Halitosis is a frequent or persistent unpleasant breath odor.
(See also Evaluation of the Dental Patient.)
Pathophysiology of Halitosis
Halitosis most often results from degradation of food particles by anaerobic gram-negative bacteria in the mouth, producing volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan (1). Causative bacteria may be present in areas of periodontal disease, particularly when ulceration or necrosis is present. The causative organisms reside deep in periodontal pockets around teeth. In patients with healthy periodontal tissue, these bacteria may proliferate on the dorsal posterior tongue.
Factors contributing to the overgrowth of causative bacteria include decreased salivary flow (eg, due to parotid disease, Sjögren syndrome, or use of anticholinergic medications), salivary stagnation, and increased salivary pH.
Certain foods or spices, after digestion, release the odor of that substance to the lungs; the exhaled odor may be unpleasant to others. For example, the odor of garlic is noted on the breath by others 2 or 3 hours after consumption, long after it is gone from the mouth.Certain foods or spices, after digestion, release the odor of that substance to the lungs; the exhaled odor may be unpleasant to others. For example, the odor of garlic is noted on the breath by others 2 or 3 hours after consumption, long after it is gone from the mouth.
Pathophysiology reference
1. van den Broek AM, Feenstra L, de Baat C. A review of the current literature on aetiology and measurement methods of halitosis. J Dent. 2007;35(8):627-635. doi:10.1016/j.jdent.2007.04.009
Etiology of Halitosis
Most cases result from intraoral conditions, such as the accumulation of food and bacteria on the tongue, interdental plaque accumulation, gingivitis, and periodontitis (1). A variety of systemic and extraoral conditions account for the remainder (see table ).
The most common causes overall are the following:
Smoking
Ingested foods that have a volatile component
Gingival disorders (eg, gingivitis) and periodontal disorders (eg, periodontitis) produce sulfur compounds, which are released when bacteria in the oral cavity degrade sulfur-containing amino acids (2).
Smoking may alter the oral microbiome, which may contribute to the production of volatile sulfur compounds (3).
Gastrointestinal disorders rarely cause halitosis, because the esophagus is normally collapsed. However, certain disorders (eg, gastroesophageal reflux disease [GERD], esophageal diverticula, stomach cancer) may cause halitosis. It is a misconception that breath odor reflects a state of digestion and bowel function.
Other breath odors
Several systemic diseases produce volatile substances detectable on the breath, although not the particularly foul, pungent odors typically considered halitosis. Diabetic ketoacidosis (DKA) produces a sweet or fruity odor of acetone, liver failure produces a unique mousy odor (musty, sweet, and/or sulfurous), and renal failure produces an odor of urine or ammonia.
Some Causes of Halitosis
Cause | Suggestive Findings | Diagnostic Approach |
|---|---|---|
Oral conditions | ||
Bacteria on dorsum of tongue | Malodorous tongue scrapings, healthy oral tissue | Oral examination |
Gingival or periodontal disease | Oral disease, often including bleeding and/or purulent exudate Apparent during the examination Often history of poor oral hygiene | Oral examination Dental consultation |
Necrotic oral cancer (rare—usually identified before becoming necrotic) | Lesion usually identifiable during the examination In older patients, who often have extensive history of using alcohol, tobacco, or both | Biopsy, CT, or MRI |
Extraoral disorders | ||
Nasal foreign body* | Usually in children Purulent or bloody nasal discharge Visible on examination | History and physical examination Sometimes imaging |
Necrotic nasopharyngeal cancer* | Discomfort with swallowing | History and physical examination |
Necrotic pulmonary infection (eg, lung abscess, bronchiectasis, foreign body) | Productive cough Fevers | Chest radiograph Sputum cultures Sometimes CT or bronchoscopy |
Psychogenic halitosis | Malodor not detected by others Often history of other functional complaints | History and physical examination |
Sinus infection* | Purulent nasal discharge Facial pain, headache, or both | History and physical examination Sometimes CT |
Undigested food regurgitated when lying down or bending over | Video barium swallow or upper gastrointestinal endoscopy | |
Ingested substances† | ||
Alcoholic beverages, garlic, onions, tobaccoAlcoholic beverages, garlic, onions, tobacco | Use apparent on history | History and physical examination Trial of avoidance |
* Malodor is typically more prominent from the nose than the mouth. | ||
† Typically, a diagnosis of exclusion after examination rules out other causes. | ||
Etiology references
1. van den Broek AM, Feenstra L, de Baat C. A review of the current literature on aetiology and measurement methods of halitosis. J Dent. 2007;35(8):627-635. doi:10.1016/j.jdent.2007.04.009
2. Lee YH, Shin SI, Hong JY. Investigation of volatile sulfur compound level and halitosis in patients with gingivitis and periodontitis. Sci Rep. 2023;13(1):13175. Published 2023 Aug 14. doi:10.1038/s41598-023-40391-3
3. Wu J, Peters BA, Dominianni C, et al. Cigarette smoking and the oral microbiome in a large study of American adults. ISME J. 2016;10(10):2435-2446. doi:10.1038/ismej.2016.37
Evaluation of Halitosis
History
History of present illness should ascertain duration and severity of halitosis (including whether other people have noticed or complained), assessment of the patient’s oral hygiene, and the relationship of halitosis to ingestion of causative foods (see table ).
