The hidden causes of your bad breath - and EXACTLY how to beat it. Plus how to tell if it's a sign of a serious lurking health problem, reveals DR PHILIPPA KAYE

The patient – let’s call her Melanie – in my consulting room looked absolutely mortified.

‘What seems to be the problem,’ I asked. Melanie blushed and mumbled something from behind her hand while looking at the floor.

Now I’m fairly used to this. It’s not unusual for patients to be shy about a problem, particularly if it’s relating to an intimate issue. But that wasn’t the case here. When she finally seemed to calm down a bit, she whispered: ‘It’s my breath.’

And then it all came tumbling out. Melanie had just started a new job and was due a review with her boss. He had awkwardly explained that other staff had complained about her bad breath.

She’d left the meeting in tears, seen her dentist the same day and been told her teeth were fine – but she should book in with her GP.

The first thing I told her is that bad breath – or halitosis, as doctors call it – is astonishingly common.

Surveys suggest up to one in four adults suffer from it at any given time and, while rarely dangerous, it can be devastating to confidence.

Surveys suggest as many as half of us feel self-conscious about our breath, at least occasionally.

Yet simple steps – good oral hygiene, adequate hydration, treating nasal or digestive problems and quitting smoking – solve the vast majority of cases.

Embarrassing though it was for Melanie, being told the truth allowed her to fix the cause.

And that, to me, is always preferable to not knowing – because bad breath isn’t just a social nuisance, it’s often your body’s way of asking for help.

Persistent bad breath can be a sign that something else is going on, and should always be checked out by a doctor.

Here’s everything you need to know if you’re worried you might suffer with the problem.

Most cases of halitosis originate in the mouth – which is hardly surprising. Bits of food trapped between teeth feed bacteria that release foul-smelling sulphur compounds. If you don’t brush effectively, or skip flossing, those bacteria thrive.

Gum disease and tooth decay are also major culprits – and in the worst cases, small abscesses under the gum can produce a distinctly putrid smell.

According to the Adult Oral Health Survey of 2021, around one in four British adults has untreated tooth decay, while roughly 40 per cent show signs of gum disease. With figures like that, it’s little wonder bad breath is so common.

Preventing it is simple. Brush twice daily with a fluoride toothpaste – ideally before breakfast and again before bed – and use floss or interdental brushes at least once a day, making sure to clean along the gum line.

Many dentists also recommend brushing before eating. It sounds counterintuitive but food and drink can raise the mouth’s acidity, temporarily softening enamel, so brushing afterwards can cause damage.

Gently brushing the tongue for about 30 seconds each time you clean your teeth is another top tip. Large amounts of bacteria live on the tongue, so doing this can significantly reduce bad breath.

And although it may feel odd at first, avoid rinsing with water after brushing – leaving a thin film of fluoride on the teeth allows it to keep working long after you have finished.

Electric toothbrushes are more effective at removing plaque than manual ones, and regular dental check-ups are essential.

Sometimes the smell comes from deeper in the throat. The tonsils – pads of immune tissue at the back of the mouth – can develop tiny, whitish lumps called tonsil stones or tonsilloliths.

These form when debris such as food particles, mucus and dead cells get trapped in the tonsil’s crevices and calcify.

They’re more common than you might think – studies suggest up to 10 per cent of adults have them at some point, although many never realise it.

The bacteria involved release volatile sulphur compounds that smell like rotten eggs.

Some doctors say they are seeing more cases of tonsil stones – and suspect rising obesity rates could be playing a part.

Obesity is linked to enlarged tonsils, chronic throat inflammation and mouth-breathing – all of which may make the small crevices in the tonsils more prone to trapping debris.

However, there is little firm evidence to confirm this. Studies show obesity can increase the risk of tonsillitis and tonsil enlargement, particularly in children, but there is no clear proof that it directly raises the likelihood of tonsil stones forming.

It’s also possible that doctors are simply spotting them more often. Better imaging and greater awareness – along with the fact that fewer people now have their tonsils removed – could explain the apparent rise.

In recent years, tonsil stones have become a social media trend, with millions watching videos of people squeezing or flushing them out at home.

ENT doctors say they often see patients who have tried this – sometimes with painful or even bleeding tonsils as a result.

While some NHS guidance notes that it may be possible to gently ease out small stones with a cotton bud or low-pressure water flosser, the safest option is to see your GP.

They can rule out other causes of bad breath, advise on self-care and, if needed, refer you to an ear, nose and throat specialist.

Gargling with warm salt water or mouthwash may help to dislodge stones naturally and keep bacteria at bay.

Good dental hygiene – brushing twice daily, cleaning the tongue and flossing – also helps to prevent them forming in the first place.

The NHS does not routinely offer tonsil removal for tonsil stones, except in exceptional cases where symptoms are persistent and self-care has failed.

