Oral antifungals compared
A comparison of the three most-used oral antifungals for skin and nail fungal infections: terbinafine, itraconazole and fluconazole. Spectrum, doses, interactions, adverse effects and level of evidence. Informative content; it does not replace medical assessment.
| Feature | Terbinafine | Itraconazole | Fluconazole |
|---|---|---|---|
| Family | Allylamine | Triazole | Triazole |
| Mechanism of action | Inhibits squalene epoxidase (fungicidal against dermatophytes) | Inhibits ergosterol synthesis (14-alpha-demethylase) | Inhibits ergosterol synthesis |
| Main spectrum | Dermatophytes (very active) | Broad: dermatophytes, yeasts and some moulds | Yeasts (Candida); less active against dermatophytes |
| Typical indications | Onychomycosis and dermatophyte tinea (first choice) | Onychomycosis, pityriasis versicolor, candidiasis, extensive mycoses | Candidiasis, pityriasis versicolor; alternative in onychomycosis |
| Indicative dosage | 250 mg/day | 200 mg/day (or pulse regimens) | 150-300 mg/week |
| Usual duration (toenails) | ≈ 3 months | ≈ 3 months or pulses | 6-12 months (longer) |
| Interactions | Few (CYP2D6 inhibitor) | Many (potent CYP3A4 inhibitor) | Moderate-high (enzyme inhibitor) |
| Adverse effects | Digestive, taste disturbance, rare hepatotoxicity, rashes | Digestive, hepatotoxicity, oedema; caution in heart failure | Digestive, hepatotoxicity; generally well tolerated |
| Monitoring | Liver function if prolonged treatment or risk | Liver function; review interactions | Liver function |
| Pregnancy | Avoid | Contraindicated | Avoid |
| Evidence (dermatophyte onychomycosis) | High (first choice) | High | Moderate |
All these antifungals are prescription medicines and require medical indication and follow-up. Doses are indicative and should always be adjusted to clinical judgement. When a fungal infection does not respond, the diagnosis should be confirmed before changing treatment.