Fluconazole dosage
Fluconazole is the drug behind the famous "one pill" yeast-infection treatment, and that single dose is genuinely what the FDA label says: 150 mg once, by mouth. Everything else fluconazole treats — thrush, esophageal candidiasis, cryptococcal meningitis, transplant prophylaxis — uses a loading dose on day 1 followed by a lower daily dose, for weeks. The two regimens behave differently in one way that matters clinically: multiple-dose courses must be cut by creatinine clearance in kidney impairment, while the single 150 mg dose is explicitly exempt. We rate medications and publish label figures; we do not sell fluconazole or prescribe it.
This is reference, not a dosing instruction. Fluconazoleis prescription-only and the dose is individualized and titrated by a prescriber to your condition, response, kidney/liver function and other medicines. The figures below are the FDA label’s — do not start, change or stop a dose based on this page.
Approved for: Vaginal candidiasis; oropharyngeal and esophageal candidiasis; other serious systemic Candida infections including candidemia, disseminated candidiasis and pneumonia; cryptococcal meningitis (acute treatment and suppression of relapse in patients with AIDS); Candida urinary tract infections and peritonitis; and prevention of candidiasis in patients undergoing bone marrow transplantation who receive cytotoxic chemotherapy and/or radiation therapy.
Available as: 50 mg, 100 mg, 150 mg and 200 mg tablets; powder for oral suspension reconstituted to 10 mg/mL or 40 mg/mL. An intravenous solution exists for patients who cannot take oral therapy.
| Use | What the label says |
|---|---|
| Vaginal yeast infection (vaginal candidiasis) | "The recommended dosage of DIFLUCAN for vaginal candidiasis is 150 mg as a single oral dose." One 150 mg tablet, taken once, with or without food — absorption is rapid and almost complete, so meals do not matter. |
| Oropharyngeal candidiasis (thrush) | "200 mg on the first day, followed by 100 mg once daily." The label notes clinical evidence of thrush "generally resolves within several days, but treatment should be continued for at least 2 weeks to decrease the likelihood of relapse." |
| Esophageal candidiasis | "200 mg on the first day, followed by 100 mg once daily. Doses up to 400 mg/day may be used." Treat for a minimum of three weeks and for at least two weeks after symptoms resolve. |
| Cryptococcal meningitis | Acute treatment: "400 mg on the first day, followed by 200 mg once daily," typically continued 10 to 12 weeks after the cerebrospinal fluid becomes culture negative. Suppression of relapse in patients with AIDS: "200 mg once daily." |
| Prophylaxis in bone marrow transplant | "The recommended DIFLUCAN daily dosage for the prevention of candidiasis in patients undergoing bone marrow transplantation is 400 mg, once daily," started several days before the anticipated onset of neutropenia. |
| Children (weight-based) | Oropharyngeal or esophageal candidiasis in pediatric patients 6 months and older: "6 mg/kg on the first day, followed by 3 mg/kg once daily" (esophageal disease may need up to 12 mg/kg/day). Cryptococcal meningitis: 12 mg/kg on day 1, then 6 mg/kg once daily. Systemic Candida infections in patients 3 months and older: "A loading dose of 25-mg/kg on the first day (not to exceed 800 mg) followed by 12-mg/kg once daily (not to exceed 400 mg)." Neonates under 3 months: 25 mg/kg on day 1, then 12 mg/kg once daily at gestational age 30 weeks or more, or 9 mg/kg once daily below 30 weeks. |
Maximum dose
For the higher-dose adult indications the label tops out at 400 mg once daily — used for cryptococcal meningitis day 1, bone marrow transplant prophylaxis, and severe esophageal or systemic Candida infection, where "doses up to 400 mg/day may be used." The only 800 mg figure in the label is a pediatric day-1 loading-dose cap (25 mg/kg not to exceed 800 mg), not an adult maintenance dose. Chronic maternal doses of 400 to 800 mg/day appear in the label only as the exposures linked to birth defects.
Dose adjustments
This is where the single dose and the multi-day courses part ways. The label states plainly: "There is no need to adjust single dose therapy for vaginal candidiasis because of impaired renal function." For multiple-dose regimens, dosing follows creatinine clearance — patients with CrCl greater than 50 mL/min receive 100% of the recommended dose; patients at 50 mL/min or below who are not on dialysis receive 50% of the recommended dose; patients on regular hemodialysis receive "100% after each hemodialysis." An initial loading dose of 50 to 400 mg is still given first, then the maintenance dose is reduced. Fluconazole is cleared largely unchanged by the kidney, which is why the arithmetic matters on long courses and not on a one-time tablet.
