Most of the time a missing nail is growing back, just far more slowly than people expect. Toenails in particular can take over a year to fully replace.
Nails are made by living tissue hidden under the skin at the base, so the real question is whether that tissue is healthy, not how the visible nail looks today. When growth truly stalls, the cause is usually one of a handful: an injured root, an infection, poor circulation, or a recent illness or drug that hit pause.
How Long a Nail Really Takes to Grow Back
In healthy young adults, fingernails grow about 3.5 mm a month on average.1PubMed. Growth rate of human fingernails and toenails in healthy American young adults Toenails grow less than half as fast, about 1.6 mm a month.2PubMed. Growth rate of human fingernails and toenails in healthy American young adults That means a fingernail usually replaces itself in roughly 4 to 6 months. A lost big toenail commonly takes 12 to 18 months to grow fully back.
Age slows things further. Nail growth drops by about half over a lifetime,3PubMed. The effect of aging on the rate of linear nail growth so an older adult’s toenail can take noticeably longer than a teenager’s.
In the first weeks after losing a nail, the bed may look bare, pink, or slightly thick while new nail forms underneath the skin fold. The new nail isn’t made on the surface of the bed. It’s made at the base and slides forward, so the first sign is a thin pale edge at the back, not anything at the tip. Until the new nail reaches the end of the toe or finger, the exposed bed often hardens into a rough, dry surface. That’s a normal protective change. A new toenail that looks thick or uneven in its first months is also common, since it’s growing out over a recently injured bed.
The 12 to 18 month figure is an average, so you may land at either end of it without anything being wrong. To judge your own pace, mark where the new edge sits against the skin fold at the base and compare after a month or two, not week to week. A dated photo each month makes real progress easy to see.
An Injured Nail Root Can Change or Stop Regrowth
Your nail is produced by root tissue under the skin at the nail’s base, whose cells constantly divide. A crush, deep cut, or slammed-door injury that reaches this tissue can disrupt the whole nail that follows. Trauma can also leave scars running along, across, or diagonally through the nail bed.4PubMed Central. Nail bed injuries and deformities of nail A narrow scar may let the nail still attach, while a wide one leaves the nail lifting off.5PubMed Central. Nail bed injuries and deformities of nail
What matters is how deep the injury went and whether it reached the root or the bed, not how painful or bloody it looked. Since the scar sits beneath the nail, the damage often doesn’t show until the new nail has grown far enough to reveal it, sometimes many months later.
The scar’s direction shapes what you see. A lengthwise scar tends to show as a groove or split in the same place each time the nail grows forward. A scar across the bed can stop the nail sticking down in that spot, so it lifts beyond that point.
Signs that the root, not just the nail, was hurt include a split or ridge that grows out in the same line every time, a new nail lifting from the bed, a nail much thinner, narrower, or more misshapen than before, and very little regrowth after several months despite no infection.
Scars can sometimes be repaired. For a problem scar, a surgeon can remove the nail, cut out a narrow scar and close the bed, or graft new nail bed tissue if needed.6PubMed Central. Nail bed injuries and deformities of nail A nail that keeps lifting or splitting at the same spot after an injury is worth showing to a hand surgeon or dermatologist.
A large blood blister under the nail or a cut in the nail bed is best seen within days, because proper repair at the time gives the best chance the new nail grows flat. Scars that set in are harder to fix and may need surgery later.
Infection and Swelling Around the Nail
Repeated inflammation of the skin around the nail makes the folds swell, harden, and pull back.7PubMed Central. Management of Chronic Paronychia The protective seal and cuticle are lost, letting moisture, germs, and irritants collect in the grooves.8PubMed Central. Management of Chronic Paronychia Flare-ups then keep returning and the cuticle can’t grow back, a cycle that can last months.9PubMed Central. Management of Chronic Paronychia The inflamed fold also gradually loses its blood supply.10PubMed Central. Management of Chronic Paronychia
Long-lasting inflammation there can disturb how the nail is made, and the new nail may grow with ridges, dents, or an uneven surface. That’s why a nail can look wrong long after the red, sore stage seems to have settled: the nail you see now was made while the fold was inflamed.
To break the cycle at home, keep your hands dry and wear cotton-lined gloves for wet work. Don’t push back or cut cuticles while the fold is sore, and stop picking or biting the area, which reopens the gap. If swelling lasts more than a few weeks, see a doctor; prescription creams are often needed.
Inflammatory skin disease can also damage the nail. Lichen planus, an itchy purplish skin rash, can thin and ridge the nails.11PubMed Central. Biologics and Small Molecules for Inflammatory Nail Disorders: A Narrative Review If untreated, it can scar the base and lead to permanent nail loss.12PubMed Central. Biologics and Small Molecules for Inflammatory Nail Disorders: A Narrative Review
Fungal nail infection makes nails thick and crumbly and can make a regrowing nail look abnormal. Fungus usually spreads slowly and may affect several nails, while injury changes usually start from one event and one nail, though these patterns overlap and aren’t a reliable way to tell them apart. A clinic test of nail clippings confirms fungus before you commit to months of treatment.
When the Nail Grows Backward Into the Skin
Sometimes a nail becomes ingrown backward, embedding into the skin fold at its base.13PubMed Central. Chronic Retronychia: Nonsurgical Treatment Several layers of nail stack up under the fold instead of growing forward.14PubMed. Retronychia of the toenails: a review with emphasis on pathogenesis, new diagnostic and management trends It starts when an injury disturbs forward growth, pushing the old nail back into the fold.15PubMed. Retronychia: proximal ingrowing of the nail plate It mostly affects toenails and is linked to repeated knocks like tight shoes or running, poor circulation, and childbirth.16PubMed. Retronychia of the toenails: a review with emphasis on pathogenesis, new diagnostic and management trends The base stays red and swollen and the nail seems not to grow.17PubMed. Retronychia: proximal ingrowing of the nail plate Typically a big toenail stops moving forward and looks yellowish or lifted, with a puffy, tender fold of skin at the base.
