Fluconazole dosage, forms, and strengths
Key takeaways
Fluconazole is a generic antifungal medication used to treat various fungal infections. It comes in an oral tablet, oral suspension, and intravenous (IV) injection.
The fluconazole dosage depends on the type of infection it’s prescribed for. For children, the dosage is based on the condition being treated and the child’s body weight.
Ask your healthcare provider how long you should take fluconazole. Some conditions only require a single dose, while others require long-term treatment.
Fluconazole (Diflucan) is a medication used to treat fungal infections that affect the skin, digestive system, blood, nails, brain, urinary tract, and genitals. It belongs to a drug class called triazole antifungals
. While it is a very common and useful medication, fluconazole interacts with many medications. This article will review important details about fluconazole dosages, drug interactions, and how to use it safely.
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Fluconazole dosage chart |
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|---|---|---|---|
| Indication | Starting dosage | Standard dosage | Maximum dosage |
| Oropharyngeal candidiasis | 200 mg on the first day | 100 mg daily for at least 2 weeks | 400 mg daily |
| Esophageal candidiasis | 200 mg on the first day | 100-400 mg daily for at least 3 weeks | 400 mg daily |
| Candidemia | Determined by your healthcare provider | Determined by your healthcare provider | 400 mg daily |
| Cryptococcal meningitis | 400 on the first day | 200-400 mg daily | Determined by your healthcare provider |
| Prevention of candidiasis in patients undergoing bone marrow transplant | 400 mg daily | 400 mg daily | 400 mg daily |
| Coccidioidomycosis (valley fever) | 400-1,200 mg daily | 400-1,200 mg daily | Determined by your healthcare provider |
| Candidal pyelonephritis | 200-400 mg daily | 200-400 mg daily for 2 weeks | 400 mg daily |
| Candidal cystitis | 200-400 mg daily | 200-400 mg daily for 2 weeks | 400 mg daily |
| Toenail onychomycosis | 150-450 mg once per week | 150-450 mg once per week for 6-12 months | 450 mg weekly |
| Fingernail onychomycosis | 150-450 mg once per week | 150-450 mg once per week for 3-6 months | 450 mg weekly |
| Vaginal candidiasis | 150 mg by mouth as a single dose | 150 mg by mouth as a single dose | Determined by your healthcare professional |
Fluconazole forms and strengths
Fluconazole is available as a tablet or as a liquid suspension under the brand name Diflucan or in the generic form. It is also available as an intravenous injection.
Tablets: 50 mg, 100 mg, 150 mg, 200 mg
Suspension: 10 mg/ mL, 40 mg/ mL
Injection: 2 mg/mL
Fluconazole dosage for adults
Fluconazole is commonly used to treat candida infections, but it’s also effective against other types of molds and fungi, including cryptococcus neoformans, Blastomyces dermatitidis, coccidioides immitis, Histoplasma capsulatum, Malassezia furfur, prototheca species, dematiaceous molds, and dermatophytes. Below are some common infections that fluconazole may be prescribed to treat:
Fluconazole dosage for esophageal and oropharyngeal candidiasis
Fluconazole is commonly used to treat yeast infections of the mouth or throat (thrush). The typical dose is 200 mg on day one, followed by 100 to 400 mg depending on whether the infection is in the mouth (oral), just behind the mouth (oropharyngeal), or lower in the esophagus (esophageal). Yeast infections of the throat typically resolve within several days, but treatment should be continued for two to three weeks.
Fluconazole dosage for candidemia
Candidemia is a type of systemic candida infection in which candida is present in the blood. It is the most common fungal bloodstream infection in hospitalized patients. It is diagnosed by performing a blood culture, which will also determine how effective fluconazole will be against the infection. Based on the severity of the infection and the results from the blood culture, a different antifungal such as an echinocandin may be needed. There isn’t a standard fluconazole dosage for candidemia. A healthcare provider will prescribe a dosage based on several factors, including the severity of the infection, your age, and your other medical conditions.
Fluconazole dosage for cryptococcal meningitis
Cryptococcal meningitis is diagnosed by obtaining a culture of the cerebral spinal fluid (CSF) via a lumbar puncture. A healthcare provider will determine the best treatment based on several factors, such as if you’re pregnant or have HIV. Treatment options may include amphotericin B flucytosine, and fluconazole. The recommended dosage of fluconazole is 400 mg on the first day, followed by 200-400 mg daily for at least 10-12 weeks after the CSF culture is negative.
