If you notice that your toenails have become dark and discolored, you’re likely to suspect a fungal infection. It’s true that this is a very common cause of dark nails – in about half of cases, nail fungus is the cause – but there are also other reasons why your nails may discolor. A nail biopsy is performed in order to make the proper diagnosis.


This is a type of skin cancer that can affect the bed of the nail, causing dark stripes that run down the nail itself. It’s dangerous if left untreated, but fortunately it can usually be cured if caught early.

  • Melanoma usually only affects a single nail, and the pattern and color will change over time.
  • Dark stripes are common, especially in people of color. However, most dark stripes are not caused by melanoma.

Scar tissue

A common cause of dark nails is scar tissue in the skin beneath the nail, for example if you have badly stubbed your toe. If your nail has become loose because of this, it may also become dark.

  • Clean your nails very carefully to avoid infection. Infections beneath your nails can be extremely painful.
  • Loose nails will usually fall off completely eventually. They will grow back, but this will take many months.


This is a disease that’s not fully understood, but which causes red, itchy patches on the body. It’s very common for people suffering from psoriasis to have dark, discolored nails. It can be treated in several ways, so ask your podiatrist for the best option for you.

  • Nails affected by psoriasis have a very distinctive color, as though there were oil trapped underneath your nail.
  • It’s very common for people with this condition to see small pits in the plate of their nails.

Lichen planus

In this condition, areas of your body – which can include your nails – are discolored in a way that makes them look like lichen. This disease cannot be cured, but there are many treatments which will reduce the symptoms.

  • People with lichen planus often notice that their nails have become very thin and brittle.
  • In one in ten people with this condition, the surface of the nail has a rough texture, similar to sandpaper.