It’s easily mistaken for a fungal infection or a simple ingrown nail, because the nail looks yellow or thick and the area is sore. But an ordinary ingrown nail digs in at the side, while here the trouble is at the base and the nail seems to stop growing forward.
Switch to roomy shoes and avoid repeated toe pressure. A doctor may treat mild cases with steroid cream, while persistent cases often need the stacked nails removed so a new one can grow.
Illness, Fever, and Medicines That Pause Growth
During serious illness the body can temporarily stop making nail, leaving Beau’s lines, which are grooves across the nail.18PubMed Central. Unravelling Beau’s Lines as a Potential Indicator of Severe Immune Response in Covid-19 and Reinfection In high fever the body prioritizes vital organs over nail growth.19PubMed Central. Beau’s Lines and COVID-19; A Systematic Review on Their Association Severe COVID-19 has been linked to these lines.20PubMed Central. Beau’s Lines and COVID-19; A Systematic Review on Their Association In very severe illness, such as intensive care, nails can detach and shed entirely.21PubMed. Critical illness onychomadesis The groove marks when you were sick and grows out over months.
The groove appears in the visible nail only after the paused section has grown out from under the skin, so it may turn up weeks after the illness itself. Toenails show it later and for longer, because they grow more slowly and the mark takes longer to reach the tip.
You can roughly date a groove. Measure from the cuticle to the groove in millimetres, then divide by about 3.5 mm a month on fingernails for a rough estimate of how many months ago the illness hit, since growth rates vary with age and health.
Chemotherapy works on the same principle. Cancer drugs attack rapidly dividing cells, and the nail root’s cells are among them.22PubMed Central. Nail Changes With Chemotherapeutic Agents and Targeted Therapies Nails usually recover after treatment ends.
During treatment, keep nails short and moisturized, and avoid harsh polish removers and acrylics. Tell your oncology team about painful or lifting nails.
Poor Circulation and Nerve Damage
Peripheral artery disease (PAD) narrows leg arteries and reduces blood flow to the toes.23PAD Treatment Centers | USA Vascular Centers. Peripheral Artery Disease & Toenails The nail root then gets less oxygen and nutrients, and new toenail grows poorly.24PAD Treatment Centers | USA Vascular Centers. Peripheral Artery Disease & Toenails With poor leg circulation, ingrown or fungal nails and small cuts can turn into serious problems because healing needs blood.25Foot Health Facts. Peripheral Arterial Disease
Look for calf pain when walking that eases with rest, and for cool, pale, or shiny skin and little hair on the toes. Smokers, people with diabetes, and older adults are at higher risk. A toenail that has stopped regrowing, together with these signs, calls for a doctor visit, not home nail treatment.
If you have diabetes or poor leg circulation, never dig out an ingrown nail yourself. Check your feet daily for cuts or color change, and let a podiatrist trim thick nails.
Nerves matter too. Damage to the main nerves of the hand is usually followed by slower fingernail growth.26PubMed. An abnormality of nail growth associated with median nerve damage A nail on a finger numbed by an old wrist or arm injury may therefore grow back slower than the others.
Habits and Rarer Causes
Repeatedly picking or rubbing the cuticle can cause a ridged nail, dark streaks, infection, and permanent damage.27Cureus. Nail-Associated Body-Focused Repetitive Behaviors: Habit-Tic Nail Deformity, Onychophagia, and Onychotillomania Because the root is injured again and again, the damage shows up in each new section of nail until the habit stops. Letting the cuticle heal is often the treatment.
A habit-tic nail typically has washboard ridges down the middle of the thumbnail. Usually the index finger is rubbing the cuticle without you noticing. Covering the thumb with tape or a bandage for weeks lets it reset.
Uncommon causes exist as well. Small growths in the nail unit, such as glomus tumors, can distort the nail, and skilled surgery lowers the chance of lasting damage.28PubMed Central. Surgical Management of Difficult Nail Glomus Tumors Some people are born with missing or underdeveloped nails from genetic conditions like nail-patella syndrome.29PubMed Central. Nail-Patella Syndrome Associated with Short Stature: A Case Series
Red flags for a growth include sharp pain with cold or pressure at one spot under the nail, or a dark streak that widens or spreads onto skin. A single nail changing for no reason deserves a dermatologist’s look.
When to See a Doctor and What They Can Do
Book a visit if there’s no new nail at the base after about three months. A healthy nail usually shows at least a thin new edge by then. That wait is for a nail with no other warning signs. Spreading redness, warmth, pus, or throbbing pain call for a visit right away. So do diabetes, PAD, or numb feet with any nail wound, a dark streak or lump, and changes on several nails at once.
Treatment is matched to the cause. Trapped blood or pus under a nail can be drained to relieve pressure.30Semilac. Damaged Nail Matrix – How to Treat, What Are the Causes? A nail detaching from its root may be removed so a new one can grow cleanly.31Semilac. Damaged Nail Matrix – How to Treat, What Are the Causes? A scarred nail bed can be repaired surgically, as with the scar repair described earlier.32PubMed Central. Nail bed injuries and deformities of nail
Bring when and how the nail was hurt or lost, dated photos showing growth, and a list of medicines and recent illnesses. Mention habits like picking or tight work boots too.
In the meantime, keep the bed clean, dry, and covered while it’s tender. Wear roomy shoes for toenails, and skip gels and acrylics until the nail is fully grown.