What is the dose of intravenous (IV) fluconazole for fungal infections?

Intravenous Fluconazole Dosing for Fungal Infections

For most invasive Candida infections, use IV fluconazole 400 mg (6 mg/kg) daily, with a loading dose of 800 mg (12 mg/kg) on day 1 for severe infections. 1

Dosing by Infection Type

Esophageal Candidiasis

• Standard dose: 200-400 mg (3-6 mg/kg) IV daily for 14-21 days 1
• For patients unable to tolerate oral therapy, use 400 mg (6 mg/kg) IV daily 1
• Alternative: Echinocandin (micafungin 150 mg daily, caspofungin 70 mg loading then 50 mg daily, or anidulafungin 200 mg daily) 1

Oropharyngeal Candidiasis (Moderate to Severe)

• Oral preferred: 100-200 mg daily for 7-14 days 1
• IV alternative for refractory disease: Amphotericin B deoxycholate 0.3 mg/kg daily 1

Candidemia and Invasive Candidiasis

• Systemic infections: 200-400 mg IV daily, though optimal dosing not fully established 2
• Duration: Continue until clinical parameters and laboratory tests indicate resolution of active infection 2
• Important: Inadequate treatment duration leads to recurrence 2

CNS Candidiasis

• Dose: 400-800 mg (6-12 mg/kg) IV daily for patients unable to tolerate amphotericin B 1
• Continue until all signs, symptoms, CSF abnormalities, and radiologic findings resolve 1
• Remove intraventricular devices if present 1

Urinary Tract Infections

• Symptomatic cystitis: 200 mg (3 mg/kg) daily for 14 days 1
• Pyelonephritis: 200-400 mg (3-6 mg/kg) daily for 14 days 1
• Treat as candidemia if disseminated candidiasis suspected 1

Cryptococcal Meningitis

• Acute treatment: 400 mg IV on day 1, then 200 mg daily 2
• May increase to 400 mg daily based on response 2
• Duration: 10-12 weeks after CSF becomes culture-negative 2
• Consolidation: 400-600 mg daily for 8 weeks 1
• Maintenance (AIDS patients): 200 mg daily for 6-12 months 1, 2

Non-Meningeal Cryptococcosis

• Severe disease: Treat as CNS disease for 12 months 1
• Mild-to-moderate: 400 mg daily for 6-12 months 1

Chronic Disseminated Candidiasis

• Continue treatment until lesions resolve (typically 3-6 months) 1
• Fluconazole can be used as step-down therapy in stable patients 1

Key Dosing Principles

Loading Dose Strategy

• General principle: Use a loading dose of twice the daily dose on day 1 to achieve near-steady-state concentrations by day 2 2
• This applies to all serious infections requiring rapid therapeutic levels 2

Route Equivalence

• IV and oral doses are identical due to rapid and nearly complete oral absorption 2
• Switch to oral when patient can tolerate and clinical stability achieved 1

Special Populations

• Neonates: 12 mg/kg/day for candidiasis 1
• Bone marrow transplant prophylaxis: 400 mg daily, starting several days before anticipated neutropenia, continuing 7 days after neutrophil count >1000 cells/mm³ 2

Common Pitfalls

• Underdosing severe infections: Many clinicians use 200 mg when 400 mg is indicated for invasive disease 1
• Inadequate duration: Stopping too early leads to relapse; continue until clinical and laboratory resolution 2
• Not adjusting for renal function: Fluconazole requires dose reduction in renal impairment 2
• Species-specific resistance: C. krusei is intrinsically resistant; C. glabrata often has reduced susceptibility—consider echinocandin instead 1