Fluconazole - Use | Dose | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Fluconazole is a drug from the group of triazole antifungal medications. It inhibits the fungal demethylation of 14- alpha-lanosterol mediated by cytochrome P450, which leads to the accumulation of a 14-alpha-methyl sterols in the fungi which further leads to their death. Fluconazole has a selectivity for fungal cytochrome P450 enzyme compared with the same enzyme in mammals. It is used to treat a number of fungal infections.


Fluconazole is contraindicated in the following situations:

  • In patients who are hypersensitive to azoles
  • In patients who are taking drugs, such as:
    • terfenadine
    • astemizole (antihistamines)
    Concomitant use with these drugs significantly increases the risk of QT prolongation and arrhythmia.

Fluconazole should not be used in the treatment of tinea capitis (fungal infection of the scalp, eyebrows and eyelashes) in children because it has low success rate in treating this infection.

Fluconazole should be used with caution in patients with impaired renal or hepatic function.

Fluconazole should be administered cautiously in patients who have a predisposition for arrhythmias, because some studies suggest that this drug prolongs the QT interval.

Fluconazole rarely causes Stevens-Johnson syndrome (a severe skin disease), which occurs more frequently in patients who have AIDS. Therefore, it must be applied very cautiously in such patients.

Fluconazole, pregnancy and breastfeeding

Fluconazole belongs to the group D according to FDA and AU TGA classifications. This means that the risk of congenital anomalies is proved and that this drug should never be used during pregnancy.

Avoid breastfeeding while taking this medicine.


Dosage mostly depends on the type and severity of the infection. The usual dosage range is 200-400 mg per day. Your doctor will determine which dose is right for you. The duration of treatment is from several weeks to one year.

It is necessary to adjust the dose in patients with impaired renal function. Patients whose creatinine clearance is less than 50 ml / min should take half of the recommended dose.

In children doses greater than 400 mg should not be applied.

Fluconazole can be administered orally (capsule), or intravenously (as an intravenous infusion).

If you are taking capsules, you should know that you can take them regardless of food.


Fluconazole enter in about 150 major interactions. Some of them are given below:

  • Astemizole and terfenadine. Co-administration may lead to arrhythmia.
  • Anti-coagulants (e.g. anisindione). Co-administration may lead to easy bleeding.
  • Fentanyl, alfentanil and hydrocodone (analgesics). Fluconazole increases the concentration of these drugs in the blood, which lead to drowsiness, bradycardia and shortness of breath.
  • Immunomodulatory agents (e.g. leflunomide). Taking these drugs together can lead to liver damage and to the onset of symptoms, such as:
    • loss of appetite
    • dark colored urine
    • light colored stools and jaundice
  • Amiodarone (a drug used to treat arrhythmias).
  • Avanafil (a drug used in the treatment of erectile dysfunction). Taking these two drugs together, may cause low blood pressure, chest pain, tinnitus, and priapism (prolonged, painful erection).
  • Atorvastatin (a drug that lowers high cholesterol). Taking these two drugs together increases the risk of rhabdomyolysis.
  • Anagrelide (a drug used for lowering platelet count in the blood). Taking these two drugs together increases the risk of arrhythmia.
  • Suvorexant (a drug used to treat insomnia). Taking these two drugs together can lead to the increased sedation, hallucinations and difficulty breathing.
  • Bepridil (a drug used for the treatment of angina and hypertension). Taking these two drugs together increases the risk of arrhythmia.
  • Sotalol (a beta-blocker used in the treatment of heart disease). Taking these two drugs together increases the risk of arrhythmia.
  • Ergotamine (a drug used in the treatment of migraine). Fluconazole increases the concentration of ergotamine in the blood, which can lead to severe vasoconstriction and thus lead to a heart attack!
  • Prednisone
  • Zidovudine
  • Theophylline
  • Vitamin A supplements
  • Oral contraceptives

Tell your doctor about all medicines you are taking, because this drug interacts with many drugs.

Adverse reactions

Possible adverse effects of the fluconazole include:

  • Loss of appetite, nausea and vomiting
  • Swelling of the eyelids
  • Wheezing
  • Insomnia or drowsiness
  • Liver damage
  • Constipation
  • Hypokalemia
  • Alopecia
  • Hypercholesterolemia
  • Allergy

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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