When a nail plate is lost, the expectation is that a new one will eventually emerge and grow back. This hard, keratinized structure protects the underlying fingertip or toe, and its absence often signals underlying damage or a systemic health issue. Persistent absence or severely stalled regrowth indicates that the nail’s production center is compromised, making it necessary to understand the factors that halt this process.
Understanding How Nails Regrow
The nail plate, which is the part we see, originates from a specialized tissue located beneath the skin at the base of the nail called the nail matrix. This area is often referred to as the “factory” for nail production because it continuously generates new cells that form the nail plate. The visible white crescent shape at the base of the nail, known as the lunula, is actually the only exposed portion of this underlying matrix.
The vast majority of the nail’s growth, approximately 90%, comes from the germinal matrix, which determines the nail’s thickness and curvature. These new cells are produced, keratinized, and then pushed forward to create the hard, durable nail plate. This is a constant process, unlike hair follicles, which have resting phases.
The speed of this process is relatively slow and varies significantly between fingers and toes. Fingernails typically grow at 2 to 4 millimeters per month, meaning a full replacement takes four to six months. Toenails grow much slower, often at 1 to 2 millimeters per month, requiring nine to twelve months for complete regrowth.
Common Causes of Delayed or Stalled Regrowth
The most direct reason a nail fails to return is severe physical damage to the growth center, known as matrix trauma. A crush injury or deep laceration near the cuticle can permanently scar or destroy the nail matrix cells. When the matrix is destroyed, the ability to produce a normal, healthy nail plate is lost, resulting in no regrowth or the production of a deformed, thickened, or ridged nail (dystrophy).
If the trauma was not severe enough to destroy the matrix, the problem may lie in the supporting structures. Scar tissue can form on the nail bed, which is the tissue beneath the nail plate. This scar tissue prevents the new nail plate, as it grows out, from properly adhering to the bed, causing the nail to lift or fail to progress smoothly.
A chronic and untreated infection can also damage the structures necessary for new growth. Severe fungal infections (onychomycosis) or persistent bacterial infections cause inflammation and structural damage to both the nail bed and the matrix. This colonization impedes the matrix’s ability to generate new cells and can lead to the complete separation of the existing nail plate from the bed (onycholysis).
Systemic Conditions That Affect Nail Production
When the problem is not localized to a single digit, it may signal an underlying body-wide issue that disrupts the cell division necessary for nail production. Conditions that affect blood circulation can starve the nail matrix of the necessary nutrients and oxygen. For instance, peripheral artery disease or poorly controlled diabetes can restrict blood flow to the extremities, slowing or halting the metabolic processes needed for keratin production.
Endocrine disorders can also impact the rate and quality of nail growth. Severe, untreated thyroid disorders, such as hypothyroidism or hyperthyroidism, disrupt the body’s overall metabolism. This metabolic imbalance can cause the nails to become brittle, or in some cases, lead to onycholysis where the nail separates from the underlying bed.
Certain medications are well-known to interfere with the rapid cell division that occurs in the nail matrix. Chemotherapy drugs, which are designed to target fast-growing cells, frequently cause temporary cessation of nail growth or shedding of the nail plate, a condition called onychomadesis. Other medications, including some strong antibiotics or retinoids, can also temporarily reduce the growth rate, often leaving horizontal grooves called Beau’s lines as evidence of the interruption.
Autoimmune conditions can directly attack the structures of the nail unit. Diseases like severe psoriasis or lichen planus can cause an inflammatory reaction in the nail matrix, leading to pitting, discoloration, or complete destruction of the nail unit. In these cases, the body’s own immune system is actively preventing normal, healthy nail formation.
Seeking Professional Evaluation
If a full fingernail has not begun to regrow after six months, or a toenail after a year, professional medical evaluation is warranted. This is particularly true if the non-regrowth is accompanied by other concerning symptoms. Persistent pain, discharge of pus, or severe, persistent discoloration suggests an active and ongoing infection that requires prescription treatment.
Consulting a dermatologist or a podiatrist is advisable if you observe a deformed, thickened, or partially grown nail that is worsening over time. These specialists can determine if the nail matrix has been permanently damaged and recommend a management strategy.
If the nail loss or stalled growth affects multiple digits or is accompanied by systemic symptoms like fever or sudden weight changes, it may be the first visible sign of an internal health issue that needs immediate attention.