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Fluconazole: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Aug 17, 2022.

1. How it works

  • Fluconazole may be used to treat fungal infections.
  • Fluconazole works by inhibiting an enzyme in fungi, called lanosterol 14-α-demethylase, responsible for the conversion of lanosterol, a type of fat, to ergosterol. This interferes with the formation of the fungal cell membrane.
  • Fluconazole belongs to the class of medicines known as triazole antifungals.

2. Upsides

  • May be used to treat certain fungal or yeast infections.
  • May be used to treat vaginal candidiasis (vaginal yeast infections caused by Candida yeasts).
  • Effective for other Candida infections such as those of the esophagus and mouth, urinary tract infections, peritonitis, and systemic infections.
  • May be used to treat Cryptococcal meningitis in AIDS patients.
  • May be used as a preventative measure to reduce the risk of candidiasis in people undergoing bone marrow transplantation receiving chemotherapy or radiotherapy.
  • Effective against Candida albicans, C. glabrata (many strains have only intermediate susceptibility), C. parapsilosis, C. tropicalis, Cryptococcus neoformans, and several other Candida species.
  • One single oral dose is usually sufficient to treat vaginal candidiasis.
  • Can be given as a single daily dose.
  • The absorption of fluconazole is not affected by food.
  • Does not appear to affect the absorption of oral contraceptives.
  • Usually well-tolerated.
  • Generic fluconazole is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • A headache, nausea, abdominal pain, diarrhea, indigestion, and dizziness. The incidence of gastrointestinal side effects is high with single-dose therapy. Anaphylaxis and a rash have been reported rarely.
  • In some people, fluconazole may cause dizziness and affect their ability to drive a car or operate machinery. Avoid alcohol.
  • Specimens or swabs should be taken before fluconazole is initiated. However, therapy may be started before the results of the culture is known if the causative organism is presumed to be one sensitive to fluconazole. Once the results are known, adjust anti-infective therapy accordingly.
  • Candida Krusei is considered resistant to fluconazole and there have been reports of superinfection with this yeast in people being treated with fluconazole.
  • There is a lack of data regarding the use of single-dose fluconazole therapy in pregnant women; however, the data available do not suggest an increased risk of birth defects in the fetus in women who have taken a single dose of fluconazole.
  • May not be suitable for some people including those with a weakened immune system, diabetes, cancer, or low blood potassium or magnesium levels. The dosage of fluconazole may need to be reduced in people with kidney disease (does not apply to single-dose therapy).
  • Caution should be exercised when administering fluconazole to people with liver disease. Rarely, serious, potentially fatal, liver damage may occur. The risk is higher in people with serious underlying diseases.
  • May cause cardiotoxicity and QT prolongation. The risk is greater in people who are seriously ill, with structural heart disease, electrolyte abnormalities, or taking other medications that also prolong the QT interval.
  • May interact with several medicines including warfarin, oral hypoglycemics, terfenadine, ergotamine, pimozide, herbal supplements, and other anti-infectives. Fluconazole should not be given with erythromycin. The enzyme inhibiting effect of fluconazole persists for 4 to 5 days after discontinuation of fluconazole.
  • Although single-dose fluconazole is effective for vaginal yeast infections, there is a higher risk of adverse reactions (26%) versus intravaginal agents (16%).
  • There are no adequate and well-controlled trials regarding the use of fluconazole in pregnant women. Weigh up risks versus benefits before using during pregnancy.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

  • Fluconazole is an effective antifungal agent that may be used to treat certain fungal or yeast infections. Side effects include headache, nausea, abdominal pain, diarrhea, indigestion, and dizziness. It can be given as a single dose for vaginal candidiasis. Fluconazole interacts with several medicines including warfarin, oral hypoglycemics, terfenadine, ergotamine, pimozide, herbal supplements, and other anti-infectives.

5. Tips

  • May be taken with or without food.
  • Take exactly as directed by your doctor. Ensure you finish the course as prescribed by your doctor. Try to take fluconazole at the same time each day if you are taking fluconazole for more than one day.
  • Take fluconazole at least two hours before medications are given for GERD or acid reflux such as proton pump inhibitors (for example omeprazole).
  • Fluconazole may occasionally cause dizziness which may affect your ability to drive or operate machinery. Do not perform hazardous tasks if fluconazole affects you in this way.
  • See your doctor if you develop an irregular heart rhythm, yellowing of the skin, persistent abdominal pain, or any other worrying side effect after taking fluconazole.
  • Do not take any other medications including those bought over the counter without first checking with your doctor or pharmacist that these are compatible with fluconazole.
  • Tell your doctor if you are breastfeeding, pregnant, or intending to become pregnant because fluconazole may not be suitable for you.

6. Response and effectiveness

  • Peak levels of fluconazole are reached within one to two hours of oral administration. However, signs of infection may take longer to abate. Fluconazole has a long half-life and single-dose therapy or once-daily dosing is usually sufficient for most infections.
  • Fluconazole is rapidly and completely absorbed after oral administration.
  • A single oral 150mg dose penetrated into vaginal tissue resulting in tissue: plasma ratios ranging from 0.94 to 1.14 over the first 48 hours following dosing.

7. Interactions

Medicines that interact with fluconazole may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with fluconazole. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with fluconazole include:

  • anticoagulants or antiplatelet agents (blood thinners), such as warfarin, and clopidogrel (may prolong bleeding time)
  • biologics, such as acalabrutinib, bosutinib, or entrectinib
  • albuterol
  • antibiotics, such as ciprofloxacin, erythromycin, or moxifloxacin
  • anticonvulsants, such as carbamazepine or phenytoin
  • antidepressants, such as amitriptyline, citalopram, clomipramine, desipramine, duloxetine, escitalopram, imipramine, or nortriptyline
  • antifungals, such as voriconazole
  • antipsychotics, such as clozapine, haloperidol, thioridazine, or ziprasidone
  • aprepitant
  • barbiturates, such as phenobarbital
  • benzodiazepines, such as midazolam or triazolam
  • buspirone
  • cannabidiol
  • cisapride
  • cocaine
  • colchicine
  • corticosteroids, such as fludrocortisone or prednisone
  • diabetes medications, such as glimepiride, glyburide, or glipizide
  • diuretics, such as furosemide or hydrochlorothiazide
  • droperidol
  • estrogens or progestins
  • famotidine
  • heart medications, such as amiodarone, felodipine, sotalol, quinidine, or procainamide
  • HIV medications, such as efavirenz or saquinavir
  • lithium
  • medications to lower cholesterol, such as atorvastatin or simvastatin
  • mifepristone
  • migraine medications, such as dihydroergotamine
  • nilotinib
  • omeprazole
  • ondansetron
  • opioids, such as alfentanil, fentanyl, oxycodone, methadone, morphine, or codeine
  • pimozide
  • polyethylene glycol 3350
  • red yeast rice
  • tacrolimus
  • tamoxifen
  • tramadol
  • ziprasidone
  • zolpidem.

Note that this list is not all-inclusive and includes only common medications that may interact with fluconazole. You should refer to the prescribing information for fluconazole for a complete list of interactions.


Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use fluconazole only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2023 Revision date: August 17, 2022.