ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Triazole antifungal Pregnancy: Single dose (150 mg) relatively safe. Prolonged high doses associated with fetal anomalies — avoid in first trimester.

Fluconazole

Brand names: Diflucan

Adult dose

Dose: Oropharyngeal candidiasis: 50–100 mg daily for 7–14 days; Systemic/invasive: 400–800 mg loading then 200–400 mg daily; Vaginal candidiasis: 150 mg single dose
Route: Oral or IV
Frequency: Once daily
Max: 800 mg/day (Cryptococcal meningitis)
Vaginal candidiasis: 150 mg single oral dose. Oropharyngeal: 50 mg/day for 7–14 days. Cryptococcal meningitis (induction): 400–800 mg/day after amphotericin. Candidaemia: 800 mg loading then 400 mg daily.

Paediatric dose

Dose: 3 mg/kg
Route: Oral or IV
Frequency: Once daily
Max: 12 mg/kg/day (max 800 mg/day)
Concentration: 2 mg/ml
Neonatal candidiasis: 6–12 mg/kg every 72 hours (premature). Oropharyngeal: 3 mg/kg once daily. Systemic/invasive: 6–12 mg/kg once daily. Maximum dose depends on indication.

Dose adjustments

Renal

Halve dose (or double interval) if eGFR <50 for maintenance; no adjustment for single dose.

Hepatic

Use with caution in hepatic impairment; monitor LFTs.

Paediatric weight-based calculator

Neonatal candidiasis: 6–12 mg/kg every 72 hours (premature). Oropharyngeal: 3 mg/kg once daily. Systemic/invasive: 6–12 mg/kg once daily. Maximum dose depends on indication.

Clinical pearls

  • Inactive against Aspergillus — use voriconazole or isavuconazole for aspergillosis
  • Candida krusei and some C. glabrata strains intrinsically resistant
  • Monitor LFTs and drug interactions (major CYP2C9/3A4 inhibitor)
  • Single 150 mg dose for vaginal candidiasis — highly effective and convenient
  • Available as IV and oral (same bioavailability — can switch freely)

Contraindications

  • Concomitant use with terfenadine, cisapride, pimozide, quinidine, astemizole (QT prolongation risk)

Side effects

  • Nausea and abdominal discomfort
  • Headache
  • Elevated liver enzymes (hepatotoxicity — rare)
  • Rash (discontinue if severe — SJS risk in HIV patients)
  • QT prolongation

Interactions

  • Warfarin — major increase in INR (reduce warfarin dose)
  • Phenytoin — increases phenytoin levels
  • Statins (simvastatin, atorvastatin) — increased myopathy risk
  • Oral hypoglycaemics (sulphonylureas) — increased hypoglycaemia
  • Ciclosporin — increased levels
  • Rifampicin — reduces fluconazole levels

Monitoring

  • LFTs (prolonged use)
  • Drug interactions
  • Clinical response (culture if not responding)

Reference: BNFc; BNF; IDSA Candidiasis Guidelines 2016; PHE guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Drugs
Pathways