Fingernail peeling, clinically termed onychoschizia, occurs when the nail plate horizontally separates into thin layers at the free edge. The nail plate is composed of multiple compacted layers of keratin, and peeling results from a disruption of the adhesion between these layers. This separation leaves the nail feeling thin, rough, and prone to breaking. Understanding the source, which ranges from environmental stressors to internal imbalances, is the first step toward effective treatment.
External Factors Leading to Nail Splitting
The primary driver of peeling nails is repetitive exposure to moisture fluctuation, which mechanically breaks the bonds holding the keratin layers together. Nails are porous and absorb water, causing them to swell when wet. When the nail dries, it contracts, and this cycle of swelling and shrinking strains the adhesion between the layers. This repeated stress causes the top layers of the nail to lift and peel away, making the condition common for people who frequently wash their hands or handle water.
Exposure to harsh chemicals acts as a secondary form of external trauma by stripping the natural oils and moisture from the nail plate. Cleaning products, detergents, and degreasers are designed to dissolve fats, which also removes the protective lipids within the nail structure. Acetone-based nail polish removers are particularly drying because they rapidly remove surface oils, leading to immediate brittleness. The subsequent dryness increases the nail’s vulnerability to mechanical damage and further splitting.
Mechanical stress from improper technique during manicuring or everyday use also contributes significantly to layer separation. Filing the nail in a back-and-forth motion creates micro-trauma that can fray the layers at the free edge. Excessive buffing can thin the nail plate, removing protective keratin and making the remaining structure fragile. Routinely using fingernails as tools to scrape, pick, or open objects places uneven pressure on the distal edge, forcing the layers to split apart.
Underlying Health and Nutritional Contributors
Internal systemic factors may compromise the structure of the nail from within. The nail matrix, where nail growth originates, requires a steady supply of specific nutrients and hormones to produce a strong keratin plate. A common internal cause is iron deficiency, often presenting as anemia, which can lead to brittle nails. Iron is necessary for proper oxygen transport, and its deficiency affects the health and formation of the nail cell structure.
Deficiencies in certain B vitamins can also impact nail integrity, with biotin (Vitamin B7) being particularly relevant because it plays a role in the production of keratin. Insufficient intake of biotin or other micronutrients like zinc can lead to softer, more fragile nails that break or split easily. Unlike external causes that affect only the fingernails, a nutritional or systemic cause often affects all nails—both fingernails and toenails—and can be accompanied by other symptoms.
Beyond nutritional status, endocrine disorders can manifest as changes in nail texture and strength. Hypothyroidism, a condition where the thyroid gland does not produce enough hormones, is linked to brittle nails. This hormonal imbalance can slow the overall metabolic rate and cell turnover, meaning the nail tissue is older and drier by the time it reaches the free edge. The resulting nail plate is more fragile and susceptible to splitting.
Immediate At-Home Care and Prevention
At-home care focuses on minimizing the damaging effects of moisture cycling and replenishing the nail’s natural lipid barrier. To manage excessive water exposure, wear protective gloves when washing dishes or using cleaning chemicals. Immediately after washing hands, apply a rich moisturizer or specialized nail oil to the nail plate and surrounding skin to seal in moisture and restore lost lipids. This helps to counteract the drying effects of soap and water.
When shaping the nails, use proper technique to prevent further splitting. Opt for a fine-grit nail file and always file in a single direction, rather than a back-and-forth motion. This technique effectively seals the exposed keratin layers at the edge, reducing the opportunity for moisture to penetrate and separate them. Keep nails trimmed relatively short while they are healing, as longer nails are more prone to catching and splitting.
When using nail cosmetics, choose non-acetone polish removers, which are less harsh on the nail’s surface oils. Nail hardeners can provide a temporary protective shield, but they should be used sparingly and according to instructions, as some formulations can ironically increase brittleness if used too often. If home care strategies are consistently followed for several months without seeing an improvement, or if the peeling is accompanied by other symptoms, seeking medical advice is recommended. A healthcare provider can perform blood tests to rule out underlying issues like anemia or thyroid disease, or check for fungal infections, which may require specific treatment.