A recent Alberta Tools for Practice1 summarises that up to 45-60% of patients on oral treatments for fungal nail infections (terbinafine best; NNT=3 and placebo 6%) will be "cured" after ~1 year with 12 to 16 weeks of treatment.
Re terbinafine versus "azoles" (mostly itraconazole), 58% cure with terbinafine, 46% azole; NNT=9. Risk of terbinafine-induced liver injury: ~1 in 50,000-120,000 prescriptions, and taste loss in 0.6 - 2.8% of those taking the drug.2 Advise patient to stop taking at first sign of taste loss as it's usually reversible.
Topicals should be reserved for cases with minimal (<40%) nail involvement. Improvement is 6-23% on topicals (efinaconazole best but not available in NZ, ciclopirox is available in NZ; NNT to get cure 15-23 and treat for up to 48 weeks). Amorolfine is available in NZ but no data was presented.