Pronunciation: floo-con-a-zoll
Generic name: fluconazole
Brand name: Diflucan
Dosage form: oral tablet, oral suspension, injection for intravenous infusion
Drug class: Azole antifungals

Medically reviewed by Carmen Pope, BPharm. Last updated on Jul 9, 2024.

What is fluconazole?

Fluconazole is a prescription azole antifungal medication that may be used to treat serious fungal or yeast infections including those that affect the vagina, mouth or throat, lungs, bladder, or blood. It is available as an oral tablet, suspension, or injectable form.

• Examples of conditions treated by fluconazole include vaginal candidiasis, oropharyngeal candidiasis, esophageal candidiasis, and cryptococcal meningitis.

Fluconazole may also be used to prevent fungal infections in people with a weak immune system caused by cancer or cancer treatment including radiation therapy, bone marrow transplant, conditions such as AIDS, or children on life support (extracorporeal membrane oxygenation [ECMO]).

Fluconazole works by targeting a key enzyme (lanosterol 14-alpha-demethylase) responsible for building a crucial cell wall component (ergosterol) in fungi. By blocking this enzyme, Fluconazole prevents the fungus from forming a normal cell wall, leading to the buildup of abnormal sterols. These abnormal sterols weaken the fungal cell wall, hindering its growth. Fluconazole's mechanism of action means it has a much greater effect on this enzyme in fungi compared to the same enzyme in human cells. This selectivity helps minimize side effects.

Fluconazole was first FDA approved on January 29, 1990. Brand names for fluconazole include Diflucan and generic fluconazole is available.

What is fluconazole used for?

Fluconazole may be used to treat:

• Vaginal candidiasis (vaginal yeast infections due to Candida)
• Oropharyngeal and esophageal candidiasis
• Candida urinary tract infections and peritonitis
• Systemic Candida infections including candidemia, disseminated candidiasis, and pneumonia
• Cryptococcal meningitis.

Fluconazole may be used to prevent:

• Candidiasis in patients undergoing bone marrow transplantation who receive cytotoxic chemotherapy and/or radiation therapy
• Fungal infections in people with a weak immune system caused by cancer or cancer treatment including radiation therapy, conditions such as AIDS, or children on life support (extracorporeal membrane oxygenation [ECMO]).

It is recommended swabs or specimens for fungal culture and other laboratory tests be conducted before starting treatment with fluconazole; however, therapy may be started before the results of the cultures and other laboratory studies are known so long as anti-infective therapy is adjusted accordingly.

Related/similar drugs

nystatin, nystatin topical, clotrimazole topical, clotrimazole, ketoconazole, Diflucan, itraconazole

Fluconazole side effects

The most common side effects of fluconazole are:

• headache
• diarrhea
• nausea or upset stomach
• dizziness
• stomach pain
• changes in the way food tastes.

Serious side effects and warnings

Fluconazole can cause serious side effects including the following.

Allergic reactions to fluconazole. These are rare, but they can be serious and may include anaphylaxis. If you cannot reach your doctor, go to the nearest hospital emergency room. Signs of an allergic reaction can include shortness of breath; coughing; wheezing; fever; chills; throbbing of the heart or ears; swelling of the eyelids, face, mouth, neck, or any other part of the body; or skin rash, hives, blisters or skin peeling. 

Liver injury. Fluconazole has been associated with rare cases of serious liver toxicity, including death primarily in patients with serious underlying medical conditions including pre-existing liver disease. In some cases, there was no obvious relationship to the total daily dose, duration of therapy, sex, or patient age. Fluconazole liver toxicity has usually, but not always, been reversible once treatment has stopped. Tell your healthcare provider if you experience signs of liver problems which may include loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Skin conditions, including exfoliative skin disorders that have resulted in death in patients with serious underlying diseases, have been reported. Patients with deep-seated fungal infections who develop rashes during treatment with fluconazole should be monitored closely by a healthcare provider. Tell your doctor right away if you get a skin rash or lesions while taking fluconazole.

Cases of reversible adrenal insufficiency have been reported with fluconazole. Tell your doctor if you experience chronic, or long-lasting fatigue, muscle weakness, loss of appetite, weight loss, or abdominal pain.

Fluconazole may harm an unborn baby.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Before taking

Do not take fluconazole if you are allergic to fluconazole, Diflucan, other azole antifungals (such as ketoconazole, itraconazole, miconazole, or voriconazole), or any inactive ingredients in the fluconazole preparations.

