Nail fungus is a fungal infection in one or more of your nails. An infection with nail fungus may begin as a white or yellow spot under the tip of your fingernail or toenail. As the nail fungus spreads deeper into your nail, it may cause your nail to discolor, thicken and develop crumbling edges — an unsightly and potentially painful problem.
An infection with nail fungus may be difficult to treat, and it may recur. But medications are available to help clear up nail fungus.
There are different classifications of nail fungus — depending on type of fungus and manifestation — which may have somewhat different signs and symptoms. In general, however, you may have a nail fungal infection — also called onychomycosis (on-i-ko-mi-KO-sis) — if one or more of your nails are:
- 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 also may separate from the nail bed, a condition called onycholysis. You may feel pain in your toes or fingertips and detect a slightly foul odor.
When to see a doctor
Once a nail fungal infection begins, it can persist indefinitely if not treated. See your doctor at the first sign of nail fungus, which is often a tiny white or yellow spot under the tip of your nail.