White Patches on the Tongue: Causes
White patches on the tongue are most commonly caused by oral thrush (oral candidiasis), a fungal infection caused predominantly by Candida albicans, which occurs when normal oral flora is disrupted by immunosuppression, diabetes, antibiotic use, or corticosteroid therapy. 1, 2
Primary Causative Organism
- Candida albicans is responsible for the vast majority of oral thrush cases, accounting for most infections and existing as a commensal organism in the oral cavity of up to two-thirds of healthy individuals. 3, 2
- Non-albicans Candida species including C. glabrata, C. dubliniensis, C. krusei, and C. tropicalis can also cause white patches, particularly in refractory cases or after repeated azole exposure. 3, 2, 4
Key Risk Factors in Immunocompromised Patients
Immunosuppression-Related Causes
- HIV/AIDS with CD4 counts <50-200 cells/μL is a major predisposing factor, with approximately 30% of HIV-positive patients developing oral candidiasis. 3, 4
- Diabetes mellitus increases risk through impaired glycemic control, local immunosuppression, and altered host defenses. 3, 5
- Immunosuppressive medications (transplant drugs, chemotherapy) significantly increase susceptibility to Candida overgrowth. 3, 4
Medication-Induced Causes
- Corticosteroid use, both systemic and inhaled formulations, disrupts local immune defenses and promotes fungal overgrowth. 4, 5
- Broad-spectrum antibiotic therapy eliminates competing bacterial flora that normally inhibit Candida proliferation. 2, 5
Local Oral Factors
- Denture use creates an environment conducive to Candida growth, with 84% of elderly long-term care residents colonized with yeast. 2
- Poor oral hygiene and decreased salivation allow fungal overgrowth. 6
Clinical Presentation Patterns
The Infectious Diseases Society of America recognizes three main clinical patterns: 1, 4
- Pseudomembranous candidiasis (classic thrush): Creamy white, plaque-like lesions on buccal mucosa, tongue, or oropharynx that can be scraped off, often revealing bleeding underneath. 1, 5
- Erythematous candidiasis: Red patches without white plaques, typically on the palate or tongue. 1, 4
- Angular cheilitis: Inflammation and cracking at the corners of the mouth. 1, 5
Important Clinical Pitfalls
- Failure to identify underlying predisposing factors leads to treatment failure in 20-30% of cases—always investigate diabetes, HIV status, medication history, and denture use. 1
- Esophageal involvement should be suspected in patients with oral thrush who report difficulty swallowing, retrosternal pain, or odynophagia, occurring in 10-20% of cases. 1
- Resistance development occurs in 10-20% of immunocompromised patients with prolonged or repeated fluconazole exposure, particularly with CD4 counts <50 cells/μL. 3, 1, 4
- Non-albicans species emergence (5-10% of cases) should be considered in refractory disease, as these organisms may have intrinsic azole resistance. 1, 4
Other Differential Considerations
While Candida is the predominant cause, rare non-Candidal fungi can occasionally present as white oral lesions in severely immunocompromised patients, though these typically represent disseminated systemic disease rather than isolated oral pathology. 6, 7