Toenails fall off when something disrupts the connection between the nail plate and the nail bed underneath it. The most common causes are injury, fungal infections, and skin conditions like psoriasis, though systemic illnesses and certain medications can also trigger nail loss. In most cases, a new nail will grow back, but toenails grow slowly (about 1.6 mm per month), so full replacement typically takes 12 to 18 months.
Trauma and Repetitive Pressure
A single hard impact, like dropping something heavy on your toe, can cause bleeding underneath the nail plate. This pooled blood is called a subungual hematoma. Normally there’s no space between your nail plate and the tissue beneath it, so when blood collects there, it creates pressure that pushes the nail upward. If the pressure is severe enough or goes untreated, the nail separates from the bed and eventually falls off.
You don’t need a dramatic injury for this to happen. Runners, soccer players, and basketball players frequently lose toenails from repetitive microtrauma: the toe bumping against the front of the shoe thousands of times over weeks or months. Ill-fitting shoes are a major contributor. The nail may turn dark purple or black first, then loosen gradually over several weeks before detaching. If you catch a subungual hematoma early, a healthcare provider can drain the blood through a small hole in the nail to relieve the pressure and sometimes save it.
Fungal Infections
Fungal nail infections (onychomycosis) are among the most common reasons toenails detach. The fungi responsible, usually a group called dermatophytes, produce enzymes that break down keratin, the protein your nails are made of. In the most typical pattern, the fungus enters at the tip of the nail and works its way backward, invading the nail bed and the underside of the nail plate. This triggers mild inflammation and causes the tissue under the nail to thicken. Two things result: the nail lifts away from the bed, and the area underneath becomes thick and crumbly.
A species called T. rubrum is responsible for the vast majority of toenail fungal infections, accounting for up to 90% of cases. Infected nails usually change color (yellow, brown, or white), become brittle, and thicken before they start to separate. The process is slow, often developing over months. Because the nail is compromised from underneath, it may crumble apart rather than detach in one piece. Treatment usually involves antifungal medication, and the full course can last months because the nail needs time to grow out completely.
Psoriasis and Other Skin Conditions
Nail psoriasis can look remarkably similar to a fungal infection, which makes it easy to confuse the two. Both can cause the nail to thicken, change color, and separate from the bed. Psoriasis, however, tends to produce a few additional signs: tiny pits or dents in the nail surface, a rough sandpaper-like texture, and small reddish spots near the base of the nail (the lunula). Salmon-colored patches under the nail and tiny splinter-like lines of bleeding are also characteristic.
Because the overlap is so significant, providers often use lab tests (microscopy, culture, or molecular testing) to check for fungus before settling on a diagnosis. This matters because the treatments are completely different. Interestingly, people with nail psoriasis are also more susceptible to fungal infections on top of their psoriasis, and the fungal species involved tend to differ. In psoriatic patients, yeast infections (particularly Candida) are more common than the dermatophytes that dominate in the general population.
Illness, Medication, and Systemic Causes
When your body goes through a serious illness or metabolic stress, nail growth can slow dramatically or stop entirely. The nail-producing cells at the base of the nail (the matrix) pause their activity, creating a horizontal groove that grows outward over time. If the disruption is severe enough, the nail plate loses all continuity with the matrix. As healthy nail begins growing behind it, the new growth wedges the old plate upward and eventually pushes it off entirely. This process, called onychomadesis, typically becomes visible four to eight weeks after whatever triggered it.
The list of triggers is long. Chemotherapy drugs are the most common medication-related cause, and they usually affect all 20 nails at once, with changes appearing two to three weeks after treatment begins. Retinoids and certain anti-seizure medications can do the same. On the infectious side, hand-foot-and-mouth disease is a well-known trigger in children: nail shedding shows up four to six weeks after the illness. Other infections linked to this kind of nail disruption include measles, scarlet fever, and severe bacterial infections. Chronic conditions like uncontrolled diabetes and Raynaud’s disease (where blood flow to the extremities is reduced) can also compromise nail growth enough to cause shedding.
What Happens After a Toenail Falls Off
Once a toenail detaches, you’re left with an exposed nail bed, which is tender and vulnerable to infection. Keeping it clean and covered is the priority. A light layer of antibiotic ointment can prevent a bandage from sticking to the raw tissue. Change the dressing daily unless instructed otherwise. Your provider may give you a protective splint or specialized shoe to shield the toe while it heals.
The nail bed itself typically hardens within a few weeks, but regrowth is a long process. Toenails grow at an average rate of about 1.6 mm per month, roughly half the speed of fingernails. A big toenail can take a full 12 to 18 months to completely replace itself. The new nail may look slightly different in texture or shape at first, but it usually normalizes as it reaches full length.
Signs of Infection to Watch For
An exposed nail bed is an open door for bacteria. Watch for increasing redness, swelling, and pain around the nail, especially near the cuticle or any broken skin. Pus-filled blisters are a strong signal of bacterial infection. If you notice red streaks spreading away from the toe, develop a fever or chills, or experience joint or muscle pain, the infection may be spreading beyond the local area and needs prompt medical attention.