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Systemic Antifungal — Onychomycosis / Tinea Pregnancy: Contraindicated — teratogenic; effective contraception required during and for 2 months after treatment

Itraconazole

Brand names: Sporanox, Itrimul

Adult dose

Dose: Onychomycosis (pulse therapy): 200 mg twice daily for 1 week, repeated monthly × 3 pulses (toenails) or × 2 pulses (fingernails). Continuous: 200 mg once daily for 3 months (toenails). Tinea: 100 mg OD × 15 days or 200 mg OD × 7 days
Route: Oral (capsules — take with food; solution — take fasted)
Frequency: Twice daily (pulse) or once daily (continuous/tinea)
Max: 400 mg/day
Triazole antifungal for onychomycosis (dermatophyte and Candida), tinea corporis, tinea pedis, pityriasis versicolor, and systemic fungal infections. Capsule formulation requires gastric acid for absorption — take with food (or cola drink if achlorhydric); solution has better bioavailability.

Paediatric dose

Dose: 3–5 mg/kg/day mg/kg
Route: Oral (oral solution preferred in children)
Frequency: Once or twice daily
Max: 200 mg/day
BNFc: specialist use — licensed for tinea capitis and systemic candidiasis in children. Oral solution (10 mg/mL) preferred — better bioavailability. Not licensed for onychomycosis in children.

Dose adjustments

Renal

No dose adjustment for capsules in mild-moderate renal impairment; avoid IV formulation if eGFR <30

Hepatic

Use with caution in hepatic impairment — hepatotoxicity risk; monitor LFTs

Paediatric weight-based calculator

BNFc: specialist use — licensed for tinea capitis and systemic candidiasis in children. Oral solution (10 mg/mL) preferred — better bioavailability. Not licensed for onychomycosis in children.

Clinical pearls

  • Contraindicated in heart failure — negative inotropic effect; MHRA warning: do not use in patients with ventricular dysfunction or history of heart failure
  • Potent CYP3A4 inhibitor — one of the most clinically significant drug interactions; always check interactions before prescribing
  • Pulse therapy vs continuous for onychomycosis: equivalent mycological cure rates; pulse preferred — lower total drug exposure, fewer adverse events, better cost-effectiveness
  • Capsule absorption requires acid: take immediately after food or fatty meal; patients on PPIs/H2 blockers have reduced absorption — switch to oral solution
  • Nail culture and microscopy before prescribing — confirms diagnosis (15% of nail dystrophies are not onychomycosis); itraconazole and terbinafine should not be prescribed without confirmation
  • LFT monitoring: only in symptomatic patients during short courses; baseline LFTs recommended before continuous courses >1 month

Contraindications

  • Congestive heart failure (negative inotrope — contraindicated)
  • Pregnancy (teratogenic)
  • Concurrent QT-prolonging drugs (terfenadine, astemizole, pimozide, quinidine)
  • Hypersensitivity to azoles

Side effects

  • Nausea
  • Abdominal pain
  • Hepatotoxicity (rare — check LFTs if symptomatic)
  • QT prolongation
  • Heart failure exacerbation
  • Drug interactions (potent CYP3A4 inhibitor)
  • Hypokalemia
  • Peripheral neuropathy (prolonged use)

Interactions

  • Statins — greatly increased myopathy risk (simvastatin, atorvastatin — suspend during treatment)
  • Warfarin — significantly increased INR
  • Ciclosporin, tacrolimus, sirolimus — increased immunosuppressant levels
  • Midazolam, alprazolam — increased sedation
  • Calcium channel blockers — additive negative inotropy

Monitoring

  • LFTs (baseline for continuous courses; if symptomatic)
  • Symptom response (mycological cure at 6 months post-treatment for toenails)
  • Drug interactions review

Reference: BNFc; BNF 90; BNFc; MHRA Drug Safety Update (Heart failure); BAD Onychomycosis Guidelines 2014; NICE CKS Fungal Nail Infection. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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