there’s a single unbroken line — so no confusion for the brain to sort out and no extra inches. However, all horizontal stripes are not created equal. It was found that narrow black stripes on ...

A small black line that forms vertically underneath your nail may be a splinter hemorrhage, while horizontal lines may be melanonychia. These may be harmless or a sign of a more serious health ...

A black line can also stretch horizontally across the nail (horizontal melanonychia), though this is rare. Depending on the ...

A Reddit user shared a photo of their nail showing a “black line,” and was quickly advised by other users to see a doctor ...