A fungal nail infection often begins with the appearance of a small white or yellow spot under the tip of a nail. As the fungus spreads, other symptoms develop. You should seek medical care if you notice any of the following:
- Whitish or yellowish spots or streaks either in the skin under a nail (the nail bed) or on the underside of the nail itself
- A thickened or distorted nail
- A brittle, ragged nail
- A nail with a dull or powdery appearance
- A nail that is crumbling at its outside edges
- A darkened (brown or gray) nail
- A nail that has separated from its nail bed (a condition called onycholsis)
- A nail that has a foul odor
- A nail that is painful