Diflucan (fluconazole) is a leading systemic antifungal medication indicated for the treatment and prophylaxis of various fungal infections. As a triazole antifungal agent, it operates through selective inhibition of fungal cytochrome P-450 sterol C-14 alpha-demethylation, effectively disrupting ergosterol synthesis—a critical component of fungal cell membranes. Its broad-spectrum activity, excellent oral bioavailability, and favorable safety profile make it a first-line therapeutic choice for both invasive and mucosal fungal infections in clinical practice. Healthcare providers value its predictable pharmacokinetics and demonstrated efficacy across diverse patient populations.

Features

• Active ingredient: Fluconazole 50 mg, 100 mg, 150 mg, 200 mg
• Pharmaceutical form: Film-coated tablets, powder for oral suspension, and intravenous solution
• Mechanism: Selective inhibition of fungal cytochrome P450-dependent enzymes
• Half-life: Approximately 30 hours (permitting once-daily dosing)
• Bioavailability: Over 90% following oral administration
• Protein binding: Low (11–12%)
• Renal excretion: Primarily unchanged in urine (approximately 80%)
• Pregnancy category: D (based on human data showing fetal harm)

Benefits

• Provides rapid symptomatic relief from fungal infections, often within 24–48 hours of initiation
• Offers convenient once-daily dosing regimen due to extended half-life, enhancing patient compliance
• Demonstrates excellent tissue penetration, including cerebrospinal fluid and ocular tissues
• Shows broad-spectrum activity against most clinically significant Candida species and Cryptococcus neoformans
• Presents lower toxicity profile compared to amphotericin B in appropriate clinical scenarios
• Available in multiple formulations allowing flexible administration routes based on clinical needs

Common use

Diflucan is clinically indicated for the treatment of oropharyngeal and esophageal candidiasis. It is also effective for systemic candidial infections, including urinary tract infections, peritonitis, candidemia, and disseminated candidiasis. The medication serves as first-line therapy for cryptococcal meningitis, both as acute treatment and maintenance therapy to prevent relapse in immunocompromised patients. Additionally, it is prescribed for the prevention of fungal infections in patients undergoing bone marrow transplantation who receive cytotoxic chemotherapy and/or radiation therapy. Vaginal candidiasis represents another common indication, typically treated with single-dose therapy. Off-label uses include treatment of certain dermatophytoses and prophylaxis in other immunocompromised populations.

Dosage and direction

Dosage must be individualized based on infection type, severity, and patient factors including renal function. For oropharyngeal candidiasis: 200 mg on first day followed by 100 mg once daily for minimum 14 days. Esophageal candidiasis: 200 mg on first day followed by 100 mg once daily; may increase to 400 mg daily if inadequate response, with treatment continuing for minimum 21 days. Systemic Candida infections: 400 mg on first day followed by 200 mg once daily; may increase to 400 mg daily based on clinical response. Cryptococcal meningitis: 400 mg on first day followed by 200–400 mg once daily for 10–12 weeks after cerebrospinal fluid becomes culture-negative. Maintenance therapy for cryptococcal meningitis in AIDS patients: 200 mg once daily. Vaginal candidiasis: Single 150 mg oral dose. Renal impairment requires dosage adjustment: For creatinine clearance less than 50 mL/min, reduce dose by 50%. Administration may occur with or without food. Tablets should be swallowed whole with water; oral suspension should be shaken well before each use.

Precautions

Hepatic function should be monitored during treatment, as rare cases of serious hepatic toxicity have been reported. Electrolyte balance, particularly potassium and magnesium levels, should be monitored in patients at risk of electrolyte imbalance. Caution is advised in patients with proarrhythmic conditions due to potential QT prolongation. Renal function should be assessed before initiation and periodically during therapy, with appropriate dosage adjustments implemented. Patients should be advised that dizziness or seizures may occur, requiring caution when operating machinery. Concomitant use with other hepatotoxic drugs increases risk of liver injury. Pregnancy should be avoided during treatment unless potential benefit justifies potential fetal risk. Breastfeeding is not recommended during therapy due to secretion in human milk. Pediatric use requires careful monitoring of liver function tests. Elderly patients often require dosage adjustment based on renal function.

Contraindications

Hypersensitivity to fluconazole, other azole antifungal agents, or any component of the formulation. Coadministration with cisapride due to potential for serious cardiovascular events, including QT prolongation, torsades de pointes, and sudden death. Concurrent use with terfenadine when Diflucan doses of 400 mg or greater are administered. Concomitant administration with drugs that prolong QT interval and are metabolized by CYP3A4, such as erythromycin, pimozide, and quinidine. Use in patients with congenital QT prolongation or known risk factors for torsades de pointes. Severe hepatic impairment without careful monitoring and consideration of alternative therapies. Combination therapy with voriconazole due to potential antagonistic antifungal effects.

