Halitosis was coined using the Latin word for breath, halitus, and the Greek osis, meaning pathological process. This term is meant to describe an unpleasant odor from the mouth, often referred to by patients as “bad breath.”¹

Halitosis can be a serious concern for patients as it can affect their social lives and even contribute to stigmatization and social isolation.^1,2 Studies show personal discomfort and social embarrassment are the main concerns for those affected by halitosis.²

1. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

2. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

Clinically, halitosis can be classified as:^1,2

• Genuine: Obvious oral malodor beyond a socially acceptable level
  • Physiological: Origin is mainly the dorsoposterior region of the tongue without any specific disease or pathological condition (i.e., morning breath)
  • Pathological: Intraoral or extraoral (systemic) pathological origin
• Pseudohalitosis: Patient-perceived halitosis but not perceived by others
• Halitophobia: Fear of halitosis perceived by others

1. Madhushankari, G.S., Yamunadevi, A., Selvamani, M., et al. Halitosis - An Overview: Part-1 - Classification, Etiology, and Pathophysiology of Halitosis. J Pharm Bioallied Sci. 2015; 7(Suppl 2): S339-S343. https://pmc.ncbi.nlm.nih.gov/articles/PMC4606616/

2. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

Morning breath is an example of physiological halitosis. It occurs due to the putrefaction of entrapped food particles and desquamated epithelial cells by bacteria. Additionally, dietary choices such as garlic and onions, which have a high sulfur concentration, can play a role in physiological halitosis. Consequently, upon degradation, they contribute to physiological halitosis that can last hours after consumption.¹

The crypts of the tonsils create a perfect entrapment for food debris. When the food debris that collects in tonsillar crypts becomes calcified, it creates tonsilloliths or tonsil stones, which are a source of malodor.²

The most common factor in physiological halitosis is tongue coating. The dorsum of the tongue provides a reservoir for anaerobic bacteria. These microbes, for example, Veillonella and Actinomyces, are proficient at producing odiferous substances such as volatile sulfur compounds. The association between tongue coating and malodor is strong in the posterior region, near the circumvallate papillae. This area generally has the highest load of gram-negative bacteria, likely due to the inability to properly clean that area of the tongue.^1,3 

1. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

2. Bad Breath (Halitosis). (2022, July 18). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17771-bad-breath-halitosis  

3. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

Pathological halitosis can be caused by both intraoral and extraoral pathology. Intraoral causes account for up to 85% of all halitosis cases. Intraoral causes include periodontal disease, ulcerations, oral malignancy, and craniofacial anomalies.^1,2

Extraoral causes include systemic conditions such as respiratory infections, H. pylori, GI diseases, hepatic failure, and renal failure. Additionally, some medications can contribute to halitosis, including acetaminophen, antihistamines, bisphosphonates, and some chemotherapeutic agents.^1,3

1. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

2. Madhushankari, G.S., Yamunadevi, A., Selvamani, M., et al. Halitosis - An Overview: Part-1 - Classification, Etiology, and Pathophysiology of Halitosis. J Pharm Bioallied Sci. 2015; 7(Suppl 2): S339-S343. https://pmc.ncbi.nlm.nih.gov/articles/PMC4606616/

3. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

Xerostomia can contribute to halitosis. The lack of salivary flow reduces the antimicrobial activity in saliva, which facilitates the transition from gram-positive bacteria to gram-negative species. An increased gram-negative bacterial load increases the production of volatile sulfur compounds, which contributes to oral malodor.^1,2

Salivary factors can also influence the development of malodor. The mechanism is an increase in salivary pH by the intake of amino acids and a decrease in salivary oxygen levels. This decrease stimulates the metabolism of gram-negative bacteria, which are responsible for higher volatile sulfur compounds leading to halitosis.^2,3

1. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

2. Bollen, C.M., Beikler, T. Halitosis: The Multidisciplinary Approach. Int J Oral Sci. 2012; 4(2): 55-63. https://pmc.ncbi.nlm.nih.gov/articles/PMC3412664/

3. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

Microscopic investigation shows a high bacterial species diversity on the dorsum of the tongue. This indicates that oral malodor is likely created by interactions between several bacterial species rather than a few dominant species.^1,2 

Some bacteria associated with halitosis include:¹

• Oral cavity: gram-negative and anaerobic bacteria
• Nasal mucosa: K. ozaenae
• Pharynx and sinuses: Streptococcus species
• Respiratory system: P. aeruginosa
• Stomach: H. pylori
• GI tract: E. faecalis

1. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

2. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725

Chlorhexidine is the most effective antibacterial agent in inhibiting volatile sulfur compounds. However, there are side effects that should be considered, such as staining of the teeth and taste alterations.1 Other antibacterial agents that are effective in reducing halitosis include zinc, triclosan, cetylpridinium chloride, and essential oils.^1,2

Mechanical debridement of the tongue using a toothbrush or tongue scraper is an effective method as well. However, tongue scrapers are thought to be more effective at removing debris from the dorsum of the tongue than toothbrush bristles. Unfortunately, cleaning the dorsum of the tongue only provides relief from halitosis for a short period of time, up to about 30 minutes.^1,2

The etiology of the halitosis must be identified to properly manage it. Individualized therapeutic treatment plans are the best way to manage halitosis since no generalized treatment is successful for all.²

1. Tungare, S., Zafar, N., Paranjpe, A.G. (2023, August 14). Halitosis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK534859/

2. Wu, J., Cannon, R.D., Ji, P., et al. Halitosis: Prevalence, Risk Factors, Sources, Measurement and Treatment - A Review of the Literature. Australian Dental Journal. 2020; 65(1): 4-11. https://onlinelibrary.wiley.com/doi/10.1111/adj.12725