What are the causes of halitosis (bad breath)?

Causes of Halitosis (Bad Breath)

Halitosis is primarily caused by oral conditions (85-90% of cases), with the most common being tongue coating, poor oral hygiene, and periodontal disease. 1, 2

Oral Causes (85-90% of cases)

Primary Oral Causes

• Tongue coating: Bacterial accumulation on the posterior third of the dorsal surface of the tongue is the most common cause 3, 4
• Poor oral hygiene: Inadequate plaque control leading to bacterial overgrowth 1
• Periodontal disease: Gingival inflammation and periodontal pockets harbor odor-producing bacteria 5
• Food impaction: Trapped food particles between teeth that decompose 2

Secondary Oral Causes

• Dental problems:
  • Deep carious lesions 1
  • Faulty dental restorations 2
  • Ill-fitting or unclean dentures 5
• Oral infections:
  • Pericoronitis (infection around partially erupted teeth) 1
  • Peri-implant disease 1
  • Mucosal ulcerations 1
• Oral carcinomas 2
• Throat infections 2
• Dry mouth (xerostomia) due to:
  • Medication side effects (anticholinergics, antidepressants, antihistamines, etc.) 6
  • Salivary gland dysfunction 6
  • Dehydration 6

Non-Oral Causes (10-15% of cases)

Upper Respiratory Tract

• Rhinosinusitis: Bacterial sinusitis can cause halitosis due to postnasal drainage 7
• Allergic and non-allergic rhinitis: Postnasal drainage can lead to halitosis 7
• Tonsil infections: Cryptic tonsils can trap debris and cause odor 4

Lower Respiratory Tract

• Bronchitis and pneumonia 4
• Bronchiectasis 4

Systemic Conditions

• Metabolic disorders:
  • Diabetes mellitus (ketoacidosis) 4
  • Renal failure 2
  • Hepatic failure 2
• Gastrointestinal disorders:
  • Gastroesophageal reflux disease (GERD) 7
  • Helicobacter pylori infection 4
• Rare metabolic disorders:
  • Trimethylaminuria (fish odor syndrome) 2, 4

Other Contributing Factors

• Dietary factors:
  • Certain foods (garlic, onions, spicy foods) 1
  • Alcohol consumption 6
• Tobacco use: Smoking or chewing tobacco 1
• Medications that reduce salivary flow 6
• Fasting and low-carbohydrate diets: Can lead to ketosis and distinctive breath odor 4

Diagnostic Approach

1. Clinical evaluation:

   • Assess oral hygiene status
   • Examine for periodontal disease
   • Inspect tongue coating
   • Check for dental caries, faulty restorations, and ill-fitting prostheses

2. Differentiate oral vs. non-oral sources:

   • If halitosis persists despite good oral hygiene and treatment of oral conditions, consider non-oral causes
   • Evaluate for symptoms of sinusitis, rhinitis, or respiratory conditions 7
   • Consider systemic conditions if other symptoms are present

3. Assessment methods:

   • Organoleptic assessment (direct smelling by clinician)
   • Sulfide monitoring devices
   • Gas chromatography (in specialized settings) 4

Management Algorithm

1. For oral causes:

   • Improve oral hygiene: Regular brushing, flossing, and professional dental cleaning
   • Tongue cleaning: Daily cleaning of the dorsal surface of the tongue, particularly the posterior third 3
   • Treat periodontal disease: Scaling and root planing as needed 5
   • Address dental issues: Repair faulty restorations, treat caries, clean dentures properly 2
   • Manage xerostomia: Increase fluid intake, use saliva substitutes, review medications 6

2. For non-oral causes:

   • Treat rhinosinusitis: Appropriate antibiotics for bacterial sinusitis 7
   • Manage allergic rhinitis: Antihistamines, nasal steroids 7
   • Address systemic conditions: Refer to appropriate specialists for management of underlying diseases

3. Adjunctive measures:

   • Antimicrobial mouth rinses: Chlorhexidine, cetylpyridinium chloride, or essential oils to reduce bacterial load 5
   • Zinc-containing products: Help neutralize volatile sulfur compounds 4

Remember that halitosis can significantly impact a person's quality of life and social interactions. Proper diagnosis and targeted treatment based on the underlying cause are essential for effective management.