Dark streaks appearing under the nails should be taken more seriously, especially if they develop suddenly or change in size, color, or shape. In some cases, these streaks can be a warning sign of melanoma, a type of skin cancer that requires prompt medical evaluation. Not every dark mark is dangerous, but unusual changes should not be ignored.
White horizontal lines, sometimes called Muehrcke’s lines, may be associated with changes in the body’s protein levels or certain health conditions affecting organs such as the liver or kidneys. These lines can provide clues about internal health, especially when they appear alongside other symptoms.
Nails can reflect what is happening inside the body, but they do not provide a diagnosis on their own. Many nail changes have harmless explanations, including normal aging, minor injuries, or temporary stress. The key is noticing changes that are new, unusual, or progressing.
After the age of 40, it becomes especially important to pay attention to nail health. A sudden difference in texture, color, or pattern may be a simple issue, but it can also be an early sign that something needs attention.
