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Fluconazole (Diflucan)

What is fluconazole?

Fluconazole (brand name Diflucan) is an oral anti-fungal drug available by prescription most frequently used to treat infections caused by the fungus Candida, more commonly known as yeast. Yeast infections most often occur in the vagina, mouth, throat, urinary tract, or esophagus, yet they may also inhabit the lungs and other organs, from which point they can spread to the surface of the body, appearing, for example, on the eye, skin, and nails.

In addition to infections caused by candida, fluconazole is also sometimes used to treat fungal meningitis, which is caused by the strain crytopcoccus.
Fluconazole may also be used as a preventative measure among those vulnerable to fungal infection, including patients who have human immunodeficiency virus (HIV), are undergoing chemotherapy or radiation, or are preparing for a bone marrow transplant.

In the family of azole antifungals, fluconazole operates by inhibiting an enzyme which controls the production of an essential component in the fungal cell membrane, resulting in the depletion of that component and hence the death of the fungal cell.

Fluconazole is available either in tablet form or as a powder-based suspension.

Fluconazole Side Effects

Approved by the FDA in 1990, fluconazole has been known to cause certain side effects which generally are mild but can be more serious, particularly in the presence of certain underlying conditions. Clinical studies have shown that patients with HIV are almost two times more likely to experience adverse side effects than those without HIV. Out of 4000 patients monitored during their use of the drug for periods of 7 days or more, 16% reported negative side effects, ranging in degree of severity.

Common side effects may include the following. If any persist or are severe, be sure to consult your doctor:

  • abdominal pain
  • indigestion
  • heartburn
  • nausea
  • diarrhea
  • headache
  • dizziness
  • distorted sense of taste
  • reduced levels of potassium (WebMD)


More serious side effects may include those list below. If you experience any of these symptoms, consult your doctor right away or seek emergency care:

  • seizure
  • severe dizziness or fainting
  • fast or irregular heartbeat
  • skin rash or itch, blistering or peeling
  • severe tiredness and/or fatigue
  • loss of appetite
  • difficulty swallowing
  • difficulty breathing
  • bruising or bleeding
  • dark urine
  • pale stools
  • swelling of face, throat, mouth, tongue, eyes, hands, feet, ankles, or legs
  • reduced white blood cell count
  • reduced platelet count


Severe allergic reactions are rare but may occur and require immediate attention. Those which have been identified to this point include angioedema, jaundice, hepatitis, abnormal heartbeat, and exfoliative skin disorders such as toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome. Be sure to tell your doctor of any existing allergies, especially if they have ever manifested in your use of other azole antifungal drugs.

Those with a personal or family history of heart, liver, or kidney disease should exercise particular caution. The use of fluconazole in the presence of these underlying conditions can increase the risk of heart and liver damage. Low levels of potassium or magnesium, as may accompany the use of diuretics, can also put one at greater risk of heart problems, including fast or irregular heartbeat. Severe sweating, diarrhea, and vomiting might signify such conditions and should be reported to a doctor before fluconazole is prescribed.

Like many other drugs, fluconazole can result in dizziness and/or a lack of alertness, which can increase if accompanied by alcohol or marijuana. If you experience any alteration in alertness, judgment, or reaction time, do not operate a car or other machinery until those capacities return to normal.

As any drug, fluconazole can have potentially fatal reactions with other drugs. Always confer thoroughly with your doctor and your pharmacist if taking any other medication. Patients with difficulty absorbing fructose or glucose/galactose, or who have a sucrase-isomaltase deficiency, should avoid taking the suspension form of this drug, as it contains sucrose.

Women who are pregnant should seriously consult with their doctors before taking this drug. According to a 2016 report by HealthDay News, fluconazole may slightly increase the risk of miscarriage (by a little over 0.1%).

Fluconazole Dosage

Fluconazole, which requires a prescription, comes either in tablet or powder-based suspension form. Both forms are usually administered by mouth once a day, with or without food. The suspension form may also be administered by injection.

The dosage and duration of administration depends upon each patient’s particular condition. Certain conditions may require a single dose of fluconazole. Others may require daily dosage over the course of several weeks. In the case of fungal meningitis, one may have to continue dosage for 10-12 weeks even after lab tests for cryptococcus return negative results.

Because differing conditions will warrant different prescriptions, be sure to follow your doctor’s instructions carefully. Read the directions on your prescription label, and be sure to ask you pharmacist if any remain unclear. You may be told to take a double-dose on the first day of treatment. Follow these instructions exactly as prescribed.

Fluconazole tablets come in the amounts of 50, 100, 150, and 200 mg. In this form, normal adult dosages usually range between 50-400 mg.

The powder-based suspension comes in the amounts of 10 ml or 40 ml. The injection form contains 2 ml.

If taking fluconazole in its suspension form, be sure to shake the bottle well before each use to ensure that the liquid has been mixed thoroughly.

Continue taking fluconazole as directed until told otherwise by your doctor. If you see your symptoms subsiding, consult with your doctor but do not end your treatment on your own. The medication needs to remain at a constant level in your system in order to eradicate the fungal infection. If you end treatment too early, the infection may return.

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