Antifungal (Azole)
Pregnancy: Contraindicated (single 150 mg dose — teratogenicity risk in first trimester at high doses; MHRA 2018)
Fluconazole
Brand names: Diflucan
Adult dose
Dose: Vaginal candidiasis: 150 mg single dose; Oropharyngeal candidiasis: 50–100 mg daily for 7–14 days; Invasive candidiasis: 400 mg loading then 200–400 mg daily
Route: Oral / IV
Frequency: Once daily (or single dose)
Max: 800 mg/day (invasive infection under specialist care)
IV and oral doses are equivalent (100% bioavailability). IV is reserved for those who cannot take oral. Cryptococcal meningitis: 400–800 mg once daily (with flucytosine induction phase).
Paediatric dose
Dose: 3–12 mg/kg
Route: Oral / IV
Frequency: Once daily
Max: 400 mg/day
Oropharyngeal candidiasis: 3 mg/kg on day 1 then 3 mg/kg daily. Invasive candidiasis: 6–12 mg/kg daily under specialist guidance.
Dose adjustments
Renal
Reduce dose by 50% if eGFR <50 mL/min (single doses do not require adjustment).
Hepatic
Use with caution in hepatic impairment — rare hepatotoxicity reported.
Paediatric weight-based calculator
Oropharyngeal candidiasis: 3 mg/kg on day 1 then 3 mg/kg daily. Invasive candidiasis: 6–12 mg/kg daily under specialist guidance.
Clinical pearls
- Warfarin interaction is clinically significant — check INR within 3–5 days of starting fluconazole in anticoagulated patients
- High oral bioavailability means IV is rarely needed — prefer oral unless genuinely not tolerated
- Azole resistance in Candida glabrata increasingly reported — send cultures in recurrent/treatment-resistant cases
Contraindications
- QT prolongation risk (concomitant QT-prolonging drugs)
- Coadministration with terfenadine, cisapride, astemizole, pimozide (risk of life-threatening arrhythmia)
Side effects
- Nausea
- Abdominal pain
- Headache
- Rash (Stevens-Johnson in immunocompromised)
- Elevated LFTs
- QT prolongation
Interactions
- Warfarin (significantly increases INR — monitor closely)
- Ciclosporin (increases levels)
- Tacrolimus (increases levels)
- Midazolam (increases sedation)
- Statins: simvastatin/atorvastatin (increases myopathy risk — suspend statin)
- Sulfonylureas (hypoglycaemia)
- Phenytoin (increased phenytoin levels)
Monitoring
- LFTs (prolonged use)
- INR if on warfarin
- Renal function (dose adjustment)
Reference: BNFc; BNF 90; MHRA Drug Safety Update 2018 (Fluconazole in Pregnancy); BNFc. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.