Fingernails fall off when something disrupts the connection between the nail plate and the tissue underneath it. The cause can be as straightforward as slamming your finger in a door or as gradual as a fungal infection that takes years to reach its most advanced stage. In most cases, the nail grows back completely, though fingernails grow at an average rate of about 3.5 millimeters per month, meaning full replacement takes roughly four to six months.
Injury and Blood Under the Nail
The most common reason a fingernail falls off is direct trauma. Crushing your finger in a door, dropping something heavy on it, or hitting it with a hammer can rupture tiny blood vessels in the nail bed, creating a pool of blood trapped beneath the nail plate. That blood buildup increases pressure, causes throbbing pain, and turns the nail dark purple or black.
In mild cases, the discoloration grows out with the nail over the following months. In more severe injuries, the pressure and damage to the nail bed break the seal holding the nail in place, and the nail loosens gradually before falling off. This process can take days or several weeks depending on how badly the tissue was damaged. If the nail matrix (the root where new nail cells form) wasn’t permanently harmed, a new nail will begin growing in underneath the old one before it detaches.
Fungal Infections
Fungal nail infections are a slow-moving cause of nail loss. The most common culprit is a type of dermatophyte fungus that invades the nail bed, producing a buildup of chalky white debris beneath the nail plate. Over time, the nail thickens, discolors to yellow or brown, and begins to lift away from the bed.
This process is gradual. The most advanced stage of fungal infection, where the nail plate is fully destroyed and may fall off, can take 10 to 15 years of chronic untreated infection to develop. At that point, the nail bed itself is ridged and damaged, and significant debris has accumulated underneath. Toenails are affected more often than fingernails, but fingernail fungal infections do occur, particularly from yeast organisms. Treatment at earlier stages can usually prevent things from progressing to nail loss.
Hand, Foot, and Mouth Disease
One of the more surprising causes of nail shedding is hand, foot, and mouth disease, a common viral illness in children. The infection itself causes fever and small blisters on the hands, feet, and inside the mouth. But four to six weeks after the illness resolves, some children (and occasionally adults) notice their nails beginning to separate and shed.
The shedding typically starts at the base of the nail near the cuticle and progresses outward toward the tip over the course of about two weeks. The viruses responsible, most commonly enterovirus 71 and coxsackievirus A16, temporarily shut down the nail matrix during the acute illness. The nail that was being produced at that time has a structural gap in it, and once that gap grows out far enough, the old nail detaches as a new one pushes up from below. The nails grow back normally.
Psoriasis and Other Skin Conditions
Psoriasis doesn’t just affect skin. When it targets the nail unit, it causes a range of changes that can eventually lead to nail loss. The hallmark sign is pitting, where small dents appear across the nail surface. But psoriasis can also cause the nail to lift away from the bed starting at the fingertip, a process called onycholysis. You might also notice salmon-colored spots beneath the nail, white lines, or a buildup of white chalky material under the nail plate.
Psoriasis-related nail changes result from inflammation in the nail bed or the nail matrix. One or many nails can be involved, and the severity varies widely. In some people, the nail crumbles and disintegrates at the edges. In more severe cases, the combination of lifting, crumbling, and debris buildup leads to partial or complete nail loss. Unlike trauma, where a single event causes the problem, psoriasis tends to create ongoing, recurring nail damage that requires treatment of the underlying condition.
Chemotherapy
Certain cancer drugs, particularly a class of medications called taxanes, are known to cause nail problems as a side effect. These drugs work by disrupting cell division throughout the body, and the nail matrix, which is one of the most actively dividing tissues you have, is especially vulnerable. The result can range from discoloration and brittleness to complete nail shedding.
The mechanism is essentially the same as what happens after a viral illness: the drug temporarily halts nail production, creating a weak point in the nail plate. As the nail continues to grow after treatment, that weak zone eventually reaches a point where the nail separates. Some cancer treatment centers now use cooling devices on the hands and feet during infusions, since narrowing the blood vessels in the fingertips reduces how much of the drug reaches the nail matrix.
Bacterial Infections Around the Nail
An infection in the skin surrounding the nail, called paronychia, can also lead to nail loss if left untreated. This typically starts as redness, swelling, and tenderness along the edge of the nail or at the cuticle. The skin feels warm, and a pocket of yellow or white pus may form.
When paronychia is caught early, warm soaks and sometimes a course of antibiotics clear it up within a few days. But if the infection persists, it can distort how the nail grows, leaving it ridged, wavy, yellow-green, and dry. Eventually the damaged nail can detach from the bed and fall off. In rare cases, an untreated infection can spread deeper into the finger and even reach the bone, so persistent swelling, increasing pain, or spreading redness around a nail warrants prompt medical attention, especially for people with diabetes or compromised immune systems.
Nutritional Deficiencies
Mineral deficiencies rarely cause a nail to fall off entirely, but they can weaken nails enough to contribute to the problem. Iron deficiency can lead to brittle nails that crack easily and begin to separate from the nail bed. Zinc deficiency causes similar brittleness along with horizontal grooves across the nail surface. The most direct nutritional link to actual nail shedding involves calcium: repeated drops in blood calcium levels can trigger spasms in the tiny arteries feeding the nail matrix, cutting off its blood supply long enough to cause the nail to separate at its root. This is uncommon outside of significant, chronic calcium imbalance.
What Happens After a Nail Falls Off
The exposed nail bed looks pink or red and feels tender because it’s essentially raw tissue that’s been protected by a hard covering for months. Keeping it clean and covered is the priority. A light layer of antibiotic ointment under a bandage helps prevent the dressing from sticking to the sensitive surface. Your provider may apply an artificial nail or splint to protect the nail bed while it heals.
New nail growth starts at the base, near the cuticle, and slowly extends outward. At the average fingernail growth rate of about 3.5 mm per month, regrowing a full nail takes four to six months. Toenails grow less than half as fast, closer to 1.6 mm per month, so a lost toenail can take a year or more to fully return. During regrowth, the new nail may look slightly ridged or uneven, but it typically smooths out as it reaches full length, provided the nail matrix wasn’t permanently scarred.
If the nail bed or matrix sustained serious damage from the original injury or infection, the replacement nail may grow in thicker, thinner, or with a permanent ridge. Nails that fall off due to temporary causes like viral illness or chemotherapy almost always regrow normally once the underlying trigger has resolved.