Fluconazole

What is fluconazole?

Fluconazole belongs to a group of medicines referred to as triazole antifungals. It works by interfering with the formation of the cell wall and preventing or slowing the growth of pathogenic fungi or yeast.

This drug is available by prescription only.

What is fluconazole used to treat?

Fluconazole is approved by the US Food and Drug Administration (FDA) for the treatment of a variety of Candida fungal infections in the mouth (thrush), esophagus, genital region, lungs, and urinary tract and disseminated (systemic) candidal infections in adults and children. It is also indicated for use in treating cryptococcal meningitis.

Fluconazole is sometimes used as a preventative treatment for patients preparing for a bone marrow transplant. Some physicians may prescribe fluconazole off-label when treating certain infections caused by other fungi, such as coccidioidomycosis.

Dosage forms and strengths

Fluconazole is available in pill and powder forms (for making liquid suspensions). It also comes in an injectable form that is administered by a healthcare professional for the treatment of systemic fungal infections.

Your doctor will determine the appropriate form and strength of fluconazole for your particular medical condition. Dosing for children will be based on their weight.

Tablets (generic, Diflucan):

• 50mg

• 100mg

• 150mg

• 200mg

Injection (generic only):

• 200mg/100mL

• 400mg/200mL

Powder for suspension (generic, Diflucan):

• 10mg/mL

• 40mg/mL

How do you take fluconazole?

Before beginning fluconazole and every time you get a refill, you should read the patient information provided by the pharmacist as well as the drug manufacturer. If you have questions, contact your pharmacist or doctor.

You can take fluconazole with or without food. It's best to try and take your doses at about the same time each day.

The liquid suspension form of the drug should be shaken well before measuring out your dose. Always use the measuring device provided by your pharmacist and not a household spoon. Once reconstituted, the liquid suspension may be stored at room temperature (away from heat, direct light, and moisture) or in the refrigerator for up to 14 days.

Depending upon the medical condition for which you're being treated, you might take one dose only, or you may need to repeat your dose weekly for a longer period.

Seeing results

Once fluconazole enters the body, it begins working quickly. The oral forms of the drug reach peak concentrations in the blood between one and two hours, and the injectable type performs similarly. While the rate of action can vary depending on personal characteristics, you may start to see improvements within a few days.

You shouldn't discontinue the drug until you've finished the full course of medication prescribed to you, even if you feel well. If you stop too soon, the infection may return.

Who should not take fluconazole?

If you've ever had an allergic reaction to fluconazole or a similar medication, you should not take the drug again.

You may need to use caution when taking fluconazole if you are a reproductive-aged female or you have any of the following conditions:

• Heart rhythm abnormalities, such as prolonged QT (or family history), bradycardia, or other arrhythmias

• Cardiovascular disease or a recent heart attack

• Congestive heart failure

• Kidney disease

• Liver disease

• Pregnancy

• Genetic conditions, such as fructose intolerance, glucose or galactose malabsorption, and sucrase or isomaltase insufficiency (when taking the liquid form)

• Electrolyte abnormalities like low sodium or calcium in the blood

Potential side effects of fluconazole

Common side effects

The common side effects associated with fluconazole include:

• Stomach pain

• Headache

• Diarrhea

• Dizziness

• Rash

• Changes in taste

If you experience any of these common side effects, speak with your doctor or pharmacist.

Severe side effects

Fluconazole can cause elevated liver enzymes, low white blood cell or platelet counts, low potassium levels, and high lipid levels. It can also cause gallbladder stasis and hepatitis.

Contact your doctor if you experience any of the following adverse effects:

• Nausea or vomiting

• Loss of appetite

• Weight loss

• Upper abdominal pain

• Unusual fatigue

• Muscle weakness

• Unusual rash, hives, or itching

• Abnormal bruising, bleeding, or swelling

Seek immediate medical attention if you experience any of the following symptoms:

• Hallucinations

• Paranoia

• Serious allergic reaction

• Severe rash or peeling skin

• Dark urine

• Vomiting

• Jaundice

If you think you're having an allergic reaction to fluconazole, or if you have any severe side effects such as fainting, difficulty breathing, abnormal heartbeat, dark urine, severe abdominal pain, or vomiting that won't stop, you should visit your local emergency department or call 911.

Overdose

If you suspect you may have overdosed on fluconazole, call 911 or the National Poison Control helpline at 1-800-222-1222, depending on the severity of your symptoms.

Symptoms of a possible overdose include any of the following:

• Mood or mental changes

• Confusion

• Hallucinations or paranoia

• Abnormal bruising or purple rash

• Difficulty breathing

• Loss of consciousness

Allergy information

Symptoms of an allergic reaction to fluconazole include:

• Hives/blisters on the skin, itching, or rash with skin peeling

• Vomiting

• Difficulty breathing or wheezing

• Elevated heart rate

• Swelling in your throat, tongue, or anywhere on the face

• Loss of consciousness

If you develop allergic symptoms after taking fluconazole, you should seek immediate medical attention either by visiting the closest emergency department or dialing 911, depending on the severity of your symptoms.

Long-term use of fluconazole

The duration of treatment with fluconazole depends on the condition being treated and its severity. Your doctor may recommend taking fluconazole for weeks or even months. Research suggests that the risk of unwanted side effects increases with long-term use. In one 2018 study, more than half of the 124 participants experienced adverse effects while taking the drug longer than 28 days.

