It is regularly used by a third of adults. But although mouthwash is marketed as a key part of everyday dental hygiene, experts have told the Mail that for many people it is unnecessary – and may even be doing more harm than good.
And at a time of tightened household budgets, they warned that much of the estimated £224million spent on mouthwash in the UK each year may, quite literally, be money down the drain.
Despite containing beneficial ingredients such as fluoride and antibacterial chemicals, dentists say mouthwash is generally less effective at tackling gum disease and tooth decay than brushing.
Meanwhile, numerous studies have suggested links between some mouthwashes and serious conditions, including oral cancer and heart disease.
Professor David Conway, of the University of Glasgow Dental School, says: ‘I would not advise routine use of mouthwash, full stop. It isn’t needed as part of general oral hygiene.’
The UK has severe dental problems, with the Government’s latest Adult Oral Health Survey showing tooth decay and gum disease have increased in recent years, with two-fifths of adults now having ‘obvious decay’ affecting at least one tooth.
The most frequent issues are caused by the build up of plaque – a sticky film of bacteria, food and saliva that forms along the gum line – which can lead to inflammation of the gums, known as gingivitis, and bleeding when brushing. Bacteria in plaque also feed on sugars from food, releasing acids that can damage enamel – the hard protective coating of the teeth – leading to cavities and decay.
Mouthwash can contain up to 27 per cent alcohol and, used straight after brushing, can wash away fluoride from toothpaste
While a key selling point for many mouthwashes is that they contain sodium fluoride, a chemical that strengthens tooth enamel, Prof Conway explains that it does not provide the same protection as brushing properly with toothpaste, which foams and adheres better to the teeth.
The problem, he says, is that too many people rinse their mouth with water immediately after brushing, which simply washes away the fluoride.
He adds: ‘At that point, using mouthwash only replaces some of the fluoride you’ve just rinsed away. The best advice is to spit out excess toothpaste after brushing, but don’t rinse. That keeps the fluoride from the toothpaste in your mouth, without any need for mouthwash.’
Many types of mouthwash also contain up to 27 per cent alcohol.
Prof Conway says: ‘It’s a good antiseptic that kills off bacteria. But it’s also a carcinogen – known to cause cancers of the mouth, throat and larynx.’
Prof David Conway says many types of mouthwash can be cancer-causing
A study by the International Agency for Research on Cancer in 2014 linked mouthwash to oral cancer, although only among people who used it more than three times a day.
Other bacteria-killing ingredients in mouthwash include chlorhexidine gluconate – a powerful antiseptic found in products such as Corsodyl.
Prof Conway warns these should only be used after consultation with a dentist, and typically only for short periods.
Chlorhexidine treats bacterial gum disease, oral thrush – a fungal infection – and mouth ulcers.
Prof Conway says: ‘Apart from short-term treatment for specific conditions, it shouldn’t be routinely used. For most people, it isn’t necessary.’
Studies have also linked mouthwash containing chlorhexidine and another, milder, antiseptic called cetylpyridinium chloride to an increased risk of heart disease. The theory is that while these compounds destroy harmful bacteria, they also kill off bacteria that help convert nitrates from foods such as salad and vegetables into nitric oxide, which the body uses to regulate the cardiovascular system.
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Dr Praveen Sharma, associate professor at the University of Birmingham and scientific adviser to the British Dental Association, says: ‘We’re just starting to learn the role of different bacteria in the oral microbiome, so maybe we shouldn’t be indiscriminately nuking them.’
He also warns there is particular concern about the regular use of mouthwashes to treat halitosis.
He says: ‘Bad breath may be caused by gum disease, in which case using mouthwash is effectively just blasting it with air freshener – it’s masking the symptom without treating the cause.’
However, mouthwash does have value as an add-on for some.
He adds: ‘For those with a higher risk of tooth decay, a fluoride mouthwash can be useful.
‘They should be brushing with fluoride toothpaste in the morning and evening, but then adding a rinse with mouthwash in the middle of the day.
‘For most, mouthwash doesn’t have a role to play. And it certainly shouldn’t be used as a substitute for twice-daily brushing.’
The easiest ways to avoid bad breath
There are alternatives to mouthwash to keep bad breath at bay. One way is to stay hydrated, as saliva naturally helps to wash away bacteria and leftover food particles.
A 2021 Korean study proved this by examining dehydrated, normally hydrated and over-hydrated volunteers. They found dehydration was linked to worse breath, lower saliva production and higher levels of sulphur compounds – the chemicals responsible for foul breath.
Experts say another way to boost saliva is chewing sugar-free gum, particularly those with xylitol, a natural sugar alcohol. A 2017 review in the Journal of Breath Research looked at multiple studies on chewing gum and concluded it can reduce compounds associated with bad breath.
Crunchy food helps too. Apples, carrots and celery can help to clean the mouth as you eat. Also, green tea contains compounds believed to reduce levels of the sulphur-producing bacteria that are linked to bad breath.
Experts add that acidic drinks like coffee and energy beverages can make the problem worse. Skipping meals can also compound the dilemma by drying out the mouth, say health experts.