Possible side effect

Common adverse reactions (≥1%) include headache (13%), nausea (7%), abdominal pain (6%), diarrhea (3%), dyspepsia (3%), dizziness (2%), and taste perversion (2%). Skin rash occurs in approximately 2% of patients. Less frequent but clinically significant effects include hepatotoxicity (elevated liver enzymes in 1–7%, clinical hepatitis <1%), exfoliative skin disorders including Stevens-Johnson syndrome (<0.1%), anaphylactic reactions (<0.1%), QT prolongation and torsades de pointes (rare), seizures (<0.5%), leukopenia (<1%), thrombocytopenia (<1%), and hypertriglyceridemia. Alopecia has been reported in approximately 1% of patients receiving long-term therapy. Cases of adrenal insufficiency have been documented with extended use.

Drug interaction

Diflucan significantly inhibits CYP2C9, CYP2C19, and CYP3A4 enzymes, resulting in numerous clinically important interactions. It increases concentrations of sulfonylureas (risk of hypoglycemia), warfarin (increased prothrombin time), phenytoin (increased levels requiring monitoring), cyclosporine (increased nephrotoxicity risk), theophylline (increased toxicity risk), rifabutin (increased uveitis risk), tacrolimus (increased nephrotoxicity), and statins (increased myopathy risk). Coadministration with rifampin decreases fluconazole concentrations by approximately 25%. Hydrochlorothiazide increases fluconazole concentrations by approximately 40%. Oral contraceptives maintain efficacy but breakthrough bleeding may occur. Interaction with vitamin K antagonists requires frequent INR monitoring. Concomitant use with other QT-prolonging agents increases arrhythmia risk.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is almost time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed administration. For once-weekly dosing regimens, if a dose is missed and remembered within 48 hours of the scheduled time, the dose should be taken immediately and the next dose taken on the originally scheduled day. If remembered more than 48 hours late, the patient should contact their healthcare provider for guidance. Consistency in dosing is important for maintaining therapeutic drug levels, particularly in the treatment of serious fungal infections.

Overdose

Cases of overdose have been reported with doses up to 8,200 mg. Symptoms may include pronounced nausea, vomiting, diarrhea, abdominal discomfort, and in severe cases, hallucinations and paranoid behavior. Seizures have been reported at doses above 1,200 mg. Treatment is primarily supportive and symptomatic. Gastric lavage may be considered if performed soon after ingestion. Activated charcoal may be administered to reduce absorption. Hemodialysis for three hours reduces plasma concentrations by approximately 50%, making it an effective intervention for significant overdose, particularly in patients with impaired renal function. ECG monitoring is recommended for at least 24 hours due to potential QT prolongation. Supportive care including antiemetics and seizure precautions should be implemented as needed.

Storage

Store tablets and oral suspension at controlled room temperature 20–25°C (68–77°F), with excursions permitted between 15–30°C (59–86°F). Protect from moisture and light. Keep container tightly closed. Do not freeze the oral suspension. Once reconstituted, the oral suspension is stable for 14 days at room temperature; do not refrigerate after reconstitution. Keep all medications out of reach of children and pets. Do not use beyond the expiration date printed on packaging. Do not transfer oral suspension to other containers. Intravenous solution should be stored at 5–30°C (41–86°F) and protected from freezing. Do not use if solution is discolored or contains particulate matter.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Healthcare professionals should consult official prescribing information before administering Diflucan. Patients must not make treatment decisions based on this information alone. Actual clinical use should be determined by a qualified healthcare provider considering individual patient factors. The manufacturer’s complete prescribing information contains additional details, warnings, and precautions. Serious infections require professional medical supervision. Only licensed healthcare providers can determine appropriate diagnosis and treatment strategies.

Reviews

Clinical studies demonstrate Diflucan’s efficacy in multiple settings. A randomized trial involving 221 patients with oropharyngeal candidiasis showed clinical cure rates of 81% with fluconazole versus 63% with clotrimazole. In esophageal candidiasis, endoscopic cure rates reached 91% with fluconazole compared to 52% with ketoconazole. For cryptococcal meningitis, combination therapy with fluconazole and flucytosine demonstrated superior efficacy to amphotericin B alone in certain patient populations. Maintenance therapy with fluconazole 200 mg daily reduced relapse rates from 37% to 4% in AIDS patients with cryptococcal meningitis. Vaginal candidiasis studies show single-dose 150 mg fluconazole produces clinical cure rates of 85–90% with mycological eradication in 70–80% of patients. Long-term safety data from over 4,000 patients confirms the generally favorable tolerability profile, with most adverse events being mild to moderate in severity.