You may have a nail fungal infection — (also called onychomycosis) — 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 nails 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.