What are the clinical features and recommended treatment of oral candidiasis (thrush)?

Oral Candidiasis (Thrush): Clinical Features and Treatment

Clinical Appearance

Oral thrush presents as white or yellowish-white patches on the oral mucosa that resemble milk curds or cottage cheese, most commonly affecting the tongue, buccal mucosa, palate, and gums. 1, 2

• The pseudomembranous form appears as thick, creamy white plaques that can be wiped off, leaving an erythematous or bleeding base underneath 1, 2
• Erythematous candidiasis presents as red, flat lesions without the white coating, often seen on the palate or dorsal tongue 1
• Angular cheilitis manifests as painful cracks and fissures at the corners of the mouth 1
• Denture-related candidiasis appears as diffuse erythema under denture-bearing areas 3

The infection occurs almost exclusively in compromised hosts with local factors (decreased salivation, denture wear) or systemic factors (diabetes, HIV/AIDS, immunosuppression, antibiotic use) 2, 1

Treatment Algorithm

Mild Disease

For mild oral thrush, start with topical antifungal therapy using clotrimazole troches 10 mg five times daily for 7-14 days. 3, 4

• Alternative: Miconazole mucoadhesive buccal 50-mg tablet applied once daily to the mucosal surface over the canine fossa for 7-14 days 3, 4
• Second-line alternatives: Nystatin suspension (100,000 U/mL) 4-6 mL four times daily OR nystatin pastilles (200,000 U each) 1-2 pastilles 4 times daily for 7-14 days 3, 4

Moderate to Severe Disease

For moderate to severe disease, oral fluconazole 100-200 mg daily for 7-14 days is the recommended first-line systemic therapy. 3, 4

• Fluconazole demonstrates 87-91% clinical cure rates compared to 32-52% with nystatin 5
• This represents the most effective treatment option with strong evidence 3, 4

Fluconazole-Refractory Disease

If the patient fails to respond to fluconazole after 7-14 days, switch to itraconazole oral solution 200 mg once daily OR posaconazole suspension 400 mg twice daily for 3 days, then 400 mg daily, for up to 28 days. 3, 4

• Alternative options include voriconazole 200 mg twice daily OR amphotericin B deoxycholate oral suspension 100 mg/mL four times daily 3, 4
• For severe refractory cases requiring parenteral therapy: IV echinocandin (caspofungin 70-mg loading dose, then 50 mg daily; micafungin 100 mg daily; or anidulafungin 200-mg loading dose, then 100 mg daily) 3, 4

Special Clinical Situations

Denture-Related Candidiasis

Disinfection of dentures is mandatory in addition to antifungal therapy for definitive cure. 3, 4

• Antifungal therapy alone will fail without proper denture hygiene 4

HIV-Infected Patients

Initiate or optimize antiretroviral therapy to reduce recurrent infections, as this is the most important intervention. 3, 4

• For recurrent infections despite ART, use chronic suppressive therapy with fluconazole 100 mg three times weekly 3, 4
• HIV patients with CD4 counts <200 cells/μL are at highest risk 3

NPO Patients

If the patient cannot take oral medications (e.g., NPO for DKA), switch immediately to IV fluconazole 100-200 mg daily. 5

• Topical agents like nystatin are completely ineffective when NPO as they require direct mucosal contact and swallowing 5
• IV fluconazole achieves identical therapeutic levels as oral dosing 5

Critical Pitfalls to Avoid

Complete the full 7-14 day course even if symptoms resolve quickly, as premature discontinuation leads to recurrence. 6, 4

• Azole-refractory infections are more common in patients with prior azole exposure and severe immunosuppression 4
• Oropharyngeal fungal cultures have limited utility as many healthy individuals have asymptomatic colonization; diagnosis is primarily clinical 4, 2
• In immunocompromised patients, untreated oropharyngeal candidiasis can spread to the bloodstream or esophagus, causing potentially lethal systemic infection 1
• Monitor for fluconazole-clopidogrel interaction in cardiac patients, as fluconazole inhibits CYP2C19 and reduces clopidogrel's antiplatelet effect; consider IV echinocandin instead 5
• Baseline CBC monitoring is not required before initiating oral antifungal therapy for oral candidiasis in immunocompetent patients 6