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Antifungal — Oral Candidiasis Pregnancy: Avoid — systemic fluconazole associated with fetal cardiac defects at high doses; single 150 mg dose data inconclusive; use nystatin topically in pregnancy

Fluconazole

Brand names: Diflucan

Adult dose

Dose: 150 mg single dose (oropharyngeal candidiasis, mild); 50–100 mg once daily for 7–14 days (more severe or immunocompromised)
Route: Oral / IV
Frequency: Once daily or single dose depending on indication
Max: 400 mg/day (invasive candidiasis)
Used for oropharyngeal candidiasis (thrush), denture stomatitis, and pharyngeal candidiasis in ENT. Especially important in immunocompromised patients (HIV, chemotherapy, corticosteroid use — including inhaled steroids). Single 150 mg dose for mild OPC; longer courses for recurrent or severe disease.

Paediatric dose

Dose: 6 mg/kg on day 1, then 3 mg/kg daily mg/kg
Route: Oral / IV
Frequency: Once daily
Max: 12 mg/kg/day (max 800 mg in invasive infection)
BNFc: oropharyngeal candidiasis — 3 mg/kg daily for 7 days (neonates: 3 mg/kg every 72h; <2 weeks: every 72h)

Dose adjustments

Renal

Reduce dose or increase dosing interval if eGFR <50 mL/min/1.73m²

Hepatic

Use with caution — hepatotoxicity reported; monitor LFTs in prolonged use

Paediatric weight-based calculator

BNFc: oropharyngeal candidiasis — 3 mg/kg daily for 7 days (neonates: 3 mg/kg every 72h; <2 weeks: every 72h)

Clinical pearls

  • Inhaled corticosteroid (ICS)-associated oral candidiasis: advise patients to rinse mouth and gargle with water after each ICS dose — nystatin lozenges for prophylaxis, fluconazole for treatment
  • HIV-positive patients: recurrent oropharyngeal candidiasis is an AIDS-defining illness — check CD4 count; long-term fluconazole prophylaxis if CD4 <200
  • Significant warfarin interaction — potent CYP2C9 inhibition; INR can double or triple with short course; monitor within 3–5 days
  • Denture stomatitis: treat both the patient (fluconazole/nystatin) and the denture (soak in antifungal solution) — failure to treat denture leads to relapse
  • QT risk with high doses — check ECG if combining with QT-prolonging drugs

Contraindications

  • Hypersensitivity to azole antifungals
  • Coadministration with QT-prolonging drugs metabolised by CYP3A4 (terfenadine, astemizole, pimozide, quinidine, amiodarone)
  • Cisapride (contraindicated)

Side effects

  • Nausea
  • Headache
  • Transient LFT elevation
  • QT prolongation (at higher doses)
  • Hepatotoxicity (prolonged use)
  • Rash (Stevens-Johnson rare)

Interactions

  • Warfarin — significantly increases INR (fluconazole is a potent CYP2C9 inhibitor — INR check within 3–5 days)
  • Statins — increased myopathy risk (simvastatin/atorvastatin — suspend during treatment)
  • Phenytoin — increased phenytoin levels
  • Ciclosporin — increased levels

Monitoring

  • Symptom response (5–7 days)
  • LFTs (prolonged use)
  • INR (if on warfarin)
  • QTc (if on QT-prolonging drugs)

Reference: BNFc; BNF 90; BNFc; BSAC Oral Candidiasis Guidelines; NICE CKS Oral Candidiasis. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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