After a nail separates from the nail bed for whatever reason, it will not reattach. A new nail will have to grow back in its place. Nails grow back slowly. It takes about 6 months for a fingernail and up to 18 months for a toenail to grow back.

How long does it take for a smashed fingernail to fall off?

Unless the area of bleeding is very small, an affected nail will usually fall off on its own after several weeks because the pooled blood has separated it from its bed. A new fingernail can regrow in as little as 8 weeks.

Can you lose a fingernail permanently?

As long as there is no permanent damage to the nail matrix or nail bed, the nail ought to entirely regrow and appear completely normal.