Lines on the nails can develop for a range of reasons, from skin conditions to nutritional deficiencies.
We’ll take a closer look at what they may indicate.
Nail care is not only a matter of appearance; it can also reflect overall health, as changes in the nails sometimes point to underlying conditions.
One of the most common visible changes is ridging on the nails. While often harmless, these grooves can sometimes signal systemic issues or nutrient deficiencies.
A study published in the Indian Dermatology Online Journal notes that fingernail ridges tend to offer more reliable indicators than toenail ridges. Here’s why these lines appear and what they may mean.
What causes lines on the nails?
Lines on the nails can form for several reasons, ranging from skin disorders like atopic dermatitis or eczema to deficiencies in protein, calcium, zinc, and vitamin A. Their direction and depth can help provide clues about the cause.
Vertical lines
Vertical ridges run from the cuticle to the tip of the nail. In older adults, mild vertical lines are common and are usually linked to a slowdown in cell turnover, as new cells take longer to replace older ones at the surface.
When accompanied by other changes such as discoloration or texture changes, they may suggest an underlying condition. In trachyonychia, for example, which can occur on its own or alongside other skin disorders, nails may become rough, brittle, and discolored.
Vertical lines may also appear in people with iron deficiency anemia. In some cases, changes in nail shape can even cause a spoon-like, concave appearance.
Horizontal lines
Horizontal ridges, known as Beau’s lines, are more often associated with significant illness. These indentations can temporarily disrupt nail growth until the underlying issue is addressed.
Beau’s lines may appear in cases of acute kidney disease, and when present across all 20 nails, they can be linked to conditions such as mumps, thyroid disorders, diabetes, or syphilis. A study published in Acta Haematologica also notes their occurrence in patients undergoing chemotherapy.
Injury or trauma can also lead to red or brown discoloration under the nails. However, it is important not to confuse these changes with signs of more serious conditions such as endocarditis or melanoma, where dark brown, black, or red discoloration may appear and should be evaluated carefully.