Why Nails Become Black?

There are several causes of nails becoming black. One of the major reasons for black nails is trauma. If you wear too tight or loose shoes, your nails may become black. Fungal infection and injury can also cause your nails to turn black. Melanoma (a type of skin cancer) is the most serious issue of nails turning black. Cancer can grow under the nail bed and can cause pigmentation on the skin.