Red flags
Older patients





Halitosis (oral malodour, bad breath, fetor oris) is defined as offensive breath odour, with the potential to cause personal discomfort and social embarrassment. 1 The condition is common to all age groups, with an estimated global prevalence of between 15% and 50% in adult populations.2-5 Halitosis has a range of local oral and systemic causes - and can indicate an underlying disease. However, most sources of malodour are intra-oral (85%), including poor dental hygiene.



A full history should be elicited, including duration and severity of halitosis (plus whether other people have noticed or complained), the adequacy of the patient’s oral hygiene, and the relationship of halitosis to ingestion of causative foods. A weekly diet sheet can be helpful; listing all consumed foods, drinks and snacks, and detailing the presence/severity of halitosis.

A review of systems should inquire as to symptoms of causative disorders, such as nasal discharge, face or head pain (sinusitis, nasal foreign body), productive cough and fevers (pulmonary infection), regurgitation of undigested food and reflux. Predisposing factors such as dry mouth, dry eyes, or both (Sjögren syndrome) should be noted.6,7

Past medical history should ask about the use of alcohol and tobacco. Drug history should specifically inquire about medications, including over the counter preparations and herbal remedies that can cause dry mouth. There are over 1,800 drugs that list dry mouth as a side effect, ones that are classically attributable include atropine, antidepressants (tricyclics and SSRIs), anti-histamines and proton pump inhibitors.


A thorough physical examination is necessary; including vital signs for the presence of fever. The nose is examined for discharge, signs of infection or foreign body, and the mouth for signs of caries, food debris, periodontal disease, dental infection, and cancer. Signs of oral dryness include whether the mucosa is dry, sticky, or moist (revealing a dry or moist mouth due to the amount of saliva) and whether saliva is foamy, stringy, or normal in appearance (looking at whether a dry mouth is due to the quality of saliva). For example, classically reduced amounts of saliva will collect in small frothy pockets in an otherwise dry mouth. The throat is examined for signs of infection and cancer.6,7

Red flags

A number of findings in the history and examination should be of particular concern and include fever, purulent nasal discharge or sputum, ulcerating nasal lesions, visible or palpable oral lesions, and unexplainable neck masses.

Older patients

Older patients are more likely to be taking polypharmacy, including drugs that cause dry mouth. There may be limited age-related restrictions in manual dexterity, or musculoskeletal or neurological conditions that limit the ability to clean teeth adequately – all contributing to halitosis. One should also be mindful that oral cancers are more common in older people and may underlie malodour symptoms.


Assessment of halitosis is usually subjective by smelling exhaled air coming from the mouth and nose, and comparing the two - the organoleptic (‘sniff test’) method. Ideally, for 48 hours prior the patient avoids eating typically causative foods, and for two hours prior to abstains from eating, chewing, drinking, gargling, rinsing, or smoking. During the test, the patient exhales 10 centimetres away from the examiner’s nose, first through the mouth and then with the mouth closed.

Odour originating in the mouth, but not detectable from the nose,  is likely to be either oral or pharyngeal in origin. Odour originating in the nose may come from the sinuses or nasal passages. In rare cases where similar odour equally comes from both the nose and mouth, then one of the systemic causes be inferred. In general, oral causes of halitosis result in a putrefying, pungent smell, whereas systemic conditions result in a more subtle, abnormal odour. If the site of origin is unclear, the posterior tongue is scraped with a plastic spoon. After five seconds, the spoon is sniffed five centimetres from the examiner’s nose; malodour suggests culpable bacteria on the tongue.8,9,10  

Specialist centres (typically tertiary university hospitals with oral medicine departments, such as the Dental Institute at Guys’ Hospital, London) may have a halimeter for objectively measuring responsible volatile sulphur compounds (methyl mercaptan, hydrogen sulphide, dimethyl sulphide).  Microbiological investigations include the BANA (benzoyl-arginine-naphthyl-amide) test and darkfield microscopy can also be helpful. The BANA test detects the presence of three periodontal microorganisms found in subgingival plaque (Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia) which share the unique ability of hydrolysing the trypsin substrate; benzoyl-arginine-naphthyl-amide. Brightfield microscopy uses staining of the specimen with background illumination, darkfield microscopy does not require the use of stain, which may kill the organism, and the specimen appears bright against a dark background. Portable sulphur monitors, gas chromatography, and chemical tests of tongue scrapings are available in research settings and oral medicine tertiary centres.10,11,12     


