Fluconazole
Fluconazole is an antifungal medication used to treat yeast infections, including vaginal candidiasis, oral thrush, and systemic fungal infections.
About Fluconazole
Fluconazole is a triazole antifungal also known by the brand name Diflucan. It is primarily used to fluconazole is prescribed to treat: • Vaginal yeast infections (candidiasis) • Oral and esophageal candidiasis (thrush) • Cryptococcal meningitis • Prevention of candidiasis in bone marrow transplant patients • Systemic candida infections • Urinary tract fungal infections • Peritonitis caused by Candida It's effective against a wide range of fungal infections. Fluconazole is available in oral tablet (50 mg, 100 mg, 150 mg, 200 mg), oral suspension (10 mg/ml, 40 mg/ml after reconstitution), and iv injection (200 mg/100 ml, 400 mg/200 ml premix bags) form. Healthcare providers commonly prescribe Fluconazole for conditions including Atrial Fibrillation, Hives (Urticaria), and Osteoarthritis.
Fluconazole at a Glance
- Brand names
- Diflucan
- Drug class
- Triazole Antifungal
- Pregnancy category
- FDA Category Category D for chronic high-dose use; single low-dose vaginal candidiasis treatment (150 mg) is generally considered low risk but is best avoided in the first trimester when an alternative topical antifungal can be used. Prolonged high-dose therapy (400–800 mg/day) during the first trimester has been associated with a distinct pattern of birth defects. Counsel patients to use effective contraception during high-dose courses.
- Available forms
- Oral tablet (50 mg, 100 mg, 150 mg, 200 mg), Oral suspension (10 mg/mL, 40 mg/mL after reconstitution), IV injection (200 mg/100 mL, 400 mg/200 mL premix bags)
- Therapeutic categories
- Antifungals, Infectious Disease
- Conditions treated
- 3 related conditions on this site
What Fluconazole Is Used For
Fluconazole is prescribed to treat:
• Vaginal yeast infections (candidiasis) • Oral and esophageal candidiasis (thrush) • Cryptococcal meningitis • Prevention of candidiasis in bone marrow transplant patients • Systemic candida infections • Urinary tract fungal infections • Peritonitis caused by Candida
It's effective against a wide range of fungal infections.
Dosage Quick Reference
These are general dosage guidelines for Fluconazole. Your doctor will determine the appropriate dose for your specific situation.
| Condition | Starting Dose | Maintenance Dose |
|---|---|---|
| Vaginal candidiasis (uncomplicated) | 150 mg orally as single dose | Repeat once after 72 hours for severe or recurrent episodes |
| Oropharyngeal candidiasis | 200 mg on day 1 | 100 mg orally daily for 7–14 days |
| Esophageal candidiasis | 200–400 mg on day 1 | 100–200 mg daily for at least 21 days and 14 days past symptom resolution |
| Cryptococcal meningitis (consolidation/maintenance) | 400 mg daily after induction | 200–400 mg daily; lifelong in some immunocompromised patients |
| Invasive candidiasis | 800 mg load (12 mg/kg) | 400 mg (6 mg/kg) daily for at least 14 days after first negative blood culture |
| Renal impairment (CrCl <= 50 mL/min, no dialysis) | Standard load | 50% of usual maintenance dose |
Side Effects
Common side effects may include:
• Headache • Nausea • Abdominal pain • Diarrhea • Dizziness • Changes in taste
Serious side effects (seek immediate medical attention):
• Severe allergic reactions • Liver problems (yellowing of skin/eyes, dark urine) • Severe skin reactions (Stevens-Johnson syndrome) • Irregular heartbeat (QT prolongation) • Seizures.com/what-is-epilepsy/seizure-types) • Adrenal insufficiency
See also: Drug Interactions ↓
Drug Interactions
Fluconazole is a potent inhibitor of CYP2C9 and CYP2C19 and a moderate inhibitor of CYP3A4. It also prolongs the QT interval. Drug interactions are common and clinically significant, even with short courses.
- Warfarin: Fluconazole markedly increases warfarin exposure via CYP2C9 inhibition, raising INR and bleeding risk. Monitor INR within 3–5 days of starting and consider preemptive warfarin dose reduction.
- Sulfonylureas (e.g., glyburide, glipizide, glimepiride): Increased plasma levels can cause prolonged hypoglycemia. Monitor blood glucose closely and consider holding or reducing the sulfonylurea.
- Phenytoin: Fluconazole raises phenytoin levels, potentially causing toxicity (ataxia, nystagmus, sedation). Check phenytoin levels and adjust dose.
- Statins (especially simvastatin and atorvastatin): Increased statin exposure raises the risk of myopathy and rhabdomyolysis. Pause simvastatin during fluconazole therapy when feasible; use lower doses or alternative statins (pravastatin, rosuvastatin) when continuation is necessary.
- QT-prolonging drugs (e.g., amiodarone, sotalol, citalopram, ondansetron, methadone): Co-administration increases torsades de pointes risk. Avoid combinations in patients with prolonged QT, electrolyte abnormalities, or structural heart disease.
- Tacrolimus, cyclosporine, sirolimus: Significant elevation of immunosuppressant levels with risk of nephrotoxicity. Monitor drug levels and reduce doses preemptively.
See also: Questions to Ask Your Doctor ↓
Key Considerations
Known drug interactions
Fluconazole has documented interactions with other medications, supplements, and certain foods. Review the Drug Interactions section below and tell your healthcare provider about every medication you take, including over-the-counter products. Jump to section →
Multiple forms available
Fluconazole comes in more than one form (Oral tablet (50 mg, 100 mg, 150 mg, 200 mg), Oral suspension (10 mg/mL, 40 mg/mL after reconstitution), IV injection (200 mg/100 mL, 400 mg/200 mL premix bags)). The right form for you depends on your condition, ease of use, and your provider's recommendation.
