Fluconazole: Uses, Side Effects, Dosages, and Interactions

Published August 16th, 2021 by Erik Rivera
Fact Checked by
Bridget Reed
Medically Reviewed:
Chris Riley

Fungal infections are common and can affect anyone. The different types of fungal infections range from uncomfortable vaginal yeast infections to potentially life-threatening fungal meningitis or invasive candidiasis. Fluconazole is a prescription medication that is commonly used to treat fungal infections.

What Is Fluconazole?

Fluconazole is a generic prescription medication that is commonly marketed under the brand name Diflucan. The medication was first approved by the FDA in 1993 and belongs to a class of antifungal medications called triazoles. 

There are two generations of triazoles, and fluconazole belongs to the first generation of this class of medications. The medication is available in the form of both a tablet and a liquid and is typically taken by mouth once per day with or without food.

What Is Fluconazole Used To Treat?

Fluconazole is an antifungal medication that is commonly used to treat a wide variety of fungal infections. While fluconazole is perhaps best known for its ability to treat yeast infections of the vagina, it is also commonly used to treat yeast infections of the mouth, esophagus, throat, abdomen, blood, lungs, and other organs. 

Additionally, fluconazole can also be used to prevent yeast infections. Patients who are undergoing chemotherapy or radiation therapy, particularly those who undergo these procedures prior to a bone marrow transplant, are considered to be at increased risk of developing a yeast infection due to their compromised immune systems during this time. Fluconazole can be given preventatively in order to help the patient avoid developing a yeast infection.

Fluconazole can also be used to treat fungal meningitis. While most people are familiar with bacterial meningitis, this infection of the membranes covering the brain and spine can also be caused by fungus.

What Causes Fungal Infections?

Anyone can develop a fungal infection, and the condition is extremely common. Common examples of fungal infections include athlete’s foot, ringworm, thrush, and vaginal yeast infection.

A fungal infection, also known as mycosis, can develop when a fungus that is not normally found in or on the body colonizes a specific body part and causes an infection. It can also develop when fungi that are normally present in the body start to grow out of control and cause an infection. 

Fungi thrive in damp, warm areas, so fungal infections are likely to develop in areas of the body that are warm and moist, such as the genitals, mouth, between the toes, around the groin, and inside the body. However, any part of the body may develop a fungal infection.

People are exposed to fungal spores every day. Fungi release spores into the air in order to reproduce and sometimes these spores land on the skin or are inhaled. Because of the mechanism by which people are typically exposed to fungal spores, fungal infections that affect the skin, nails, and lungs are the most common. 

Some of the most common types of fungal infections include:

  • Yeast infection
  • Jock itch
  • Athlete’s foot
  • Ringworm
  • Onychomycosis, a fungal infection of the nail

Fungal infections can be contagious, spreading from person to person. That is why athlete’s foot and jock itch can easily become such a pervasive problem among athletes, as shared surfaces like locker room floors and showers can easily transmit the fungus.

How Does Fluconazole Treat Fungal Infections?

Fluconazole works to treat fungal infections by killing the fungus that is causing the infection. Specifically, fluconazole creates holes in the cell membrane of the fungus, causing the contents of the fungus cell to leak out. As a result, the cell dies and the infection starts to improve, making symptoms diminish until they disappear.

Some people take fluconazole to prevent fungal infections. When used for the prevention of infections, fluconazole works by killing fungus when and if it begins to appear on or in the body.

How Long Does It Take For Fluconazole to Work?

Fluconazole works quickly to treat fungal infections. Depending on the type of fungal infection and the severity of the infection, some people may only need to take one dose of fluconazole in order to eliminate their infection. 

More commonly, fluconazole works in about a week to treat symptoms of vaginal yeast infection, balanitis, or oral thrush. 

People with more serious fungal infections, including fungal meningitis, may need to take fluconazole for two weeks or more before the medication fully eliminates the infection.

How Do I Know What Dose of Fluconazole to Take?

Fluconazole is available by prescription only, so your doctor will prescribe the appropriate dose and dosing instructions for you based on the type and severity of your infection. The medication is available in the form of a capsule and a liquid, and each formula can be taken with or without food.

Fluconazole capsules are available in strengths of 50 mg, 100 mg, 150 mg, and 200 mg, while the liquid form is available in two strengths: 50 mg per 5 milliliters (ml) and 200 mg per 5 ml. 