Do not take fluconazole if you also take other medications known to prolong the QT interval and which are metabolized via the enzyme CYP3A4 such as erythromycin, pimozide, and quinidine.

Tell your healthcare provider about all your medical conditions including if you:

• have any liver problems
• have kidney disease
• have low levels of potassium in your blood
• have heart problems
• take any over-the-counter medicines you can buy without a prescription, including natural or herbal remedies
• are pregnant, or plan to become pregnant
• are breastfeeding.

The liquid form of fluconazole contains sucrose. Talk to your doctor before taking this form of fluconazole if you have a problem digesting sugars or milk.

Pregnancy

May harm an unborn baby. Women who can become pregnant should use effective birth control while using fluconazole and for at least 1 week after their last dose. Tell your doctor right away if you become pregnant.

Breastfeeding

Fluconazole can pass through breast milk to the baby. Talk to your doctor about the best way to feed your baby while taking fluconazole.

How should I take fluconazole?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

• Fluconazole oral tablets and liquid suspension are taken by mouth. Fluconazole injection is given as an infusion into a vein, usually by a healthcare provider.
• Use fluconazole for the prescribed length of time, even if your symptoms quickly improve.
• Skipping doses can increase your risk of infection that is resistant to medication.

Fluconazole will not treat viral infections such as the flu or common cold.

Call your doctor if your symptoms do not improve, or if they get worse.

Fluconazole oral

You may take fluconazole tablets or suspension with or without food.

• You can take fluconazole tablets or suspension at any time of the day.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Fluconazole injection

Fluconazole injection is given as an infusion into a vein.

• A healthcare provider will give your first dose and may teach you how to properly use the medication by yourself.
• Prepare an injection only when you are ready to give it.
• Do not use it if the medicine looks cloudy, has changed colors, or has particles in it. Call your pharmacist for new medicine.

Fluconazole dosage

The daily dose of fluconazole is the same for oral (tablets and suspension) and intravenous (IV) administration because the absorption of oral fluconazole is rapid and almost complete. 

• Oral fluconazole is usually preferred over IV unless the patient is unable to take oral medications or absorption or oral fluconazole from the gastrointestinal tract is likely to be compromised
• Fluconazole IV has been used safely for up to 14 days of intravenous therapy. Administer at a maximum rate of 200 mg/hour as a continuous infusion.

Your dose of fluconazole will depend on the infection you are treating.

• Vaginal infections are often treated with only one pill (fluconazole 150 mg as a single oral dose).
• For other infections, your first dose may be a double dose.
• Carefully follow your doctor's instructions.

Patients with impaired kidney function will need a dosage reduction if they are receiving multiple dosages of fluconazole. Refer to the Product Information.

Fluconazole dosage for oropharyngeal candidiasis

• Adults: Fluconazole 200 mg on the first day followed by 100 mg once daily.
• Children 6 months and older: fluconazole 6 mg/kg on the first day followed by 3 mg/kg once daily.
• Generally resolves within several days but treatment should be continued for at least 2 weeks to decrease the risk of relapse.

Fluconazole dosage for esophageal candidiasis

• Adults: Fluconazole 200 mg on the first day followed by 100 mg once daily. Dosages of up to fluconazole 400 mg/day may be used.
• Children 6 months and older: fluconazole 6 mg/kg on the first day followed by 3 mg/kg once daily. Dosages of up to 12 mg/kg/day may be used.
• Treat for a minimum of 3 weeks and at least 2 weeks after resolution of symptoms.

Fluconazole dosage for systemic candida infections (includes candidemia, disseminated candidiasis, and pneumonia)

• Adults: Optimal therapeutic dose and duration not established. Some trials have used dosages of up to 400 mg/day.
• Children: Dosage varies depending on age and gestational age. Refer to Fluconazole Product Information.
• Patients with systemic candidiasis should be treated for a minimum of 3 weeks and at least 2 weeks following the resolution of symptoms.

Fluconazole dosage for urinary tract infections and peritonitis

• Adults: Dosages of fluconazole 50 mg to 200 mg a day have been used.

Fluconazole dosage for cryptococcal meningitis

• Adults: Fluconazole 400 mg on the first day followed by 200 mg once daily.
  • A 400 mg/day dosage may be used based on medical judgment of the patient's response to therapy.
• Children: Fluconazole 12 mg/kg on the first day followed by 6 mg/kg once daily. Dosages of up to 12 mg/kg/day may be used.
• The recommended duration is 10 to 12 weeks after the cerebrospinal fluid becomes culture-negative.

