Distal subungal onychomycosis. Scrapings from distal aspect under nail plate are often positive in KOH. If negative KOH, consider culture prior to treatment.

White superficial onychomycosis. Chalky white scrapings taken from the nail surface are KOH positive.

Proximal subungal onychomycosis. The nail surface is smooth. The infection is beneath the nail plate.

Multiple finger nails affected by onychomycosis. A positive KOH or culture is advised before treatment. Infection can be spread to skin by scratching.