Fluconazole and pregnancy

According to the US FDA, fluconazole falls into different categories depending on the dose and indications for treatment. When the drug is used for treating vaginal candidiasis, it is designated a pregnancy category C medication. Category C means adverse effects were seen in animal studies, but there is insufficient data from human studies to determine the risks in pregnancy. 

Fluconazole is classified as a category D drug (as of 2017) when it is used for other indications during pregnancy. Drugs designated pregnancy category D have shown clear evidence of harm to the fetus.

There are cases in both categories for which the benefits of taking the drug outweigh the potential risks. If you're pregnant or thinking about becoming pregnant and need to take fluconazole, your doctor will review the potential risks and benefits to determine what is best for you. The decision will be based on many factors, including the condition being treated, other medications you are taking, any other medical conditions you have, and how far along you are in your pregnancy.

Fluconazole and breastfeeding

Fluconazole is excreted poorly into breast milk, appearing in lower concentrations than the recommended neonatal dosage. In fact, fluconazole is frequently prescribed to nursing mothers to aid in the treatment of recurrent breast candidiasis.

Missed doses

If you miss a dose of fluconazole, and it’s more than halfway to the time of your next dose, simply wait and take your next dose at its usual time. Otherwise, take your missed dose right away, then take your next dose at the regularly scheduled time. Never double your dose to make up for a missed one, as doing so could result in an accidental overdose.

You can always call your pharmacist or doctor for advice if you're not sure what to do after missing a dose.

Drug interactions

You can reduce your risk of drug interactions by informing your doctor of all medications, herbs, vitamins, and supplements you take regularly or occasionally.

Drugs known to interact with fluconazole include the following:

• Antiarrhythmics like amiodarone (Cordarone, Pacerone)

• Antibiotics, including azithromycin (Zithromax), erythromycin, rifampin, and rifabutin (Mycobutin)

• Anti-seizure medicines like carbamazepine (Tegretol) and phenytoin (Dilantin)

• Antiviral medications, such as zidovudine (Retrovir) and saquinavir (Invirase)

• Benzodiazepines, including lorazepam (Valium) and alprazolam (Xanax)

• Blood thinners, such as warfarin (Coumadin) and clopidogrel (Plavix)

• Calcium channel blockers like nifedipine (Procardia), amlodipine (Norvasc), and verapamil (Calan SR)

• Cholesterol-lowering drugs, such as atorvastatin (Lipitor), lovastatin (Mevacor), and simvastatin (Zocor)

• Diabetes medicines like glyburide (Glynase) and glipizide

• Immune-modulating drugs, such as cyclosporine (Gengraf, Neoral), ibrutinib (Imbruvica), and tacrolimus (Astagraf XL, Prograf)

• Non-steroidal anti-inflammatory medications, including ibuprofen (Motrin, Advil), naproxen (Naprosyn), and meloxicam (Mobic)

• Pain medications, such as meperidine (Demerol), oxycodone (Oxycontin), and fentanyl (Actiq, Duragesic)

• Pimozide 

• Vitamin A supplements

This is not a complete list of drug interactions. Review all medications you take regularly or occasionally with your doctor before taking fluconazole.

Can I drink alcohol while taking fluconazole?

While there is no known direct harm if a person drinks alcohol while taking fluconazole, both alcohol and fluconazole have the potential to cause damage to the liver. If you have liver disease or an increased risk of liver issues, it's best to avoid or use caution when drinking alcohol while taking fluconazole.

What to discuss with your doctor before starting fluconazole

Fluconazole is available by prescription only, so you’ll need to meet with your doctor before you start taking it. At your appointment, you should discuss all of the following topics that apply to you:

• Any drug allergies or previous reactions to medicines

• Your medications (both prescription and over-the-counter) and all herbal and nutritional supplements you take regularly or occasionally

• Your medical history and other health conditions, particularly immune-related conditions, abnormal heart rhythms, liver or kidney disease, lactose intolerance, and any hereditary condition related to glucose or fructose absorption

• Your alcohol use and history

• Whether you're breastfeeding, thinking about becoming pregnant soon, or currently pregnant (especially in your first trimester)

Stopping fluconazole

Continue your prescribed course of fluconazole, even if you feel your condition has resolved. If you experience unwanted side effects while taking the medication and wish to discontinue treatment, ask your doctor about alternative therapies.

If you’re on long-term therapy with fluconazole and prednisone, your doctor may need to monitor for adrenal insufficiency (a condition affecting your body’s hormone production processes) when you stop taking fluconazole.

Drug approval history

• 1990: Fluconazole earned US FDA approval

Tips for taking fluconazole

• Store your medication at room temperature and away from direct light, heat, and moisture.

• If you're taking the liquid suspension form of fluconazole, store it at room temperature or in the refrigerator, but never in the freezer.

• Tell your prescriber if you are pregnant, breastfeeding, or trying to conceive.

• If you have any questions, don't hesitate to contact your pharmacist or doctor. They want you to take fluconazole correctly so you can get better as quickly as possible.

Frequently asked questions

Do you take fluconazole every three days?

Your doctor will determine the appropriate dose and dosing schedule for you based on your condition. Patients with a vaginal yeast infection, for example, may only need one dose.

Is it better to take fluconazole at night?

You can take fluconazole at any time of the day but try to take it around the same time each day.

Is fluconazole an antibiotic?

Fluconazole is an antifungal medication, not an antibiotic, and it is not an effective treatment for infections caused by bacteria.