Medically reviewed by Susan Bard, MD A black line on the nail could be normal, such as when it is just a color variation.

You probably know by now that your nails can tell you a lot ... They do not require treatment because they will grow out naturally. Splinter hemorrhages could be a sign of a serious health concern ...

Splinter hemorrhages typically grow out with the nail, but if they attach to the ... The discoloration usually appears 3-8 ...