Abstract. Halitosis is a common complaint with substantial psychosocial impact. A systematic review and meta-regression estimated a pooled prevalence of 31.8% (95% CI 24.6–39.0%), with marked heterogeneity between studies. Clinical series and international consensus indicate that the large majority of genuine cases are intra-oral in origin, chiefly tongue coating and gingival or periodontal inflammation, with extra-oral (ENT, blood-borne) causes uncommon. Self-perception correlates poorly with objective assessment, and a meaningful minority of patients presenting with a breath complaint have pseudo-halitosis or halitophobia. Management centres on identifying the source and reducing the volatile sulfur compound (VSC)–producing microbial load through tongue cleaning, oral hygiene and periodontal therapy; however, a Cochrane review of 44 trials rated the evidence for specific interventions as low to very low certainty. This review summarises current evidence for the general dental practitioner. A plain-language companion for patients is available: Do I Have Bad Breath? How to Tell, and What Actually Fixes It.
Epidemiology
Silva and colleagues pooled 13 studies meeting inclusion criteria and reported a combined prevalence of 31.8%. Year of publication and the socioeconomic status of the study country appeared to influence estimates, and the authors noted a possible upward trend over time. Heterogeneity in definitions and measurement (self-report, organoleptic scoring, instrumental VSC measurement) limits direct comparison, and the true population burden should be regarded as uncertain within a broad range.
Etiology
Intra-oral halitosis. In a series of 2,000 consecutive patients at a multidisciplinary breath clinic in Leuven, Quirynen et al. identified an oral cause in 76%: tongue coating alone (43%), gingivitis or periodontitis (11%), or both (18%). The Seemann consensus workshop concluded that approximately 90% of cases arise within the oral cavity. Malodour results predominantly from proteolytic, Gram-negative anaerobic metabolism on the tongue dorsum and in periodontal pockets, generating hydrogen sulfide and methyl mercaptan. A systematic review and meta-regression by Silva et al. supports an association between periodontitis and halitosis, though heterogeneity of exposure and outcome definitions complicates quantification. Contributory factors include reduced salivary flow, deep carious lesions, food impaction around defective restorations, and poorly cleaned removable prostheses.
Extra-oral halitosis. In the Leuven series, ENT or other extra-oral causes accounted for 4%. Tangerman and Winkel describe the majority of extra-oral cases as blood-borne, frequently attributable to dimethyl sulfide, which is not removed by oral hygiene and may reflect hepatic, renal or metabolic conditions. A 2023 systematic review by Memon et al. similarly found that, despite a multifactorial aetiology, intra-oral factors account for most cases. Gastro-oesophageal sources are frequently assumed by patients but are a minority contributor.
Pseudo-halitosis and halitophobia. In the same series, 16% of patients had no objectively detectable malodour. These patients warrant reassurance, careful explanation and, where concern persists despite objective normality, consideration of psychological support.
Diagnosis
Assessment should combine history (duration, timing, diurnal pattern, third-party report, medications, systemic history) with clinical examination of tongue coating, periodontal status, caries, restorations, prostheses and salivary flow. Organoleptic assessment remains the reference method in practice and can be supplemented by portable sulfide monitors or gas chromatography where available. Self-assessment is unreliable: Romano et al. found limited correspondence between patients’ self-assessment and organoleptic scores, reflecting olfactory adaptation to one’s own odour. A third-party report from a trusted person is a useful adjunct. Patients without an identifiable oral source, or with malodour persisting after oral causes are treated, should be referred for medical or ENT evaluation, as recommended by the consensus workshop.
Management
- Tongue cleaning. An earlier Cochrane review (two trials, 40 participants) found a small but statistically significant VSC reduction with scrapers or cleaners versus toothbrushes, with effects that appeared short-lived. That review has since been subsumed into the broader 2019 Cochrane review.
- Periodontal therapy and oral hygiene. Treatment of gingivitis and periodontitis, interdental cleaning, and correction of plaque-retentive restorations address the principal reservoirs.
- Topical agents. Kumbargere Nagraj et al. (Cochrane, 2019; 44 trials) categorised interventions as mechanical debridement, chewing gums, systemic deodorising agents, topical agents, toothpastes, mouthrinses, tablets and combinations. They found low- to very-low-certainty evidence of benefit versus placebo or control and could not establish superiority of any intervention or concentration. Rinses containing zinc or chlorhexidine may be used adjunctively, with that uncertainty explained to patients.
- Probiotics. Tay et al. (2022) could not confirm a beneficial effect of probiotics in periodontally treated patients or as an adjunct to non-surgical periodontal therapy. This is a reasonable null finding to share with patients who ask about over-the-counter products.
- Salivary support. Address xerostomia and review medications; see our review of xerostomia and salivary gland hypofunction.
- Referral. Refer when no oral source is found or malodour persists after treatment; manage halitophobia with reassurance and, where appropriate, psychological referral.
Clinical Implications
Because most halitosis is intra-oral, the general dental practitioner is well placed to diagnose and manage it. The strongest practical levers — tongue cleaning, periodontal therapy and plaque control — are low-cost and low-risk, even though the trial evidence for individual products is weak. Clinicians should avoid overstating the efficacy of commercial rinses or probiotics, and should recognise and sensitively manage pseudo-halitosis. Related reviews: tobacco, e-cigarettes and periodontal health and GERD and dental erosion.
References
- Silva MF, et al. Estimated prevalence of halitosis: a systematic review and meta-regression analysis. Clinical Oral Investigations. 2018;22:47–55.
- Quirynen M, Dadamio J, Van den Velde S, et al. Characteristics of 2000 patients who visited a halitosis clinic. Journal of Clinical Periodontology. 2009;36(11):970–975.
- Seemann R, Da Conceicao MD, Filippi A, et al. Halitosis management by the general dental practitioner — results of an international consensus workshop. Journal of Breath Research. 2014;8(1):017101.
- Silva MF, Cademartori MG, Leite FRM, López R, Demarco FF, Nascimento GG. Is periodontitis associated with halitosis? A systematic review and meta-regression analysis. Journal of Clinical Periodontology. 2017;44(10):1003–1009.
- Tangerman A, Winkel EG. Extra-oral halitosis: an overview. Journal of Breath Research. 2010;4(1):017003.
- Memon et al. Aetiology and associations of halitosis: a systematic review. Oral Diseases. 2023.
- Romano F, et al. Patients’ self-assessment of oral malodour and its relationship with organoleptic scores and oral conditions. International Journal of Dental Hygiene. 2010.
- Outhouse TL, Al-Alawi R, Fedorowicz Z, Keenan JV. Tongue scraping for treating halitosis. Cochrane Database of Systematic Reviews. 2006;(2):CD005519.
- Kumbargere Nagraj S, Eachempati P, Uma E, et al. Interventions for managing halitosis. Cochrane Database of Systematic Reviews. 2019;(12):CD012213.
- Tay JRH, Ng E, Lai CWM, Lim LP, Ong MMA. The efficacy of probiotics in the management of intra-oral halitosis: a systematic review. Clinical Oral Investigations. 2022;26(7):4687–4700.
This review is intended for educational purposes and does not replace individual clinical judgment or personalized medical or dental advice. Reviewed by Dr. Nardys Fridman, DDS, Fridman Family Dental Care, Valencia, CA.