Visible oral pathology may be presumed a cause in patients with no extraoral symptoms or signs. Conditions treatable within primary care should be addressed, with advice to avoid recurrence, while more dentally related conditions should be encouraged towards review with a general dental practitioner. Referral to oral surgery/medicine is indicated if more urgent signs/symptoms are present. In cases of malodour with an extra-oral aetiology, the history and examination should highlight the diagnosis and direct management or referral.

Halitosis related to a certain food or drink with no other clinical findings can undergo a trial of avoidance for at least 48 hours, followed by the sniff test, to clarify the diagnosis.1,13



Oral causes are usually related to microorganisms and management is grouped into (1) mechanical reduction of intra-oral nutrients and micro-organisms; (2) chemical reduction of microorganisms; (3) changing volatile fragrant gasses into non-volatile components or (4) masking the malodour.8,14-16

Mechanical reduction

Mechanical cleaning (scraping) of the dorsum of the tongue reduces microbes, desquamating cells and the available nutrients to the microorganisms, leading to an improvement of symptoms.17-19 Home tongue cleaning to reduce the substrate for putrefaction can be performed with an over the counter scraper applied gently with low force, rather than a regular toothbrush that can cause trauma to the tongue.19-20 Since periodontitis is one of the main causes of oral malodour, professional periodontal therapy should be performed to include removal of plaque both supra- and sub-gingivally with an associated beneficial reduction in the bacterial load.

Chemical reduction

Chlorhexidine (a disinfectant and antiseptic, active against Gram-positive and Gram-negative organisms) is the most efficient molecule against plaque, and rinsing with 0.2% solution has been shown to causes a reduction of 43% in VSCs and 50% in the organoleptic scores throughout a day.21 Essential oils provide only a short-term and restricted effect with a negligible effect in reduction of odour-producing bacteria.22,23 Chlordioxide/chlorine dioxide (an antimicrobial agent with virucidal and bactericidal that can penetrate the polysaccharide biofilm covering oral surfaces, act on the bacteria within and destroy the film) can reduce oral malodour through the oxidation of hydrogen sulphide, methyl mercaptan; with a reduction of 29% in odour after four hours.24,25 Hydrogen sulphide gas has characteristic rotten egg odour, often produced from the microbial breakdown of organic matter. Methyl mercaptan (methanethiol) is an organosulphur gas with a similarly putrid odour that can be degraded into hydrogen sulphide. Equally, cysteine and methionine are sulphur containing amino acids with unpleasant odours. Triclosan (an antibacterial and antifungal agent) is effective against the majority of oral bacteria, with an 84% reduction of VSCs after three hours.22 

Toothpaste containing stannous fluoride, zinc or triclosan have demonstrated an effect in reducing oral malodour, but for a limited period of time.21,26-30 Essentially preparations with oxidant formulations (typically containing hydrogen peroxide or chlorine dioxide) help abolish odours for a longer period.30-31

Transformation of volatile sulphur components

Metal ions with an affinity for sulphur, pick up sulphur-containing gasses. Zinc, mercury and copper are the most important metals in this regard.32-34 A commercial rinse (containing 0.005% chlorhexidine, 0.05% cetylpyridinium chloride and 0.14% zinc lactate) is significantly more efficient than chlorhexidine alone, due to the effect of zinc, and will transform the VSCs into less odorous gases. 33-35


Rinsing products, sprays, mint tablets or chewing gum only have a short-term masking effect as their predominant effect.36-39 Their main action is the beneficial increase in saliva production, thereby more soluble sulphur components will be retained for a short period of time, compared with less soluble, and non-soluble sulphur components.39 Chewing sugar-free gum may also help to remove food debris from around the teeth.

Oral hygiene

The improvements in oral hygiene necessary to overcome halitosis due to poor habits include flossing, twice daily toothbrushing with fluoride toothpaste, and scraping of the tongue.

