If several sites are involved, topical treatments
have failed or if the hair or nails are affected, then
systemic (oral) antifungals are recommended.
Laboratory confirmation of infection is preferred
before systemic prescribing unless there is a high
index of suspicion. This is because of the
sometimes prolonged treatment courses required
(at least three months in the case of infected
toenails), the rare but potentially serious side
effects, and the non-urgent nature of the condition
(Drug and Therapeutics Bulletin 2002).