Onychomycosis is the fungal infection of the nail apparatus affecting between 10% and 30% of the global population, the causative agents being dermatophytes, yeasts, and rarely nondermatophyte molds. Dermatophyte infection, mostly due to Trichophyton rubrum, is the most prevalent one.
Current treatment options include both oral and topical drugs, with oral therapies giving better outcomes. Terbinafine should be considered as first line medication for dermatophyte onychomycosis, itraconazole being its best alternative.
On the other hand, itraconazole should be considered as first line treatment in yeast infections, where terbinafine is not indicated. Nondermatophyte molds generally do not respond well to the usual systemic medications, but the therapeutic outcome may be improved by removal of the diseased nail, followed by treatment with topical antifungals or the use of new generation azoles.
Oral therapy of onychomycoses is limited by adverse events and drug drug interactions, whereas topical therapy has limited penetrance through the nail plate. New and reformulated drugs are in development, experimental molecules include both oral and topical azole molecules, oxaboroles, and photosensitizers.