Many people who have psoriasis have nail changes. This can involve:
Pitting on the surface of the nail.
Defects in the nail, such as ridges or crumbling nails.
Yellowish color to the toenails (and sometimes fingernails).
Thickening of the fingernails or toenails.
Spots under the fingernails, such as yellow-red patches.
Separation of the nail from the nail bed.
Total loss of the nail bed.
Nail changes rarely happen without other signs of psoriasis. And sometimes changes in the nails can confirm a diagnosis of psoriasis. Nail problems happen most often in people with psoriatic arthritis.