Additional Information
What is Fluconazole?
Fluconazole is a triazole antifungal medication widely used for treating and preventing various fungal infections. It's available as a single-dose treatment for vaginal yeast infections and for longer courses for more serious fungal infections.
How Does Fluconazole Work?
Fluconazole inhibits fungal enzyme cytochrome P450:
- Blocks ergosterol synthesis
- Disrupts fungal cell membrane formation
- Inhibits fungal growth and replication
- Fungistatic at lower doses
- Fungicidal at higher doses
Common Uses
- Vaginal Candidiasis: Single 150 mg dose
- Oral Thrush: 100-200 mg daily for 7-14 days
- Esophageal Candidiasis: 200 mg on day 1, then 100 mg daily for 2-3 weeks
- Cryptococcal Meningitis: Higher doses for extended periods
- Prophylaxis: In immunocompromised patients
Dosage and Administration
Vaginal Yeast Infection:
- Single 150 mg oral dose
- Can repeat in 3 days if needed
- Partner treatment usually not necessary
Oral Thrush:
- 200 mg on first day, then 100 mg daily
- Duration: 7-14 days
- Continue for at least 2 weeks
Systemic Infections:
- Higher doses (400-800 mg daily)
- Duration varies by infection and response
Administration Tips:
- Take with or without food
- Can be taken any time of day
- Oral suspension: shake well
Important Safety Information
Who Should Not Take Fluconazole?
- Hypersensitivity to fluconazole or other azoles
- Concurrent use with certain medications (see interactions)
- QT prolongation (use with caution)
Liver Toxicity Warning
⚠️ MONITOR LIVER FUNCTION:
- Rare but serious hepatotoxicity reported
- More common with longer treatment duration
- Monitor liver enzymes with prolonged use
- Stop if signs of liver damage
QT Prolongation
- Can prolong QT interval
- Risk of serious arrhythmias
- Use caution with:
- Heart disease
- Electrolyte imbalances
- Other QT-prolonging medications
Drug Interactions
Strong CYP Enzyme Inhibitor - Many Interactions:
Contraindicated With:
- Terfenadine (with doses >400 mg/day)
- Astemizole
- Cisapride
- Pimozide
- Quinidine
- Erythromycin
Significant Interactions:
- Warfarin (increased INR - monitor closely)
- Phenytoin (increased levels)
- Cyclosporine (increased levels)
- Tacrolimus (increased levels)
- Statins (increased muscle toxicity risk)
- Benzodiazepines (increased sedation)
- Oral hypoglycemics (increased hypoglycemia risk)
- Rifampin (decreased fluconazole effectiveness)
Pregnancy
- Avoid in pregnancy (Category D)
- High-dose, long-term use associated with birth defects
- Single low-dose for vaginal infection: unclear risk
- Use only if benefit outweighs risk
- Reliable contraception recommended
Breastfeeding
- Excreted in breast milk
- Single dose likely compatible
- Consider alternatives for prolonged therapy
Recurrent Vaginal Yeast Infections
If 4 or more infections per year:
- May need longer initial treatment
- Consider maintenance therapy: 150 mg weekly for 6 months
- Investigate underlying causes (diabetes, antibiotics, immunosuppression)
- Rule out other conditions
Resistance
Antifungal resistance can develop:
- More common in immunocompromised patients
- HIV/AIDS patients with frequent use
- May need alternative antifungals
- Culture and sensitivity testing helpful
Special Populations
Elderly:
- Dose adjustment based on kidney function
- Monitor closely for side effects
- Higher risk of drug interactions
- Dose reduction needed if CrCl <50 mL/min
- Loading dose same
- Reduce maintenance dose by 50%
Children:
- Safe for use in children
- Dose based on weight
- Commonly used for thrush in infants
Duration of Treatment
Varies by infection:
- Vaginal candidiasis: Single dose
- Oral thrush: 7-14 days
- Esophageal candidiasis: 2-3 weeks
- Cryptococcal meningitis: Months to years
- Prophylaxis: Duration of immunosuppression
When Treatment Fails
If symptoms persist:
- Confirm diagnosis (not all vaginitis is yeast)
- Rule out resistant strains
- Consider longer treatment
- Check blood glucose (diabetes)
- Evaluate for immunosuppression
- May need different antifungal
Monitoring
Monitor for:
- Liver function (with prolonged use)
- Kidney function
- Electrolytes (potassium, magnesium)
- Drug interactions
- Therapeutic response
- QT interval if at risk
Prevention of Yeast Infections
General measures:
- Avoid unnecessary antibiotics
- Control diabetes
- Wear cotton underwear
- Avoid douching
- Avoid irritating feminine products
- Probiotics may help (limited evidence)
When to Contact Your Doctor
- Symptoms not improving after 3 days
- Symptoms worsening
- Yellowing of skin or eyes
- Dark urine or pale stools
- Unusual fatigue or weakness
- Skin rash or blistering
- Irregular heartbeat
- Severe diarrhea
- Recurrent infections
Storage
- Store at room temperature
- Protect from moisture
- Keep oral suspension at room temperature
- Shake suspension well before use
- Do not freeze
Frequently Asked Questions
Questions to Ask Your Doctor About Fluconazole
Consider discussing these topics at your next appointment:
- Will any of my current medications interact with fluconazole?
- Do I need any blood tests during or after the course?
- Should I be using contraception during this course of fluconazole?
- How will we know the infection is fully treated, and what should I watch for if it returns?
- If symptoms come back frequently, what is the next step in evaluation?
Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.