Review of systems should seek symptoms of causative disorders, including nasal discharge and face or head pain (sinusitis, nasal foreign body), productive cough and fevers (pulmonary infection), and regurgitation of undigested food when lying down or bending over (Zenker diverticulum). Predisposing factors such as dry mouth, dry eyes, or both (Sjögren syndrome) should be noted.
Past medical history should ask about duration and amount of use of alcohol and tobacco. Medication history should specifically ask about use of medications that can cause dry mouth (eg, those with anticholinergic effects—see table ).
Physical examination
Vital signs are reviewed, particularly for presence of fever.
The nose is examined for discharge and foreign body.
The mouth is examined for signs of periodontal disease, dental infection, and cancer. Signs of apparent dryness are noted (eg, whether the mucosa is dry, sticky, or moist, and whether saliva is foamy, stringy, or normal in appearance).
The pharynx is examined for signs of infection and cancer.
Organoleptic Testing
Organoleptic evaluation of exhaled air is conducted. In general, oral causes of halitosis result in a putrefying, pungent smell, whereas systemic conditions result in a more subtle, abnormal odor. Ideally, the patient avoids consuming pungent or malodorous foods for a period before testing (eg, 48 hours); the patient also abstains from eating, chewing, drinking, gargling or rinsing with, or smoking anything immediately before testing. During the test, the patient exhales approximately 10 cm away from the examiner’s nose, first through the mouth and then with the mouth closed (1). Malodor that is perceived as worse through the mouth suggests an oral etiology; malodor that is perceived as worse through the nose suggests a nasal or sinus etiology. Similar malodor through both nose and mouth may suggest a systemic or pulmonary cause. The examiner rates the intensity of the breath odor using a standardized scoring scale, which ranges from no detectable odor to an extremely foul odor.
If site of origin is unclear, the posterior tongue is scraped with a plastic spoon. The spoon is then sniffed approximately 5 cm from the examiner’s nose; a bad odor suggests the malodor is caused by bacteria on the tongue.
Red flags
The following findings are of particular concern:
Fever
Purulent nasal discharge or sputum
Visible or palpable oral lesions
Interpretation of findings
Because oral causes (eg, periodontitis) are by far the most common (2), any visible oral disease may be presumed to be the cause of halitosis in patients with no extraoral symptoms or signs, and a dentist should be consulted. When other disorders may be involved, clinical findings often suggest a diagnosis (see table ).
In patients whose symptoms seem to be related to intake of certain food or drink and who have no other findings, a trial of avoidance (followed by a sniff test) may clarify the diagnosis.
Testing
Extensive diagnostic evaluation is typically not necessary, except when the history and physical examination suggest an underlying disease (see table ). Portable sulfur monitors, gas chromatography, and chemical tests of tongue scrapings are not widely available in routine clinical practice, and their use is largely limited to research settings and specialized centers that focus on halitosis evaluation and treatment.
Evaluation references
1. Murata T, Yamaga T, Iida T, Miyazaki H, Yaegaki K. Classification and examination of halitosis. Int Dent J. 2002;52 Suppl 3:181-186. doi:10.1002/j.1875-595x.2002.tb00921.x
2. Memon MA, Memon HA, Muhammad FE, et al. Aetiology and associations of halitosis: A systematic review. Oral Dis. 2023;29(4):1432-1438. doi:10.1111/odi.14172
Treatment of Halitosis
Regular oral hygiene and dental care
Cause treated
Underlying diseases are treated.
If the cause is oral, the patient should see a dentist for professional cleaning and treatment of gingival disease and caries. Home treatment involves enhanced oral hygiene, including thorough flossing, toothbrushing, and brushing of the tongue with the toothbrush or a scraper. Mouthwashes containing antimicrobial agents or zinc ingredients are generally recommended as adjunctive treatment in combination with dental hygiene, but they are of limited benefit (1). Mouth rinses containing chlorhexidine or cetylpyridinium chloride may play a role in reducing levels of tongue bacteria that contribute to halitosis. Mouth rinses that contain chlorine and zinc may neutralize sulfur compounds that contribute to halitosis. ). Mouth rinses containing chlorhexidine or cetylpyridinium chloride may play a role in reducing levels of tongue bacteria that contribute to halitosis. Mouth rinses that contain chlorine and zinc may neutralize sulfur compounds that contribute to halitosis.
Psychogenic halitosis may require psychiatric consultation.
Treatment reference
1. Kumbargere Nagraj S, Eachempati P, Uma E, Singh VP, Ismail NM, Varghese E. Interventions for managing halitosis. Cochrane Database Syst Rev. 2019;12(12):CD012213. Published 2019 Dec 11. doi:10.1002/14651858.CD012213.pub2
Geriatrics Essentials: Halitosis
Older patients are more likely to take medications that cause dry mouth, which leads to difficulties with oral hygiene (as do limited manual dexterity and conditions such as rheumatoid arthritis and Parkinson disease) and hence to halitosis, but they are otherwise not more likely to have halitosis. Also, oral cancers are more common with aging and are more of a concern among older than younger patients.
Key Points
Most halitosis results from degradation of food particles by anaerobic gram-negative bacteria that reside around the teeth and on the dorsum of the tongue.
Extraoral disorders may cause halitosis and are often accompanied by suggestive findings.
Home treatment includes enhanced toothbrushing, flossing, and tongue brushing or scraping.
Mouthwashes provide only brief benefit.