Suppression of cryptococcal meningitis relapse in patients with AIDS

• Adults: Fluconazole 200 mg/day.
• Children: Fluconazole 6 mg/kg once daily.

Fluconazole dosage for prophylaxis in patients undergoing bone marrow transplantation

• Adults: Fluconazole 400 mg once daily.
• Patients who are anticipated to have severe granulocytopenia (less than 500 neutrophils cells/mm³) should start fluconazole injection prophylaxis several days before the anticipated onset of neutropenia, and continue for 7 days after the neutrophil count rises above 1000 cells/mm³.

Children on ECMO

• Children 3 months and older on ECMO: Fluconazole 35-mg/kg on the first day (not to exceed 800 mg) followed by 12-mg/kg once daily (not to exceed 400 mg).
• Children from birth to 3 months postnatal age, and gestational age less than 30 weeks: A loading dose of fluconazole 35 mg/kg on the first day followed by 9 mg/kg once daily is recommended.
• Children from birth to 3 months postnatal age, and gestational age 30 weeks and above: A loading dose of 35 mg/kg on the first day followed by 12 mg/kg once daily is recommended.

What happens if I miss a dose?

Take your dose as soon as you remember, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Overdose symptoms may include confusion or unusual thoughts or behavior.

What should I avoid while using fluconazole?

Avoid driving or hazardous activity until you know how fluconazole will affect you. Your reactions could be impaired.

Do not use fluconazole for a condition for which it was not prescribed.

Do not give fluconazole to other people, even if they have the same symptoms you have. It may harm them.

Many medications interact with fluconazole. Ask your doctor if your medication interacts.

What other drugs will affect fluconazole?

Other drugs may interact with fluconazole, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using. Fluconazole can cause serious problems if taken with certain medicines. Tell your doctor about all the medicines you take including:

• diabetes medicines such as glyburide, tolbutamide, glipizide
• blood pressure medicines like hydrochlorothiazide, losartan, amlodipine, nifedipine or felodipine
• blood thinners such as warfarin
• cyclosporine, tacrolimus or sirolimus (used to prevent rejection of organ transplants)
• rifampin or rifabutin for tuberculosis
• astemizole for allergies
• phenytoin or carbamazepine to control seizures
• theophylline to control asthma
• cisapride for heartburn
• quinidine (used to correct disturbances in heart rhythm)
• amiodarone (used for treating uneven heartbeats ‘arrhythmias’)
• amitriptyline or nortriptyline for depression
• pimozide for psychiatric illness
• amphotericin B or voriconazole for fungal infections
• erythromycin for bacterial infections
• olaparib, cyclophosphamide, or vinca alkaloids such as vincristine or vinblastine for the treatment of cancer
• fentanyl, afentanil or methadone for chronic pain
• halofantrine for malaria
• lipid-lowering drugs such as atorvastatin, simvastatin, and fluvastatin
• non-steroidal anti-inflammatory drugs including celecoxib, ibuprofen, and naproxen
• prednisone, a steroid used to treat skin, gastrointestinal, hematological or respiratory disorders
• antiviral medications used to treat HIV like saquinavir or zidovudine
• tofacitinib for rheumatoid arthritis
• vitamin A nutritional supplements.

Fluconazole can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV, such as erythromycin, astemizole, pimozide, quinidine, and cisapride.

Since there are many brand names for fluconazole, check with your doctor or pharmacist if you have any questions.

Many drugs can affect fluconazole, and some drugs should not be used at the same time. Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Storage

Store at room temperature away from moisture and heat. Do not freeze.

You may store the oral suspension between 86°F (30°C) and 41°F (5°C) but do not allow it to freeze. Throw away any leftover liquid that is more than 2 weeks old.

Keep out of reach of children and pets.

Who makes fluconazole?

Diflucan

Diflucan tablets and powder for oral suspension are made by Pfizer and distributed by Roerig, a division of Pfizer Inc.

Generic fluconazole

Various manufacturers such as Baxter Healthcare, Sagent Pharmaceuticals, and Hikma Pharmaceuticals USA Inc. make generic fluconazole injections.

Various manufacturers such as NorthStar Rx LLC, Slate Run Pharmaceuticals, and Aurobindo Pharma Limited make generic fluconazole powder for oral suspension.

Various manufacturers such as ANI Pharmaceuticals, Aurobindo Pharma Limited, and Dr Reddy’s Laboratories Limited make generic fluconazole tablets.

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