Fluconazole dosage for prevention of candidiasis in BMT patients
The recommended fluconazole dosage for preventing candidiasis in patients undergoing bone marrow transplantation is 400 mg daily. In patients who are likely to have severe neutropenia (neutrophils fewer than 500 per cubic millimeter), fluconazole therapy should begin several days before the onset of neutropenia and continued for one week after the neutrophil count returns to 1,000 cells per cubic mm or higher.
Fluconazole dosage for urinary tract infections
For symptomatic urinary tract candida infections, fluconazole doses ranging from 200 to 400 mg daily for two weeks (depending on the location within the urinary tract, and the presence of complicating factors) have been shown to be effective.
Fluconazole dosage for vaginal candidiasis
Vaginal candidiasis (vaginal yeast infection) is one of the most common uses for fluconazole. In patients with uncomplicated disease (neither pregnant, immunocompromised, nor recurring vaginal candidiasis), a one-day treatment is sufficient. Patients with complicated diseases may require longer therapy. Finally, pregnant patients should not use oral fluconazole due to its potential for harm to the fetus.
Fluconazole dosage for coccidioidomycosis
Coccidioidomycosis, also known as valley fever, is caused by the coccidioides fungus. Infection usually begins in the lungs by inhaling wind-borne spores. The disease may be mild or severe, even life-threatening, if the infection spreads to the central nervous system. Some infections may be mild and resolve without any therapy. For more complicated infections, fluconazole is generally the treatment of choice. The recommended dosage is 400-1,200 mg daily. The duration of treatment is based on the resolution of symptoms and the location of the infection.
Fluconazole dosage for nail onychomycosis
Candida infections of the toenail or fingernail involve discoloration, thickening, and separation of the nails from the nail bed. They can be treated with oral fluconazole (although many antifungal treatment options exist). The fluconazole dose is 150 to 450 mg taken once weekly. The duration of therapy is three to six months for fingernail infections and six to 12 months for toenail infections.
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Fluconazole dosage for children
A general guideline for converting adult dosages into pediatric dosages is listed below:
| Pediatric patients | Adult patients |
| 3 mg/kg* | 100 mg |
| 6 mg/kg | 200 mg |
| 12 mg/kg | 400 mg |
* 1 kg is equal to 2.2 lbs.
The fluconazole dose for pediatric patients should not exceed 600 mg per day.
Fluconazole dosage by weight/age |
||
|---|---|---|
| Indication | Recommended dosage | Max dosage |
| Oropharyngeal candidiasis | 6 mg/kg on first day, then 3 mg/kg once daily for at least 2 weeks | Determined by your healthcare provider |
| Esophageal candidiasis | 6 mg/kg on first day, then 3 mg/kg once daily for at least 3 weeks total duration and at least 2 weeks following resolution of symptoms | 12 mg/kg per day or 600 mg/day, whichever is less |
| Systemic Candida infections | 6–12 mg/kg per day for at least 2 weeks after first negative culture and resolution of symptoms | 12 mg/kg per day or 600 mg/day, whichever is less |
| Cryptococcal meningitis | 12 mg/kg on the first day, then 6-12 mg/kg daily for 10-12 weeks after negative culture returns | 12 mg/kg per day or 600 mg/day, whichever is less |
Fluconazole dosage restrictions
You should not take Diflucan (fluconazole) if you have had an allergic reaction (rash, hives, swelling of the face and throat) to its active ingredient or any component of Diflucan tablets or suspension in the past.
Diflucan should be administered with caution to patients with liver dysfunction. There have been rare reports of serious liver toxicity in patients taking Diflucan, primarily in patients with serious underlying medical conditions. In most cases, liver injury from Diflucan is reversed once Diflucan therapy is stopped. Diflucan should be discontinued if clinical signs and symptoms consistent with liver disease develop after beginning treatment.
Exfoliative skin disorders during treatment with Diflucan have been reported. Patients with deep-seated fungal infections who develop rashes during treatment should be monitored closely. Diflucan should be discontinued if lesions progress.
Diflucan should not be used in pregnant women due to the potential for fetal harm. There have been case reports of congenital anomalies–also known as birth defects– in infants exposed to high doses of fluconazole during most or all of the first trimester. Effective birth control should be used in women of childbearing age who are being treated with Diflucan 400 to 800 mg/day. Birth control should be taken during treatment and for approximately one week after the final dose.
