Is your recovery window still open? Free one-page chart ↓
Your Nail Is a Slow-Motion Record. Read It Right.
A fingernail grows roughly 3mm a month, so a full nail takes about six months to replace itself. After a crush or a nail bed injury, the final shape usually isn’t clear until 6 to 12 months.
That single number explains most of what people find alarming. A ridge, a groove or a white line appearing now was made weeks ago, and the illness or injury that caused it has usually already resolved.
It also means a damaged nail bed doesn’t declare its final result for half a year.
Two mistakes cost people a normal nail.
- Treating a crushed fingertip as “just a black nail”. If the bed underneath is torn and nobody checks, it can heal scarred. The nail then grows split or ridged, and that’s usually permanent.
- Watching a dark streak for a year, sure it’s an old bruise. Bruises grow out. One rare kind of streak doesn’t, and that’s the one that gets diagnosed late.
Everything else on this page is reassurance, with dates.
How long does a fingernail take to grow back after an injury?
The nail plate is just a hard covering. The thing that decides how the nail grows back is the bed underneath it and the matrix at the base, hidden under the cuticle.
Damage the matrix and the nail grows back split, ridged, thickened or not at all. Damage only the bed and it usually recovers well. This is the reason a crushed fingertip is about the nail bed rather than the fracture.
- Week 0 to 4: the old nail often lifts and falls off. Normal. Don’t pull it early; it’s a dressing.
- Month 1 to 3: new nail emerges from the cuticle, often thickened, ridged or discolored.
- Month 3 to 6: the new nail reaches the tip and its appearance improves considerably.
- Month 6 to 12: final result. Nothing about a nail should be judged before six months.
Nails are a slow-motion record. What you’re looking at today happened a month or two ago.
Will my nail grow back normal after a crush?
Usually, yes, if the matrix and bed weren’t badly torn, or if they were repaired properly early.
- Bruise under an intact nail, no fracture: most grow back normal or near-normal.
- Nail bed tear that was repaired: often a good nail, sometimes a small ridge or a slightly uneven edge.
- Matrix damage, or a tear that wasn’t repaired: higher chance of a permanent split, ridge or a nail that lifts at the tip.
- Bone involved too: a tuft fracture under the nail heals in its own time. The tip often stays tender for a few months after the bone is stable.
This is where the window sits. The nail bed’s window is OPEN in the first day or so after the injury, when a torn bed can be stitched back flat. It starts closing once the bed heals in whatever shape it’s left in. By 6 to 12 months it’s SHUT: the nail you have is the nail you’ll keep, and the goal changes to living well with it or, for some, a planned revision by a hand surgeon.
Black nail after crushing a finger: should it be drained?
Blood trapped under the nail after a crush is intensely painful because it has nowhere to go. Draining it (a small hole through the nail) relieves that immediately and is a quick procedure. It works best in the first day or two, before the blood clots.
But it should be done by someone who has first considered whether there’s a fracture or a nail bed tear underneath. Large collections under the nail often indicate a significant nail bed laceration, which may need repairing. An X-ray is usual if the tip was properly crushed.
(Please don’t do it yourself with a heated paperclip. I know the internet says you can. The internet also said planking was a good idea.)
Should I remove a nail that’s lifting off?
- No, leave it. A lifting nail protects the tender bed underneath and acts as a splint for the fold at the base.
- Trim the loose free edge so it doesn’t snag on clothing.
- Tape or a fingertip cover keeps it in place. See fingertip protector splints.
- Let it come off on its own as the new nail pushes underneath.
Recovering the fingertip, not just the nail
The nail gets the attention. The fingertip is what you actually use. After a crush or nail bed repair:
- End joint bending: once your surgeon or doctor is happy, hold the middle segment of the finger with your other hand and bend just the tip. 10 slow reps, 3 to 4 times a day. Stops the end joint stiffening while everything heals.
- Desensitization: once the skin is healed, tap and rub the tip on different textures (soft cloth, then towel, then rice) for 2 to 3 minutes, several times a day. A tender tip that’s avoided stays tender.
- Protection: a fingertip protector for knocks while it’s sore.
- Cold sensitivity: very common after fingertip injuries. It usually improves, but slowly, over months to a year or two. Gloves help.
When can I go back to work after a nail bed injury?
- Desk work and typing: often within a few days, with the tip protected.
- Light manual work: usually about 2 to 4 weeks, with a protector.
- Heavy gripping, tools, sport: when the tip tolerates pressure. If there’s a fracture, longer, and the tip can stay tender for a few months.
- Wet work (kitchen, cleaning, healthcare): once the wound is fully healed and your doctor is happy, with gloves.
For the full picture on crushed tips, see crush injuries of the hand and fingertip injuries. If it’s a child’s finger caught in a door, start with this page.
What do ridges, lines and pits on fingernails mean?
A horizontal groove across one nail (Beau’s line). The nail stopped growing briefly. Measure back from the cuticle, roughly a month per 3mm, and you’ll usually land on an illness, a fever, chemotherapy or the injury itself. Across several nails at the same level, it points at something that affected the whole body.
Vertical ridges. Almost always just age. Extremely common and rarely significant.
A vertical groove running the length of one nail, on a finger with a lump at the end joint. That’s pressure on the matrix from a mucous cyst. Treat the cyst and the groove usually grows out.
White spots or lines. Usually minor knocks to the base of the nail. They grow out.
Pitting, like a thimble. Points at psoriasis or psoriatic arthritis, particularly with sore end joints.
Spoon-shaped nails. Can indicate iron deficiency. Worth a blood test.
Clubbing: nails curving over increasingly bulbous fingertips, developing over months. That one is a genuine medical flag and needs a doctor.
Dark streak on a fingernail: when to worry
A dark streak running lengthways down a single nail, which is new, widening, darker at the base, or spreading pigment onto the surrounding skin.
That last feature, pigment on the skin at the nail fold, is the one that matters most. Doctors call it Hutchinson’s sign. It can indicate a melanoma under the nail, which is often mistaken for an old bruise and therefore diagnosed late.
A bruise grows out. A streak that stays in the same place, or widens, does not. If you cannot remember an injury and it has been there for months, get it looked at rather than watched.
A simple check: take a photo now, with a ruler beside it. Compare in 4 weeks. Blood from an injury moves toward the tip as the nail grows (about 3mm a month). A streak that starts at the cuticle and stays there isn’t a bruise.
The reassuring part: multiple dark streaks across several nails are common and usually normal, especially in people with darker skin. It’s the single, changing, widening one that warrants a look.
Get it checked today if
- A crushed nail is under tense, throbbing pressure from trapped blood.
- The nail is torn off, the nail fold is cut, or the tip is crushed open. Those need cleaning, checking for a fracture and often a repair.
- The finger is red, hot, swollen and throbbing, or there’s pus at the nail fold. That’s a paronychia or a deeper infection.
Get it checked if
- A single dark streak is new, widening, or pigment is spreading onto the skin.
- One nail is thickening, lifting or crumbling with no injury behind it.
- Fingertips are becoming bulbous with curving nails.
- Six months after an injury, the nail is still splitting, lifting or growing in a way that catches on everything.
Most nail changes are history, not news. The exception is a single dark line that is changing, and that one is worth a photograph and an appointment.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. A freshly crushed fingertip deserves a proper look at what’s under the nail, today.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.