When using the liquid form of fluconazole, you should always use the measuring cup or spoon that is given to you with your medication so that you get the right amount of the medicine.

The amount of fluconazole that you take will vary depending on the type of infection you are experiencing. 

Common dosages are listed below:

  • Vaginal yeast infection or balanitis: 150 mg taken as a single dose (one time)
  • Persistent vaginal yeast infection: 150 mg taken once every 3 days for the first 3 doses, then once a week for 6 months
  • Yeast infections of the blood or other parts of the body: 200 mg to 800 mg taken once per day for several weeks
  • Oral thrush: 200 mg on the first day, then 100 mg every day for at least 2 weeks
  • Fungal meningitis: 400 mg on the first day, then 200 mg every day for 10 to 12 weeks
  • Prevention of fungal meningitis: 200 mg per day for as long as needed
  • Prevention of fungal infections in people with compromised immune systems: 50 mg to 400 mg per day until the immune system is no longer compromised

Are There Any Side Effects I Should Be Aware Of?

Fluconazole is a convenient way to treat fungal infections, particularly yeast infections that often require the use of messy creams. However, fluconazole is associated with a long list of potential side effects that deter some people from using the medication. Common side effects associated with fluconazole include:

  • Headache
  • Nausea
  • Vomiting
  • Diarrhea
  • Upset stomach
  • Dizziness
  • Change in ability to taste food

If you experience any of the above symptoms in a manner that is severe or lasts for an extended period of time, contact your doctor.

Fluconazole has the potential to cause serious side effects. Patients experiencing any of the following side effects should contact their immediately and seek emergency medical attention:

  • Extreme tiredness
  • Lack of energy
  • Pain in the upper right part of the stomach
  • Flu-like symptoms
  • Pale stools
  • Rash
  • Hives
  • Swelling of the face, tongue, eyes, feet, lower legs, throat, lips, hands, or ankles
  • Unusual bleeding or bruising
  • Loss of appetite
  • Yellowing of the eyes or skin
  • Dark urine
  • Seizures
  • Blistering or peeling skin
  • Itching
  • Difficulty breathing or swallowing

What Drug Interactions Are Associated With Fluconazole?

Fluconazole has a lengthy list of drug interactions that may make the medication unsafe for use in certain individuals. People who are allergic to fluconazole or any other antifungal medication, including the following, should alert their doctor or pharmacist prior to taking fluconazole:

  • Itraconazole
  • Ketoconazole
  • Posaconazole
  • Voriconazole

Individuals taking any of the following medications will likely not be able to use fluconazole safely:

  • Erythromycin
  • Pimozide
  • Quinidine
  • Terfenadine
  • Astemizole
  • Cisapride

The following medications are known to react with fluconazole and can increase your risk of experiencing side effects or make the medication less effective:

  • Amitriptyline
  • Amphotericin B
  • Blood thinners
  • Calcium channel blockers
  • Carbamazepine
  • Celecoxib
  • Statin medications
  • Cyclophosphamide
  • Cyclosporine
  • Diuretics
  • Fentanyl
  • Isoniazid
  • Losartan
  • Methadone
  • Midazolam
  • Nevirapine
  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Oral contraceptives
  • Oral medication for diabetes
  • Phenytoin
  • Prednisone
  • Rifabutin
  • Rifampin
  • Saquinavir
  • Sirolimus
  • Tacrolimus
  • Theophylline
  • Tofacitinib
  • Triazolam
  • Valproic acid
  • Vinblastine
  • Vincristine
  • Vitamin W
  • Voriconazole
  • Zidovudine

This may not be a complete list of drug interactions. Consult a healthcare provider for other possible interactions. 

Summary

Fluconazole is an antifungal medication commonly used for the treatment of fungal infections like yeast infections, fungal meningitis, athlete’s foot, and more. The medication is available by prescription only and comes in the form of a tablet or liquid. 

Side effects commonly associated with fluconazole include headache, nausea, diarrhea, upset stomach, dizziness, and a change in the ability to taste food.

Fluconazole is associated with a long list of drug interactions, so make sure to give your doctor a complete list of all medications, dietary supplements, and herbs you are currently using.

Sources:

Triazole antifungals: a review | Pub Med 

Fluconazole | U.S. National Library of Medicine 

Fluconazole: medicine to treat fungal infections including nail infections | National Health System 

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