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Oral malodour (halitosis) is common; everyone has transient episodes of halitosis.

By far the most common cause is oral accumulation of food debris and gingival inflammation (gingivitis) due to poor oral

hygiene. All types of gingivitis and periodontitis can give rise to oral malodour, although the most striking halitosis arises with acute necrotising ulcerative gingivitis ('Vincent's disease, 'trench mouth') when there is necrotic ulceration of the gums.

The odours of true orally derived malodour are due to the generation of volatile sulphur compounds (methyl mercaptan, hydrogen sulphide, dimethil sulphide), diamines (eg putrescine and cadaverine) and short chain fatty acids (butyric, valeric and propionic acid) generated by gram-negative anaerobes (such as Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Bacteroides forsythus and Treponella denticola) ­ see box below for other causes.

The posterior tongue is the likely site of bacteria giving rise to bad breath in patients without severe plaque-related gingival and periodontal disease.

What works?

There are few RCTs on the effectiveness of treatments for physiological oral malodour.

The majority of patients with objective oral malodour have oral disease which is likely to be the source. Good self-administered tooth cleaning or involvement of a hygienist are


This may be helpful, either with a tongue scraper (available in most pharmacies), or a tongue scraper attached to electric toothbrushes or simply with a spoon or toothbrush. Surprisingly, there are no RCTs to confirm this as an effective measure.

Two RCTs found mouthwash (one containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate1, the other containing cetylpyridinium chloride2) lessened breath odour at two to four weeks compared with placebo. Mouthwashes such as Dentyl pH, or triclosan-containg mouthwashes (eg Colgate Total) ,can lessen oral malodour.

What doesn't work?

Single-use mouthwash is of little help in reducing oral unpleasantness and odour intensity, or it will provide only short-term benefit3.


Generally the treatment of detectable oral malodour should be cheap, as the cost of the mouthwashes varies with the product, ranging from £2.52 to £7.95 for a 500ml bottle. All can be obtained over-the-counter. The treatment of psychogenically driven symptoms of oral malodour is likely to be very expensive as this involves psychiatric referral.

The bottom line

1 Assessment and treatment are usually easy and not expensive.

2 In general practice, simple smelling of mouth breath is often as useful as more sophisticated methods to judge the quality and severity of malodour.

3 Microbiological investigation of oral or pharyngeal samples is rarely of practical benefit.

4 Good oral hygiene is the most likely means of preventing and lessening oral malodour.

Other halitosis causes

· Mild transient oral malodour often arises following sleep, known as 'morning


· Volatile foodstuffs such as garlic, onions and some spices

· Upper respiratory tract infections, as a consequence of nasal/sinus secretions passing

into the pharynx and/or the patient mouth breathing

· Foreign objects within the nose (eg in children), tonsillitis and tonsoliths can give rise to striking oral malodour

· There are small numbers of patients with trimethylaminuria ('fish odour syndrome' in which there is excess trimethylamine due to defective flavin monooxigenase (FMO)) which can give rise to a long-term oral and body odour; indeed there are reports of such odour becoming more intense with onset of menstruation

· A small group of individuals have delusional thoughts that they have oral malodour, yet have no objective evidence of halitosis

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