treat bacterial gum disease, oral thrush (a fungal infection), and mouth ulcers. Routine use is generally unnecessary for most people outside of specific short-term treatments.

Studies have also indicated a link between mouthwash containing chlorhexidine and cetylpyridinium chloride (a milder antiseptic) and an increased risk of heart disease. The theory suggests these compounds, while destroying harmful bacteria, also eliminate beneficial bacteria essential for converting nitrates from foods like salads and vegetables into nitric oxide, which is vital for cardiovascular regulation.

Dr. Praveen Sharma, associate professor at the University of Birmingham and scientific adviser to the British Dental Association, highlights the emerging understanding of the oral microbiome and cautions against indiscriminately eliminating its diverse bacteria. He also expresses concern about using mouthwash regularly to treat halitosis (bad breath), explaining that it often masks symptoms without addressing underlying causes like gum disease, akin to blasting a room with air freshener.

However, mouthwash does have value as an add-on in specific scenarios. For individuals at a higher risk of tooth decay, a fluoride mouthwash can be beneficial. These individuals should brush with fluoride toothpaste in the morning and evening, then add a mouthwash rinse in the middle of the day. For the majority, however, mouthwash has no significant role and should never be considered a substitute for twice-daily brushing.

For those seeking alternatives to mouthwash for maintaining fresh breath, several methods are recommended. Staying hydrated is crucial, as saliva naturally helps to wash away bacteria and food particles. A 2021 Korean study confirmed that dehydration is linked to worse breath, reduced saliva production, and higher levels of foul-smelling sulphur compounds. Chewing sugar-free gum, especially those containing xylitol, can boost saliva production. A 2017 review in the Journal of Breath Research concluded that chewing gum can reduce compounds associated with bad breath. Incorporating crunchy foods like apples, carrots, and celery into the diet can help clean the mouth during eating. Green tea also contains compounds believed to reduce sulphur-producing bacteria.

Conversely, certain habits can exacerbate bad breath. Experts advise against acidic drinks such as coffee and energy beverages. Skipping meals can also worsen the problem by leading to a dry mouth.