Dosing safety — read before you rely on any number
QT prolongation: "Some azoles, including fluconazole, have been associated with prolongation of the QT interval on the electrocardiogram," via inhibition of the rectifier potassium channel current (Ikr); rare torsades de pointes has been reported, with hypokalemia and advanced cardiac failure raising risk. Co-administration with QT-prolonging CYP3A4 substrates — erythromycin, pimozide, quinidine — is contraindicated. Hepatotoxicity: "DIFLUCAN has been associated with rare cases of serious hepatic toxicity, including fatalities primarily in patients with serious underlying medical conditions"; monitor liver function and stop the drug if signs of liver injury appear. Interactions: fluconazole is "a moderate CYP2C9 and CYP3A4 inhibitor" and "a strong inhibitor of CYP2C19," so it raises levels of warfarin (prothrombin time may increase), phenytoin, cyclosporine, oral hypoglycemics (clinically significant hypoglycemia can be precipitated), short-acting benzodiazepines such as midazolam and triazolam (IV midazolam clearance fell 51%), and statins metabolized by CYP3A4 — with myopathy and rhabdomyolysis reported. Rifampin runs the other way and lowers fluconazole levels. Pregnancy: the label reports "a pattern of distinct congenital anomalies in infants exposed in utero to high dose maternal fluconazole (400 to 800 mg/day) during most or all of the first trimester," and separately that "epidemiological studies suggest a potential risk of spontaneous abortion and congenital abnormalities in infants whose mothers were treated with 150 mg of fluconazole as a single or repeated dose in the first trimester." So the single 150 mg dose is not simply declared safe in pregnancy — it carries a stated potential risk and is a prescriber judgment call; high-dose chronic use in the first trimester is the exposure the label attaches the distinct anomaly pattern to.
Bottom line
For an uncomplicated vaginal yeast infection the FDA-labeled dose is exactly one 150 mg tablet, taken once, food or no food — and it needs no adjustment for kidney impairment. Everything longer than that runs on a day-1 loading dose (usually double the maintenance dose) followed by a daily dose for weeks, and those courses must be halved when creatinine clearance falls to 50 mL/min or below. Before taking it, the two questions worth asking a pharmacist are what else you take (fluconazole is a strong CYP2C19 and moderate CYP3A4/2C9 inhibitor, so warfarin, statins, phenytoin and some sedatives are live concerns) and whether you might be pregnant — the label flags a potential risk even for the single 150 mg dose in the first trimester.
Frequently asked questions
How much fluconazole for a yeast infection?
The FDA label for Diflucan is unambiguous: "The recommended dosage of DIFLUCAN for vaginal candidiasis is 150 mg as a single oral dose." That is one 150 mg tablet, once. It can be taken with or without food, because oral absorption is rapid and almost complete. That single dose also requires no reduction for impaired kidney function.
Can you take a second dose of fluconazole?
The labeled regimen for vaginal candidiasis is one dose, and repeat or extended courses for recurrent or complicated infection are not part of the FDA-approved dosing in this label — they are prescriber decisions made off-label. This matters more than usual in pregnancy, because the label states that epidemiological studies suggest risk with 150 mg "as a single or repeated dose in the first trimester." Do not take a second dose on your own; ask the prescriber.
How long does fluconazole take to work?
The label does not give a symptom-relief timeline for vaginal candidiasis. The closest labeled statement is for thrush: "Clinical evidence of oropharyngeal candidiasis generally resolves within several days, but treatment should be continued for at least 2 weeks to decrease the likelihood of relapse." A single 150 mg dose keeps working after you swallow it — fluconazole has a long half-life, which is why one tablet can cover the infection. If symptoms have not improved after several days, that is a reason to be re-evaluated, not to redose.
Is fluconazole safe in pregnancy?
The label does not call it safe. It reports "a pattern of distinct congenital anomalies in infants exposed in utero to high dose maternal fluconazole (400 to 800 mg/day) during most or all of the first trimester" — and the label’s own position is that "use in pregnancy should be avoided except in patients with severe or potentially life-threatening fungal infections in whom fluconazole may be used if the anticipated benefit outweighs the possible risk to the fetus" — it does not list pregnancy as a contraindication. It separately states that epidemiological studies suggest a potential risk of spontaneous abortion and congenital abnormalities even with 150 mg as a single or repeated first-trimester dose. There are no adequate and well-controlled trials in pregnant women. Tell the prescriber if you are or might be pregnant; topical azole therapy is the usual alternative.
What are fluconazole's major drug interactions?
Fluconazole is "a moderate CYP2C9 and CYP3A4 inhibitor" and "a strong inhibitor of CYP2C19," so it raises blood levels of a lot of common drugs. The label specifically flags warfarin (prothrombin time may be increased), phenytoin, cyclosporine, oral hypoglycemic agents (clinically significant hypoglycemia can be precipitated), short-acting benzodiazepines including midazolam and triazolam, and statins metabolized by CYP3A4, where myopathy and rhabdomyolysis have been reported. Erythromycin, pimozide and quinidine are contraindicated because of combined QT risk. Rifampin cuts fluconazole levels rather than raising them.
Does fluconazole need a lower dose in kidney disease?
It depends on the regimen, and the label draws the line clearly. For multiple-dose courses, patients with creatinine clearance above 50 mL/min take "100% of recommended dose," patients at 50 mL/min or below who are not on dialysis take "50% of recommended dose," and hemodialysis patients get "100% after each hemodialysis" — after an initial loading dose. For the one-time treatment of vaginal candidiasis, the label states: "There is no need to adjust single dose therapy for vaginal candidiasis because of impaired renal function."
Sources
More guides for Fluconazole
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Doses are transcribed from the FDA-approved label and are general reference information, not medical advice or a personal dose. Only a prescriber can set or change your dose. If you think you took too much, contact Poison Control (1-800-222-1222) or 911.