Bad Breath: Real Causes, Remedies That Actually Work and When to See Your Dentist

What is halitosis and how common is it?

Halitosis is the presence of an unpleasant odour in exhaled breath. It is one of the most common oral complaints: estimates suggest that between 25 and 30% of the population suffers from it chronically, with significant social consequences. It is also one of the hardest problems to notice in oneself: we adapt to our own smell, and bad breath often goes undetected through self-assessment.

There are two main types: true halitosis (measurable with clinical instruments or perceptible to an external observer) and halitophobia, the subjective perception of having bad breath in the absence of an organic cause. In both cases the concern is real and deserves attention.

The causes: almost always the mouth, not the stomach

Common wisdom says bad breath comes from the stomach. The data says otherwise: between 85 and 90% of halitosis cases have an oral origin. The cause is almost always the presence of anaerobic bacteria that metabolise organic residues (proteins, desquamated cells, food particles) and produce volatile sulphur compounds: hydrogen sulphide, methyl mercaptan, dimethyl sulphide. These compounds generate the characteristic odour.

The main oral causes include:

• Bacterial accumulation on the tongue, particularly on the posterior third, where bacteria hide between the filiform papillae
• Periodontitis: periodontal pockets are ideal anaerobic environments for the bacteria responsible for halitosis
• Deep cavities and teeth with pulpitis or pulp necrosis
• Dentures, orthodontic appliances or bridges that are poorly cleaned and retain bacterial residues
• Dry mouth (xerostomia): saliva plays a fundamental role in mechanically washing away bacteria; when saliva is insufficient, bacteria proliferate
• Food residues trapped between teeth due to lack of flossing

The tongue: the main overlooked culprit

The back of the tongue is the primary source of oral halitosis in approximately 60% of cases. Its irregular surface, rich in filiform papillae, creates an ideal environment for the accumulation of desquamated cells, food residues and anaerobic bacteria. The whitish or yellowish coating visible on the posterior third of the tongue is precisely this bacterial build-up.

Paradoxically, it is also the easiest cause to address: daily tongue cleaning with a soft toothbrush or a dedicated tongue scraper measurably reduces the production of volatile sulphur compounds. It should be done every morning, working from the back towards the front with a gentle touch to avoid triggering the gag reflex.

How to recognise and measure it

Self-diagnosis is often inaccurate. Some practical methods to get an idea:

• Run dental floss between your back molars, let it dry for 10 seconds and smell it
• Lick the back of your wrist, wait for it to dry and smell it
• Ask someone you trust for a direct assessment — the most accurate non-professional method available

In the practice, the dentist can measure halitosis using a halitometer (sulphide monitor), an instrument that quantifies volatile sulphur compounds in exhaled air. The clinician's organoleptic assessment remains the primary reference, complemented by examination of the tongue, gums and saliva.

When bad breath does not respond to home hygiene

If bad breath persists despite regular brushing, flossing and tongue cleaning, it is a signal that there is an underlying cause that home remedies cannot resolve. The most common situations are:

• Active periodontitis: periodontal pockets cannot be reached by a toothbrush and require professional debridement. Every additional millimetre of pocket depth means a more anaerobic environment and a greater sulphide-producing bacterial load. Read more in our article on periodontitis.
• Hidden cavities: an interproximal cavity (between teeth) may be invisible to the naked eye but acts as a continuous source of bacteria and necrotic tissue
• Chronic dry mouth: caused by medications (antihistamines, antidepressants, diuretics), radiotherapy or conditions such as Sjögren's syndrome. Without saliva, there is no natural mechanical cleansing
• Contaminated dentures: porous acrylic dentures can absorb bacteria and odours over time; they require professional cleaning and periodic replacement

Remedies: what actually works

Not all commonly cited remedies have the same effectiveness. Here is a realistic overview:

What genuinely helps

• Regular professional cleaning every 6 months: removes subgingival tartar, the main bacterial reservoir, and resets the level of build-up that no toothbrush can reach. Read why professional cleaning every 6 months matters.
• Daily tongue cleaning with a scraper or soft toothbrush
• Dental floss or interdental brushes every day: remove residues between teeth where a toothbrush cannot reach
• Adequate hydration: drinking water regularly helps maintain saliva production
• Mouthwashes containing chlorhexidine or cetylpyridinium chloride (CPC): reduce bacterial load, but should be used on the dentist's advice and for limited periods, not as a permanent habit

What does not solve the problem

• Chewing gum and mints: mask the odour for a few minutes but do not eliminate bacteria
• Alcohol-based mouthwashes: dry out the oral mucosa, worsening dry mouth and, consequently, bad breath in the medium term
• Fasting and crash diets: promote the production of ketone bodies, which create a characteristic acetone-like breath
• Home remedies (bicarbonate, coconut oil): temporary effect, not supported by solid evidence for reducing volatile sulphur compounds

Bad breath and gums: the connection that gets overlooked

There is a direct, documented link between gum health and halitosis. Inflamed gums bleed: blood is rich in proteins that anaerobic bacteria metabolise into malodorous compounds. Deep periodontal pockets, meanwhile, act as permanent bacterial reservoirs.

Treating periodontitis not only stops bone loss but also significantly reduces chronic bad breath. Many patients who present with active periodontitis find that their bad breath disappears or dramatically decreases after their periodontal treatment cycle, even without any other specific intervention for halitosis.

Article by Dr. Luigi di Bari, Dental Studio in Manfredonia (FG). Last updated: June 2026.