The nose, sinuses and throat are all connected, so problems higher up can easily affect the breath.

Sinusitis – inflammation or infection of the sinus cavities – causes mucus to drip down the back of the throat, a phenomenon known as post-nasal drip. This thick mucus provides the perfect food for bacteria, producing the sour, stale smell many people notice during a bad cold.

In chronic cases it can linger for weeks or even months after other symptoms have cleared.

Chronic sinusitis affects roughly one in ten adults.

It often develops after a lingering viral infection, or when the delicate tissue lining the sinuses becomes chronically inflamed.

In some people this is due to allergies such as hay fever or dust mite sensitivity, in others, nasal polyps – small growths that block drainage – or a deviated septum prevent mucus from clearing properly.

Even simple nasal congestion can make matters worse by forcing you to breathe through your mouth. This dries out saliva, which would normally neutralise bacteria and wash away the debris.

Treat the underlying congestion. Saline nasal sprays can help clear mucus, while antihistamines may be useful if allergies are the cause.

Steroid nasal sprays – available over the counter and on prescription – can reduce inflammation and swelling.

Staying well hydrated thins mucus, making it easier to clear, and regular hand-washing or avoiding known triggers can help reduce the risk of recurrent sinus infections. If symptoms last more than a few weeks or are accompanied by facial pain, pressure or a persistent blocked nose, see your GP for assessment.

Saliva is one of the mouth’s unsung heroes. It washes away food debris, neutralises acid and keeps bacterial growth in check. But when saliva production drops – a condition called xerostomia – bacteria multiply and the breath quickly suffers.

Dry mouth becomes more common with age and affects up to one in five adults. It can be triggered by medications such as antihistamines, antidepressants and diuretics, which all reduce saliva flow as a side effect.

Hormonal changes around the perimenopause and menopause can also dry out the mouth by affecting glands producing saliva.

Dehydration, mouth-breathing, smoking and alcohol – all of which further reduce saliva – can make matters worse.

In severe cases the tongue may feel sticky or sore, swallowing can become difficult and the inside of the cheeks may even crack or peel.

Sip water frequently, chew sugar-free gum to stimulate saliva and regularly use an alcohol-free mouthwash.

Artificial saliva sprays and gels available at pharmacies can also help coat and soothe the mouth.

Avoid smoking and try to limit caffeine and alcohol – both are diuretics, meaning they make you urinate more and become dehydrated faster.

If you suspect medication may be the cause, ask your GP or pharmacist whether alternatives exist, or whether doses can be adjusted.

The mouth and throat connect to the stomach, so anything that causes acid or partially digested food to rise can taint the breath.

This is common in people with gastro-oesophageal reflux disease (GERD), which affects around one in five UK adults.

Typical symptoms include heartburn, regurgitation, a sour taste in the mouth or a persistent cough – and, yes, bad breath.

The smell comes from stomach acid and digestive gases creeping up the oesophagus, as well as irritation of the throat and mouth lining, which encourages bacterial growth.

In rarer cases, certain bacteria in the stomach such as Helicobacter pylori – the bug linked to stomach ulcers – can also produce unpleasant odours.

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If reflux or indigestion are continuing problems, your doctor may test for this.

What you can do: To help reduce symptoms of acid reflux, consider reducing or avoiding rich and spicy foods, caffeine and alcohol – and quitting smoking.

These items can relax or weaken the lower oesophageal sphincter, the muscle that prevents stomach acid from flowing back up into the oesophagus.

Sensitivity to these triggers can vary from person to person.

Avoid lying down straight after eating and try smaller, more frequent meals.

Over-the-counter antacids can bring short-term relief, while longer term your GP may prescribe proton-pump inhibitors (PPIs) to reduce acid production.

Maintaining a healthy weight and elevating the head of the bed slightly can also make a noticeable difference.

Occasionally, halitosis can be a sign of an underlying medical condition. Liver disease can cause a smell known as fetor hepaticus – often described as musty, sweet or sulphurous – due to a build-up of toxins the liver can’t clear.

Kidney failure can lead to a urine-like odour called uraemic fetor, while uncontrolled diabetes can give the breath a fruity or ‘pear-drop’ scent.

Diabetes occurs when the body can’t use glucose properly for energy. Instead, it begins breaking down fat, releasing chemicals called ketones into the blood and breath.

The condition can cause dehydration, nausea, vomiting and rapid breathing, and requires urgent medical attention.

A rare inherited disorder called trimethylaminuria, or ‘fish-odour syndrome’, occurs when the body can’t break down the compound trimethylamine, leading to a smell of rotting fish on the breath, sweat and urine.

What you can do: If bad breath is accompanied by weight loss, fatigue, nausea or a metallic taste, see your GP for blood and urine tests. Treating the underlying condition is key and in most cases, once it’s managed, the smell disappears too.