It’s a habit 60 percent of us undertake at least once a week.
Many see mouthwash as an essential part of oral hygiene, killing bacteria in the mouth to banish bad breath and help prevent tooth decay.
But dentists are now warning that, for most people, the habit is unnecessary – and may even be doing more harm than good.
Dr David Conway, from the University of Glasgow Dental School, previously said: ‘I would not advise routine use of mouthwash, full stop.
‘It isn’t needed as part of general oral hygiene.’
Researchers warn that there is no good evidence that mouthwash is more effective than tooth brushing in preventing cavities or solving bad breath.
At the same time, some small studies have warned that it could raise blood pressure – or even put users at a higher risk of cancer.
So, should you really keep using mouthwash regularly?
Experts are warning people against using mouthwash regularly (stock image)
To maintain mouth health, doctors recommend brushing teeth at least twice a day using a toothbrush and toothpaste that contains sodium fluoride, which strengthens enamel and prevents cavities.
The mechanical action of the toothbrush removes bacteria that could cause cavities and any food they could colonize, raising the risk of tooth decay. The foam formed during brushing also helps fluoride adhere better than if it were in mouthwash.
There are two main types of mouthwash: Therapeutic mouthwashes, which contain active ingredients that kill bacteria and help with common dental issues such as bad breath, gum disease and tooth decay, and cosmetic mouthwashes, which temporarily mask bad breath and leave a pleasant taste but do little more.
While cosmetic mouthwashes simply mask a problem such as bad breath, experts warn that therapeutic ones could do damage to your health because of the disruption to the mouth microbiome.
The mouth is home to billions of bacteria that help boost oral health. But when a mouthwash is used, both the ‘bad’ and ‘good’ bacteria are swept away, raising the risk of complications.
According to Dr Joanna L’Heureux, a public health expert in the UK, one of the main roles of bacteria in the mouth is to create chemicals to help manage blood pressure, with high blood pressure being one of the most common health conditions in the US.
Bacteria at the back of the tongue convert nitrate in our food, from sources such as leafy greens, into nitrite. The body absorbs this and converts it into nitric oxide, a compound that is essential for helping blood vessels dilate to lower blood pressure.
One small trial published in 2020 tracked 36 healthy adults in Britain who rinsed their mouths twice a day for seven days with a placebo mouthwash, and then did the same with a therapeutic mouthwash.
It found there was a ‘major shift in the salivary microbiome’ of the mouth and a major drop in the population of bacteria needed to maintain healthy blood pressure.
Many use mouthwash to help reduce their risk of dental cavities
Another small study of 19 healthy volunteers found that adults who used mouthwash for seven days saw a small increase in blood pressure and reduced levels of nitrite.
In another trial involving 15 adults who already had high blood pressure, three days of using mouthwash was found to further increase blood pressure.
In these studies, the mouthwashes used contained chlorhexidine, a strong antiseptic available via prescription in the US that is only recommended for short-term use in people with gum disease or other dental problems.
Some experts have warned this may also raise the risk of heart disease because high blood pressure is known to cause more damage to blood vessels, raising the risk of suffering from heart problems.
There is also evidence to suggest that using a mouthwash may raise your risk of cancer.
Many mouthwashes contain up to 27 percent alcohol, which helps to kill off bacteria but is also a known carcinogen – linked to cancers of the mouth, throat and larynx.
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.
When it comes to treating bad breath, experts also warn there is particular concern over using mouthwash to do this.
Dr Praveen Sharma, a dentist in the UK and adviser to the British Dental Association, said: ‘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.’
So, how often is it safe to use mouthwash?
Dr Purnima Kumar, an oral medicine expert at the University of Michigan, previously told the New York Times that if someone uses mouthwash occasionally, such as once a week or once a month, it is unlikely to do damage to their oral health.
But she warned that using mouthwash daily for months or years on end could lead to various complications.
She said: ‘Do I have a bottle of mouthwash next to my toothbrush? Absolutely. But do I use it every day? Certainly not.’

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