Horizontal lines, often called Beau’s lines, can indicate a past illness, significant physical stress, or chronic conditions such as diabetes or circulation problems.

Vertical ridges are common with aging, but if they appear unusually deep or uneven, they may point to nutritional deficiencies, including low levels of iron or vitamin B12.

Dark streaks in the nails should be taken seriously, especially if they appear suddenly, as they may be a sign of melanoma, a serious form of skin cancer that requires prompt medical evaluation.

White lines, known as Muehrcke’s lines, can be associated with liver or kidney issues, or low protein levels. After age 40, noticeable changes in your nails—particularly unusual lines—should not be ignored, as they may serve as early warning signs of underlying health concerns.