Patients with a history of heart disease or arrhythmia, including congenital long QT syndrome, QT prolongation, torsades de pointes, ventricular arrhythmias, slow heart rate (bradycardia), recent heart attack (myocardial infarction), congestive heart failure, or other heart diseases should use caution while taking fluconazole. Fluconazole is known to increase the QT interval (a measure of time between stages of heart contraction), which can worsen arrhythmias or other cardiovascular conditions.
Fluconazole should be taken with caution in older patients or patients with kidney dysfunction (low creatinine clearance). Fluconazole is broken down in the body primarily by the kidneys. People with kidney problems may break down fluconazole more slowly compared to those who don’t. This can cause fluconazole to build up in the body, which increases the risk of adverse effects. Because older adults are more likely to have kidney problems, healthcare professionals may prescribe a lower dosage of fluconazole if you’re 65 years or older.
Fluconazole dosage for pets
Fluconazole is used to treat yeast infections in cats, dogs, and other small mammals. While fluconazole does not have FDA approval for this use, it is effective and commonly prescribed for pets with yeast infections of the skin, nail beds, urinary tract, or other organs. One study found a starting dose of 10 mg/kg twice daily for dogs, or 50-100 mg per day in cats, was effective to treat fungal infections. Although, doses will likely be individualized by a healthcare provider.
How to take fluconazole
Read and follow the patient instructions that come with this medicine. Talk to your healthcare provider or pharmacist if you have any questions.
Fluconazole tablets and oral suspension can be taken with or without food.
Tablets may be cut or crushed if needed.
Shake the oral suspension well before using. Store reconstituted suspension between 41 and 86 degrees Fahrenheit and discard unused portion after two weeks.
Use the dosing syringe provided or use a medicine dose-measuring device (not a kitchen spoon).
Store fluconazole at room temperature away from moisture and heat. Do not freeze.
Use fluconazole for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. Fluconazole will not treat a viral infection such as the flu or a common cold.
Fluconazole dosage FAQs
How long does it take fluconazole to work?
Oral fluconazole reaches its peak concentration in the bloodstream about one to two hours after being taken by mouth. The time it takes fluconazole to alleviate symptoms depends on the dosing regimen and the type of infection being treated.
For vaginal yeast infections, symptoms may start to improve within 24 hours. But it can still take a few days for the infection to fully clear. Contact your healthcare provider if you don’t feel better within 3 days.
For oral infections, symptoms should improve within a week of starting fluconazole treatment.
How long does fluconazole stay in your system?
Fluconazole has a half-life of about 30 hours. Half-life is the time it takes for half of a drug’s concentration to clear from the body. In general, the majority of a drug will be eliminated from the body after 4 to 5 half-lives. This means fluconazole should be cleared from the body after about six days.
What happens if I miss a dose of fluconazole?
In the event of a missed dose, take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
How long can you take fluconazole?
The duration of fluconazole therapy depends on the type of infection being treated. Some infections, such as vaginal candidiasis, may only require a one-time dose. On the other end of the spectrum, coccidioidal meningitis, may require long-term treatment. For urinary tract infections, the duration of therapy is typically two weeks. A healthcare provider will monitor symptoms and lab results to determine when the infection is cured.
What interacts with fluconazole?
Many drugs interact with fluconazole, and the dose of many drugs will be adjusted to account for this. It is very important to share a list of current medications with a healthcare provider while taking any antifungal drug.
What happens when you mix fluconazole and alcohol?
It is safe to eat and drink normally while taking fluconazole. There are no known interactions between alcohol and fluconazole. However, since both fluconazole and alcohol can have negative effects on the liver, it is advisable for patients with liver impairment (i.e. jaundice, hepatitis) to avoid alcohol, especially while taking fluconazole. Another important consideration is that excessive alcohol use can weaken the immune system and worsen candida infections, potentially working against the effects of fluconazole.
Is it safe to take fluconazole during pregnancy?
In most cases, it is not safe to take fluconazole during pregnancy, especially during the first trimester.
Fluconazole may be used while breastfeeding, as low levels of the drug pass into breast milk. However, it’s best to check with a healthcare provider to see if it’s safe for you to breastfeed your baby while taking fluconazole.
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