Overview: What is Nail Fungus

 The CPSA gratefully acknowledges Yuliya Lytvyn, PhD, MD candidate, University of Toronto, Richie Jeremian, PhD, MD Candidate, McGill University, and Charles W. Lynde, MD, FRCPC, DABD, FCDA for assistance in the preparation of this report. June 2021.

Nail fungus affects about 8% of Canadians. In 90% of patients, it is caused by fungi (dermatophytes) and less commonly by yeast (Candida). The fungus usually invades the nail at the free edge and then spreads down the side toward the base. Less often, it starts from the base and moves upward. Infection may also occur in patches or streaks on the nail surface. Nail fungus infections are progressive, recurrent, and contagious. Therefore, nail fungus is challenging to manage due to difficulty in diagnosis, frequent recurrences, long-term treatment periods, and potential side effects of oral medications.