Retronychia happens when a nail stops growing outward and grows back into the skin. Wearing ill-fitting shoes can cause retronychia by putting pressure on toenails. Treating retronychia early with ...

Fingernails grow 3.47 millimeters a month; toenails grow 1.62 millimeters a month. Taking biotin supplements may strengthen nails and promote their growth. Avoid using nail cosmetics regularly, as ...