A patient should be advised to:

  • Aim to clean teeth twice a day, morning and night, using a fluoride toothpaste.
  • Brush gums and tongue.
  • Floss, or use inter-dental brushes between teeth to remove particles of food.
  • Drink plenty of water.
  • Visit the dentist regularly for review.

A small-headed toothbrush with medium texture bristles should be recommended. There is evidence that powered toothbrushes can be more effective than manual toothbrushes, however, any toothbrushing is better than none. Teeth should be brushed for at least two minutes, with all tooth surfaces cleaned. A general dental practitioner is ideally placed to modify and improve the tooth-brushing technique. Disclosing tablets are helpful, particularly in children, in helping identify tooth surfaces that are not being cleaned adequately.16 The tablets contain a dye such that after being chewed, spat out and rinsed - the dental plaque on teeth is stained brightly and made clearly visible.

Cleaning between the teeth should be carried out at least once a day. Dental floss or tape should be used to clean small interdental spaces, while wider interdental spaces benefit from the use of interdental brushes. Guidance on which type and size of the interdental brush to use can be provided at a dental review.16


Halitosis in association with the dietary intake is usually obvious once the food/drink has been identified and avoidance of the offending substance is the logical and best prevention. Culpable causes, including crash diets, should be stopped with a cessation of halitosis to be expected on resuming a normal diet. Advise to reduce-to-quit smoking is appropriate, as is guidance on the consumption of alcohol.


Individuals who fail to drink the recommended volume of water/fluids (at least six to eight glasses daily) and therefore tend towards the dry mouth, with the associated increased risk of halitosis, may be inclined (together with smokers and sufferers of transient halitosis) to rely on chewing gum for mouth moistness. Providing advice on avoiding dehydration is likely to have benefits in addition to the control of halitosis.

Dry mouth

Dry mouth symptoms can be treated with sialagogues (drugs that promote secretion, and therefore flow rate of saliva by stimulating functioning salivary gland tissue to produce more saliva), or artificial saliva substitutes. In patients with Sjögren's syndrome and those who have undergone radiation therapy, pilocarpine can be used with evidence-based results.40


Aside from referral to secondary care when necessary, a number of conditions can be treated in primary care. Acute pharyngitis can be treated symptomatically, with aspirin effective when started from the prodromal stage, particularly in dispensible form when gargled before swallowing. Care must be taken to avoid aspirin in children under 16, due to the risk of Reye’s syndrome, in which case dispersible paracetamol may be used, albeit with a reduced evidence base. Chlorhexidine sprays can prevent bacterial overgrowth and reduce the malodour.41 Foreign objects in the nose should be removed. Reflux associated halitosis should be managed with the typical advice of weight reduction, limiting coffee and tobacco, avoiding large meals in the evening, placing the head of the bed in a slightly elevated position, and use of proton pump inhibitor drugs, initially for one month followed by a review.


Psychogenic halitosis, including pseudo-halitosis and halitophobia, may require psychiatric consultation. However, management is a challenge since patients will often have intransigent beliefs, no matter what a clinician discusses. It is not uncommon for such patients to seek different GPs, and different surgeries, to find an argument for their self-esteemed problem. Many of the cases with imagined halitosis described in the literature resemble the psychiatric syndrome of social phobia.42-43

Selective Serotonin Reuptake Inhibitors and tricyclic antidepressants can help,44 however, caution should be used since xerostomia is a side effect of both medications - risking an increase of halitosis awareness.45


Halitosis is a common condition, largely due to intra-oral sources, with a limited number of cases secondary to extra-oral conditions. The commonest intra-oral cause is the presence of anaerobic microorganisms in the tongue coating, followed by poor oral hygiene – once addressed through oral hygiene measures, the halitosis often significantly improves. Malodour due to gingivitis or periodontitis should receive the input of dental professionals. Halitosis can be a presenting factor for systemic disease and, in the absence of obvious intra-oral origin, a wider investigation is warranted. Halitosis is only rarely due to more serious disease. Imagined halitosis can indicate underlying psychological problems. A reasonable number of halitosis patients, with intra- or extra-oral causes can be treated in primary care, if this is not possible or practical then either review with a dental practitioner or referral to secondary care is indicated.

Dr Matthew West, Dr Iram Sofia Tawhid
GP, Herts Valley CCG 


Part one of this article looked at the underlying causes and can be read here.



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