What is the recommended dosage of Diflucan (fluconazole) for treating fungal infections?

Oral Fluconazole Dosing for Fungal Infections

The recommended dosage of oral fluconazole varies by infection type: 200 mg on day 1 then 100 mg daily for oropharyngeal candidiasis, 200-400 mg daily for esophageal candidiasis, 400 mg daily for candidemia, and 200 mg daily for symptomatic urinary tract infections. 1, 2

Oropharyngeal Candidiasis

For moderate to severe oropharyngeal candidiasis, use fluconazole 100-200 mg daily for 7-14 days. 3, 4

• The standard regimen is 200 mg on the first day, followed by 100 mg once daily for 7-14 days 1, 2
• Topical agents (clotrimazole troches 10 mg 5 times daily or miconazole buccal tablets) are preferred first-line for mild disease 1, 3, 4
• Treatment should continue for at least 2 weeks to decrease relapse likelihood 2
• For fluconazole-refractory disease, switch to itraconazole solution 200 mg once daily or posaconazole suspension 400 mg twice daily for 3 days then 400 mg daily 1

Esophageal Candidiasis

For esophageal candidiasis, use 200 mg on day 1, then 100 mg once daily for 14-21 days, with doses up to 400 mg daily for severe cases. 1, 2

• The standard dose is 200-400 mg (3-6 mg/kg) daily for 14-21 days 3, 4
• Treatment should continue for a minimum of 3 weeks and at least 2 weeks following symptom resolution 2
• Higher doses (up to 400 mg daily) may be used based on clinical response 3, 2

Systemic Candida Infections (Candidemia)

For candidemia and disseminated candidiasis, use 400 mg (6 mg/kg) daily after an 800 mg loading dose. 3, 5, 4

• A loading dose of twice the daily dose (800 mg or 12 mg/kg) is recommended on day 1 to achieve near-steady-state concentrations by day 2 5, 2
• Continue treatment for 2 weeks after blood cultures become negative and symptoms resolve 3
• Central venous catheter removal is strongly recommended in candidemia cases 3

Urinary Tract Infections

For symptomatic Candida cystitis, use 200 mg (3 mg/kg) daily for 2 weeks. 1, 4

• For Candida pyelonephritis, increase to 200-400 mg (3-6 mg/kg) daily for 2 weeks 3, 4
• Elimination of indwelling bladder catheters is strongly recommended whenever feasible 1
• Treatment is NOT recommended for asymptomatic candiduria unless the patient is neutropenic, a very low-birth-weight infant (<1500 g), or undergoing urologic manipulation 1

Vaginal Candidiasis

For uncomplicated vaginal candidiasis, use a single 150 mg oral dose. 2

• This single-dose regimen is as effective as standard topical azole therapy 6
• Topical antifungal agents remain an alternative option with no single agent superior to another 1

CNS Infections (Cryptococcal Meningitis)

For step-down therapy after initial amphotericin B treatment of cryptococcal meningitis, use fluconazole 400-800 mg (6-12 mg/kg) daily. 1

• Initial treatment should be liposomal amphotericin B 5 mg/kg daily with or without flucytosine 1
• Continue therapy until all signs, symptoms, CSF abnormalities, and radiological findings resolve 1
• For suppression of relapse in AIDS patients, use 200 mg once daily 2

Critical Resistance Considerations

Fluconazole has no activity against Candida krusei and variable activity against C. glabrata—alternative antifungals must be used for these species. 5, 4

• For fluconazole-resistant C. glabrata, use amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days OR oral flucytosine 25 mg/kg 4 times daily 1
• For C. krusei, use amphotericin B deoxycholate 0.3-0.6 mg/kg daily for 1-7 days 1
• Resistance can develop particularly in patients with recurrent or chronic infections 3

Pediatric Dosing Equivalents

Pediatric dosing: 3 mg/kg approximates 100 mg in adults; 6 mg/kg approximates 200 mg in adults. 3, 2

• Some older children may have clearances similar to adults 2
• Absolute doses exceeding 600 mg/day are not recommended in pediatric patients 2

Common Pitfalls

• Do not treat Candida isolated from respiratory secretions—this usually represents colonization rather than infection and rarely requires antifungal therapy 3, 4
• Oral and IV dosing are equivalent due to rapid and almost complete oral absorption 2
• Inadequate treatment duration may lead to recurrence of active infection 2
• AIDS patients with cryptococcal meningitis or recurrent oropharyngeal candidiasis require maintenance therapy to prevent relapse 2