Bad breath (halitosis): where it comes from, whether it can come from the stomach and how to get rid of it

Where does bad breath come from?

Bad breath most often arises when anaerobic bacteria in the mouth produce volatile sulphur compounds, mainly hydrogen sulphide and methyl mercaptan. A 2016 review indicates that the main place where this happens is the coating on the upper surface of the tongue, followed by the pockets around diseased gums.

Halitosis is common: a pooled analysis of 13 studies put it at 31.8%, roughly one person in three, although the results of individual studies varied widely.

A passing smell after strong-smelling or spicy food, alcohol or a cigarette is not the same as chronic halitosis, although the NHS, the UK’s public health service, lists these causes side by side. The same list includes fasting and crash diets, dental problems, a dry mouth and reflux.

Bad breath: causes in the mouth and beyond

The causes of bad breath divide into those in the mouth and those outside it, and the former clearly predominate. In a Belgian bad breath clinic, among 2,000 patients, a cause in the mouth was found in 76%: tongue coating alone in 43%, gingivitis or periodontitis in 11%, and both factors together in 18%.

In 16% of this clinic’s patients no unpleasant smell was confirmed (pseudo-halitosis or fear of bad breath), and ear, nose and throat and other causes outside the mouth accounted for 4%. A 2016 review states that at least 90% of cases originate in the mouth.

Tongue coating: why is it so often behind the smell?

Tongue coating is a deposit on the upper surface of the tongue which, according to a 2016 review, is the dominant factor in bad breath. In the Belgian clinic it was the only cause found in 43% of patients, and in a further 18% it occurred together with gum disease.

The NHS recommends cleaning the tongue as a daily part of hygiene for bad breath. However, the current 2019 Cochrane review found only a small improvement in odour as assessed by a dentist after mechanical tongue cleaning and judged this evidence very uncertain, so tongue cleaning is one element, not a solution on its own.

Clean the tongue gently, with a scraper or a brush, without injuring the mucous membrane. A coating that does not come off, changes colour or comes with pain or burning of the tongue is worth showing to a dentist.

Can bad breath come from the gums?

After tongue coating, gum disease is the second most common cause of bad breath in the mouth. A 2017 meta-analysis reports that people with periodontitis have about three times the odds of halitosis (odds ratio 3.16).

Deposits in deepened pockets around the teeth lie below the gum, out of reach of a toothbrush and mouthwash, so in this situation more thorough brushing alone is not enough. Tartar and deposits need to be removed at the surgery, and in periodontitis periodontal treatment is needed; its stages are described in the article on periodontitis and bleeding gums.

Signs that the source lies in the gums include bleeding when brushing, swelling, receding gums or loose teeth. The NHS lists these symptoms as a reason to see a dentist.

Dry mouth and bad breath

A dry mouth encourages bad breath, and medicines are one of its possible causes. A 2013 review lists medicine-induced dry mouth among the factors contributing to halitosis, and the NHS includes a dry mouth in its list of causes of bad breath.

If you suspect that your dry mouth is linked to medicines, do not stop taking them on your own. Tell the doctor who prescribed them and your dentist, so that together they can decide what can be changed.

Bad breath and the stomach: when does the cause lie outside the mouth?

Bad breath rarely comes from the stomach: ear, nose and throat and other causes outside the mouth were found in 4% of patients at the Belgian clinic. A 2013 review lists among them diseases of the nose and throat (sinusitis, tonsillitis, tonsil stones), lung infections, reflux and Helicobacter pylori infection, liver or kidney failure, diabetic ketoacidosis and a rare metabolic disorder, trimethylaminuria.

If the dentist finds no cause in the mouth, the next step is a GP or an ENT specialist. It is worth mentioning heartburn, belching, recurrent throat or sinus infections and any medicines you take.

A fruity smell on the breath, like nail polish remover, together with intense thirst, frequent urination, vomiting, drowsiness or deeper breathing than usual, may mean ketoacidosis, even in someone who does not know they have diabetes. This is an emergency: the NHS advises urgent hospital care in this situation, which in Poland means the hospital emergency department (SOR) or calling 112, the emergency number.

The reverse also happens: someone is convinced they have bad breath, although an examination does not confirm it. At the Belgian clinic this applied to 16% of patients, and the smell there was assessed objectively, by the sense of smell of a trained person (organoleptic assessment) and with a sulphur compound meter.

How do you get rid of bad breath?

You get rid of bad breath by removing its source, not by masking the smell. When the cause is in the mouth, the basis is the daily hygiene recommended by the NHS, summarised in the list below; mouthwashes and chewing gum do not replace brushing.

A 2019 Cochrane review (44 studies) did not find that any treatment for bad breath, including mouthwashes, toothpastes and tongue cleaning, was clearly more effective than the others, and the certainty of all the results was low or very low. If home hygiene has not helped after a few weeks, an examination is a more sensible step than switching mouthwash.

• Brush your teeth and gums gently, at least twice a day for 2 minutes, with fluoride toothpaste.
• Clean your tongue every day with a scraper or a brush.
• Clean between your teeth every day with floss or interdental brushes.
• If you wear a denture, clean it every day as your dentist advises.
• Do not smoke, and cut down on alcohol and on sugary food and drinks.
• After a strong-smelling meal, have sugar-free mints or chewing gum.
• You can try an antibacterial mouthwash or toothpaste, but as an addition, not instead of brushing.

When should you see a dentist about bad breath, and when a doctor?

It is worth seeing a dentist about bad breath if it does not go away after a few weeks of careful hygiene at home, and sooner if it comes with other symptoms. In the situations in the list, contact a dentist or doctor.

• Bleeding, swollen or painful gums, toothache or loose teeth: see a dentist.
• A denture that rubs or is hard to keep clean: see a dentist.
• Sore throat with fever, recurrent sinusitis or tonsillitis: see a GP or an ENT specialist.
• Frequent heartburn or sour belching: see a GP.
• Fruity-smelling breath with intense thirst, vomiting, drowsiness or deeper breathing: hospital emergency department (SOR) or 112.

How it works at DentalBlue

With bad breath, the starting point is an examination of the teeth, gums and tongue. At DentalBlue in Białystok, a “Wizyta bez bólu” (visit without pain) includes a panoramic X-ray, a consultation, an examination and a written treatment plan (300 zł in the clinic’s price list). When deposits or the gums turn out to be the source, the price list includes “Kompleksowa higienizacja (skaling, piaskowanie, fluoryzacja)” (comprehensive hygiene treatment: scaling, air polishing, fluoride) at 350 zł and “Konsultacja periodontologiczna” (periodontal consultation) at 300 zł. The final scope and cost are agreed at the visit, and prices may change.