Fluconazole

Generic Name: Fluconazole

Brand Names: Diflucan

Fluconazole is an antifungal medication used to treat yeast infections, including vaginal candidiasis, oral thrush, and systemic fungal infections.

AntifungalsInfectious Disease

Drug Class

Triazole Antifungal

Pregnancy

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)

What It's 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. 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

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.

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

Kidney Disease:

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

For a typical uncomplicated vaginal yeast infection, a single 150 mg oral dose is highly effective and works as well as a 7-day course of topical therapy. Symptom relief usually begins within 24 hours, with full resolution over a few days. Severe, recurrent, or non-albicans infections may require additional doses or a different agent.

Both treat Candida infections, but fluconazole is a systemic oral agent that distributes throughout the body, while topical azoles act locally. Oral fluconazole is more convenient for many patients, but it carries more systemic side effects and drug interactions and is not appropriate as a first choice during early pregnancy.

Mild, asymptomatic elevations of liver enzymes are common and often resolve on their own. Rarely, more significant liver injury can occur, particularly with prolonged or high-dose therapy. Report new fatigue, abdominal pain, dark urine, jaundice, or itching. For long courses, liver enzymes are typically monitored periodically.

A single short course usually does not require strict avoidance of alcohol, but combining alcohol with fluconazole can increase the risk of nausea and may add to the burden on the liver. For longer courses or in patients with liver disease, it is reasonable to abstain or limit intake.

Fluconazole can substantially increase the levels of certain statins (especially simvastatin and lovastatin) and raise the risk of muscle injury. For a brief single-dose treatment the risk is small, but longer courses warrant a discussion about pausing or switching the statin. Notify the prescribing clinician so dosing can be adjusted.

Questions to Ask Your Doctor

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?

Schedule an Appointment

Related Health Conditions

This medication is commonly used to treat or manage the following conditions:

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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.