Halitosis · What Is It, Causes, Symptoms, and More

The cause of halitosis depends on the specific subtype. Physiologic halitosis is the most common type and is generally due to anaerobic bacteria that are part of the normal oral flora. The primary culprits are gram-negative anaerobes (e.g., Bacteroides forsythus, Porphyromonas gingivalis, Prevotella intermedia) that produce malodorous substances, including volatile sulfur compounds (e.g., hydrogen sulfide, methyl mercaptan, and dimethyl sulfide). Physiologic halitosis is worse in the morning due to low saliva flow, as saliva plays a role in cleaning the oral cavity and has antibacterial properties. Therefore, halitosis can be exacerbated by breathing through the mouth, causing dry mouth. Also implicated in physiologic halitosis are the tongue's crevices and fissures that can trap odor-causing bacteria or food particles. This can be exacerbated by the consumption of aromatic foods (e.g., onions, garlic), certain beverages (e.g., alcohol, coffee), and tobacco smoking.

Pathologic halitosis can be caused by disorders of the oral cavity, such as gingivitis (i.e., gum inflammation) and periodontitis (i.e., gum disease). Defective dental restorations, unclean dentures, and oral abscesses may also be implicated in bad breath. Tonsillar pathology (e.g., tonsillitis, peritonsillar abscess), disorders of the respiratory tract (e.g., bronchiectasis, lung abscess), and structural gastrointestinal tract disorders (e.g., Zenker diverticulum, gastrocolic fistula) may cause pathologic halitosis.

Pseudo-halitosis is a psychological cause of halitosis and may be secondary to monosymptomatic hypochondriacal psychosis and olfactory reference syndrome, two psychiatric conditions where the individual erroneously believes they emit excess odor. Some individuals who have been treated for objective bad breath may develop psychological halitosis even after the bad breath is under control.

Treatment of physiologic halitosis primarily focuses on oral hygiene, and it usually resolves immediately after brushing, flossing, eating, and drinking plenty of water. Brushing or scraping the tongue using gentle tongue scrapers and using antiseptic agents, such as toothpaste and mouthwash, before bedtime can help further reduce the bacterial load and reduce mouth odor. Behavioral modifications can help get rid of bad breath including maintaining good hydration, chewing sugar-free gum to stimulate salivary glands, decreasing alcohol, garlic, and onion intake, and stopping smoking. 

Treatment of pathologic halitosis includes addressing any underlying causes. For example, treatment involves debriding plaque in periodontitis; drainage and antimicrobial therapy for peritonsillar abscesses; replacing defective dental equipment; and endoscopic surgery to correct a Zenker diverticulum or gastrocolic fistula. Treating pseudo-halitosis involves reassurance. If significant concern persists despite reassurance, then referral to a mental health provider is indicated.