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Drug Info

How long does fluconazole take to work?

This medication is typically effective in one to three days, but it can take longer depending on certain factors
Heidi Borst
By | Nov. 18, 2024 Medically reviewed by Karen Berger, Pharm.D.
alarm clock next to a pill - how long does it take for fluconazole to work

Key takeaways

  • Fluconazole is an antifungal medication effective against various fungal infections, including candidiasis and cryptococcal meningitis.

  • The medication generally takes 24 to 72 hours to show effects. However, it can take longer depending on your infection and your health status.

  • Fluconazole dosage varies based on the type and severity of the infection. A single 150 mg dose is recommended for vaginal yeast infections, while systemic infections usually require higher doses and longer duration of treatment.

  • Before taking fluconazole, tell your healthcare provider about all of your medical conditions. Also, be sure your provider knows about all the medications you take, including prescription and OTC drugs, vitamins, and supplements.

In this article:

Fluconazole, brand name Diflucan, is an antifungal medication that is FDA approved for treating various fungal infections, including yeast infections and certain types of meningitis. It may also be prescribed preventively in patients receiving chemotherapy or radiation or before a bone marrow transplant. Fluconazole works by inhibiting the growth of fungi and begins to show effects within 24 to 72 hours of administration. However, it may take one to two weeks for the medication to eliminate an infection.

How long does it take for fluconazole to work?

Fluconazole typically starts working within 24 to 48 hours for simple infections like a vaginal yeast infection, says Michael Lahey, MD, an emergency medicine physician based in Vermont. “In more severe cases, like systemic mycoses (fungal infections that invade deep organs), it may take days to weeks for the onset of symptom relief,” says Dr. Lahey.

Fluconazole works by stopping the growth of Candida and Cryptococcus fungus, such as occurs with the following infections when caused by susceptible fungi:

  • Candidiasis, including oral thrush, esophageal candidiasis, urinary tract infections, vaginal yeast infections, pneumonia, and peritonitis
  • Cryptococcal meningitis, an infection typically seen in immunocompromised individuals, such as those with HIV/AIDS

It can also prevent fungal infections in immunocompromised patients undergoing chemotherapy, radiation, or organ or bone marrow transplants.

While patients may notice symptom relief in a few days, complete resolution of the infection may take longer. You’ll know it’s working when your symptoms begin to improve, such as reduced itching or discharge with a vaginal yeast infection or improvement in white patches, soreness, and redness with oral thrush.

RELATED: How to get rid of a yeast infection in 24 hours

What can affect how long fluconazole takes to work?

Dr. Lahey says several factors can influence the onset of fluconazole’s effects. They include:

  • The severity of the infection: Systemic infections or very acute ones are slow to show a response to the treatment.
  • Type of infection: Skin infections may be cured earlier than internal ones or other serious infections. While you may think taking the highest dose is the best way to clear an infection the fastest, the dosage you’re prescribed depends on the infection being treated. For example, treatment for a vaginal yeast infection typically requires a single 150 mg dose, while oral thrush generally requires at least 14 days of treatment. Systemic infections may require higher doses and prolonged courses of the medication. Your provider will determine the best dosage to treat your infection the fastest while minimizing medication side effects.
  • Health status: For example, immunocompromised individuals require a longer duration of treatment before symptoms are alleviated. Additionally, the drug has a longer half-life in patients with chronic kidney disease (CKD) because kidney function decreases the body’s ability to eliminate the drug, which is mainly excreted through the kidneys. That means the drug clears more slowly, and a dose reduction may be required.

While there’s no way to speed up the effectiveness of fluconazole, Dr. Lahey says you’ll get the best results by following your prescribing healthcare provider’s instructions and taking the medication exactly as prescribed.

RELATED: What causes yeast infection?

What is the standard fluconazole dosage?

While a common dosage is 150 mg, the exact dose of fluconazole you need depends on the type and severity of your fungal infection. The prescribing information provides the following adult dosage guidelines:

  • Vaginal candidiasis:150 mg as a single dose.
  • Oropharyngeal candidiasis: 200 mg on the first day, followed by 100 mg once daily for at least two weeks to avoid relapse.
  • Esophageal candidiasis: 200 mg on the first day, followed by 100 mg once daily for at least three weeks. Doses up to 400 mg/day may be used.
  • Systemic Candida infections: While dosage guidelines have not been established for blood and organ infections, doses of up to 400 mg daily have been prescribed.
  • Candida urinary tract infections and peritonitis: 50 to 200 mg daily.
  • Cryptococcal meningitis: 400 mg on the first day, then 200 to 400 mg once daily for 10 to 12 weeks after the cerebrospinal fluid culture is negative.
  • Prevention in patients undergoing bone marrow transplantation: 400 mg once daily, with duration determined by a healthcare professional.

RELATED: Can men get yeast infections?

Who should avoid taking fluconazole?

Certain individuals should avoid fluconazole, including those allergic to the drug, people who take certain medicines, or women in the first trimester of pregnancy. Additionally, those with the following medical conditions should seek medical advice from a healthcare provider before taking the medication:

  • Irregular heart rhythm
  • Kidney or liver disease
  • Low potassium levels in the blood
  • Previous allergic reaction to fluconazole or other azole antifungals
  • Pregnant or breastfeeding
  • QT prolongation

Common side effects of fluconazole include:

  • Headache
  • Dizziness
  • Diarrhea
  • Stomach pain
  • Heartburn
  • Changes in taste

The following rare but serious side effects warrant immediate medical attention:

  • Nausea and vomiting
  • Extreme fatigue
  • Unusual bruising or bleeding
  • Decreased energy
  • Loss of appetite
  • Upper right abdominal pain
  • Jaundice, including yellowing of the eyes and skin
  • Liver problems
  • Dark urine
  • Pale stool
  • Flu-like symptoms
  • Seizures
  • Skin rash, hives, itching, or blistering, peeling skin
  • Swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
  • Difficulty swallowing or breathing

Additionally, fluconazole has drug interactions with certain medications, such as:

Because different drug interactions occur in different ways, talk to your healthcare provider about fluconazole drug interactions and how they may affect you. Some drug combinations must be avoided, while others may be managed with a dosage adjustment. Before taking fluconazole, tell your healthcare provider about all the medications you take, including prescription and OTC medicines, vitamins, and supplements. This will help your healthcare provider determine if fluconazole is safe for you.

The bottom line

Fluconazole usually begins to work within 24 to 72 hours, but various factors, such as type of infection and individual health, can influence this timeframe. For effective treatment, it’s essential to complete fluconazole treatment as directed by your healthcare provider.

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