You may have a toenail fungal infection — also called onychomycosis (on-i-ko-mi-KO-sis) — if one or more of your nails are:
Thickened
Brittle, crumbly or ragged
Distorted in shape
Dull, with no luster or shine. A dark color, caused by debris building up under your nail.
Infected toenails may also separate from the nail bed, a condition called onycholysis. You may even feel pain in your toes or fingertips and detect a slightly foul odor.
