What causes fungal cheilitis?

How Fungal Cheilitis Develops

Fungal cheilitis (angular cheilitis with fungal involvement) develops when Candida species—normally present as oral commensals—overgrow at the corners of the mouth due to a combination of local moisture, mechanical factors, and compromised host defenses. 1, 2

Primary Causative Organism

• Candida albicans is the predominant fungal pathogen responsible for fungal cheilitis, though it often exists as part of normal oral flora in up to 40-65% of healthy individuals 3, 2
• Non-albicans species (C. glabrata, C. tropicalis, C. krusei) can also cause infection, particularly in refractory cases 1, 2
• Angular cheilitis frequently has a mixed bacterial and fungal etiology, not purely fungal 4

Local Predisposing Factors

The corners of the mouth provide an ideal environment for fungal overgrowth through several mechanisms:

• Denture wear creates moisture accumulation and mechanical irritation at the oral commissures, making this the single most significant local risk factor 2, 5
• Decreased salivation removes the protective antimicrobial properties of saliva that normally inhibit Candida overgrowth 3, 6
• Poor oral hygiene disrupts the normal balance of oral microflora 6, 5
• Mechanical factors including lip-licking, drooling, or deep facial folds that trap moisture at the angles of the mouth 7, 4
• Local irritation from climatic factors (cold, wind) or caustic agents 7

Systemic Predisposing Factors

Host immune compromise is critical for the transition from commensal colonization to pathogenic infection:

• Immunosuppression from HIV infection (especially CD4+ counts <200 cells/μL), malignancies (particularly hematologic cancers), or immunosuppressive medications 1, 2, 6
• Corticosteroid use, both systemic and inhaled formulations 1, 2
• Broad-spectrum antibiotic use disrupts normal bacterial flora that typically compete with and inhibit Candida 2, 6
• Diabetes mellitus creates a hyperglycemic environment favorable to fungal growth 3, 6
• Nutritional deficiencies (iron, B vitamins) compromise mucosal integrity 6, 7
• Advanced age represents a mild predisposing factor, with 84% of elderly long-term care residents colonized with yeast 2, 3

Pathophysiologic Mechanism

• Candida species normally exist as commensals but become pathogenic when the balance of oral microflora is disrupted or host defense mechanisms are compromised 1
• The organism demonstrates greater pathogenicity through enhanced adherence properties to damaged or macerated tissue at the oral commissures 3
• Moisture accumulation at the angles of the mouth creates the ideal microenvironment for fungal proliferation 5, 4
• The infection itself can further depress the host's immune system, creating a self-perpetuating cycle 3

Clinical Recognition

Angular cheilitis presents as:

• Inflammation, erythema, and fissuring at the corners of the mouth 1, 2
• Often accompanied by pain and discomfort 8
• May occur in conjunction with other forms of oral candidiasis (pseudomembranous or erythematous) 1, 8

Common Pitfall

The critical error is treating angular cheilitis as purely fungal without addressing underlying mechanical and moisture-related factors. 5, 7 Dentures must be disinfected, salivary function optimized, and nutritional deficiencies corrected—otherwise antifungal therapy alone will fail and recurrence is inevitable. 2, 5