Changes in nail color can have a variety of causes. Some are benign, while others may call for medical attention. According to Christine Kingsley, black lines on the nails are typically caused by “minor trauma or injury to the nail bed,” such as “hitting your finger on a hard surface or as a result of repetitive stress on the nail.” In this case, they will gradually fade and don’t require professional treatment. However, black or brown lines on the nails can also be indicative of more serious underlying conditions such as melanoma — a type of skin cancer. In rare cases, they may also be signs of “a systemic disease such as lupus or endocarditis,” adds Kingsley.
While these are possible causes for dark-colored discoloration of the nail plate, a lesser-known cause is melanonychia, a benign condition where a higher concentration of pigment is deposited into the skin. “When you have more melanin in your skin, some of the melanin can deposit into the nails, which causes these brown lines,” Ashley Ann explains.
Both Kingsley and Ann agree that any recurring or abnormal changes in the nails should get checked by a medical specialist for an accurate diagnosis and timely treatment. For instance, if melanoma is the cause of inconsistent nail coloring, it should be treated promptly. The condition can become more dangerous and difficult to treat once it has progressed further into the skin or other parts of the body.
