Fluconazole

What fluconazole is and how it works

Fluconazole is an antifungal medicine that works by blocking an enzyme fungi need to build their cell membranes. It treats a range of fungal (mainly Candida yeast) infections, from vaginal thrush treated with a single dose, to serious infections such as cryptococcal meningitis that need weeks of higher-dose treatment. (1) (2)

For the common single-dose vaginal thrush use, fluconazole is generally very well tolerated. For higher doses or longer courses, it has real, serious interactions with several other medicines and a small risk of liver problems and heart-rhythm changes, so it is important to tell your prescriber or pharmacist about every other medicine you take before starting it.

Mechanism of action: how fluconazole works

Fluconazole is a triazole antifungal that selectively inhibits fungal cytochrome P450-dependent 14-alpha-demethylase, blocking conversion of lanosterol to ergosterol, an essential component of the fungal cell membrane. It is also a moderate inhibitor of human CYP2C9 and CYP3A4 and a strong inhibitor of CYP2C19, the basis for its numerous, clinically significant drug interactions. (1) (2)

What is Fluconazole used for?

Before taking fluconazole

Do not take / not appropriate for

• Do not take fluconazole if you have a known allergy to it or to other azole antifungal medicines. (all countries) (1) (2)
• Do not take fluconazole together with quinidine, pimozide, cisapride, astemizole, or erythromycin -- these combinations are contraindicated because of a serious risk of dangerous heart rhythm changes. (all countries) (1) (2)
• Do not take terfenadine together with fluconazole at repeated (multiple) fluconazole doses of 400 mg per day or higher. (all countries) (1) (2)

Tell your clinician about

• All other medicines you take -- fluconazole has real, sometimes significant interactions with many common medicines, including warfarin, some diabetes tablets, phenytoin, ciclosporin, tacrolimus, and midazolam.
• Any personal or family history of an irregular heart rhythm, or low blood potassium.
• Any history of liver problems.
• Whether you are pregnant, planning pregnancy, or breastfeeding.
• Whether you have had 4 or more episodes of vaginal thrush in the past year, since this may need a different, longer treatment course.

Fluconazole dosage and how to take it

• Take fluconazole exactly as directed for your specific infection -- the dose, strength, and length of treatment vary widely depending on what is being treated.
• For the standard single-dose vaginal thrush treatment, only one capsule is needed; for other uses, complete the full course even if you feel better sooner.
• If your kidneys do not work normally, your prescriber may adjust your dose.

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5)

Missed dose

For a single-dose treatment, this does not apply. For a multi-dose course, if you miss a dose, take it as soon as you remember unless it is nearly time for your next dose -- do not take an extra dose. Contact your pharmacist or prescriber if you are unsure.

Overdose

Seek urgent medical attention if you think you have taken too much fluconazole, particularly if you develop an irregular heartbeat, severe dizziness, or fainting. Reported overdose symptoms have included hallucinations and paranoid behaviour; supportive care and, if needed, haemodialysis can help remove the drug. (2)

Fluconazole side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Serious warnings

Interactions

• Warfarin and other coumarin-type anticoagulants: fluconazole can prolong prothrombin time (increase bleeding-test results) up to 2-fold -- closer monitoring is needed. (1) (2)
• Oral diabetes medicines (sulfonylureas): fluconazole can cause clinically significant low blood sugar; one fatality has been reported. (1)
• Phenytoin, ciclosporin, and tacrolimus: fluconazole significantly raises blood levels of these medicines, requiring dose adjustment and monitoring under specialist care. (1) (2)
• Midazolam and other benzodiazepines taken by mouth: fluconazole markedly increases their levels and effects. (2)
• Amiodarone and other QT-prolonging medicines: combining with fluconazole may increase the risk of a dangerous heart rhythm change. (1)
• Voriconazole and abrocitinib: avoid combining with fluconazole. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Monitoring

Before starting

• Review of all other medicines for interactions (especially warfarin, sulfonylureas, phenytoin, ciclosporin, tacrolimus, midazolam, and other QT-prolonging drugs)
• Kidney function, if a longer course is planned
• Baseline liver function, if a longer course or higher dose is planned

During treatment

• Liver function tests if treatment is prolonged or symptoms of liver problems develop.
• Blood potassium and heart rhythm monitoring in higher-risk patients on longer or higher-dose courses.

Storage

Store at room temperature, protected from moisture, out of reach of children, following the specific product's packaging instructions.

Frequently asked questions

References

1. DIFLUCAN (fluconazole) -- FDA prescribing informationU.S. Food and Drug Administration prescribing information (mirrored in full by drugs.com's FDA-label reproduction; the underlying document is Pfizer's FDA-approved DIFLUCAN/fluconazole label) · United States · accessed 2026-07-30 · source 1
2. Diflucan 150 mg hard capsules -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Pfizer Limited · United Kingdom · accessed 2026-07-30 · source 2
3. Fluconazole -- consumer medicine informationHealthify (New Zealand government-funded consumer health information service, referencing Medsafe datasheets/CMI) · New Zealand · accessed 2026-07-30 · source 3
4. Fluconazole -- international brand namesDrugs.com International Drug Names database (a real, maintained secondary compilation of international brand names; NOT a primary regulator source -- used only to corroborate brand-name presence, not clinical claims) · Canada, Australia, New Zealand, United Kingdom, European Union (general) · accessed 2026-07-30 · source 4
5. Fluconazole -- regulatory scheduling contextGeneral encyclopaedia entry (tertiary source, used only for general scheduling/context corroboration, never as evidence of a specific clinical claim) · General/multi-country · accessed 2026-07-30 · source 5

Brand names by country

Single-ingredient fluconazole names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries