A split nail, medically known as onychoschizia, occurs when the nail plate develops cracks or layers that separate. This common issue can manifest as horizontal splits across the nail’s tip or vertical splits running along the nail’s length. Understanding nail growth and contributing factors helps manage and prevent this condition.
How Nails Grow and Heal
The visible nail plate consists of dead, keratinized cells, so a split nail cannot “grow back together.” New nail cells are continuously produced by the nail matrix, a specialized area located at the base of the nail, underneath the cuticle. These new cells push older cells forward, causing the nail to grow. A split in the existing nail cannot repair itself; it must grow out as a new, healthy nail emerges from the matrix.
Fingernails grow at about 3.5 millimeters per month. Toenails grow slower, around 1.6 millimeters per month. A complete fingernail replacement takes three to six months, while a toenail requires twelve to eighteen months to fully regrow. Patience is necessary while waiting for a split nail to grow out.
Why Nails Split
Nail splitting stems from external and internal factors. Frequent moisture exposure, such as repeated wetting and drying, is a common external cause, stripping nails of natural oils and leading to dehydration and brittleness. Harsh chemicals in cleaning products, detergents, and nail polish removers also weaken the nail plate, making it prone to splitting. Physical trauma, like bumping, crushing, or habitual nail biting or picking, can directly cause splits or weaken the nail structure.
Internal factors also affect nail health. Nutritional deficiencies, particularly iron deficiency, can lead to brittle nails, sometimes resulting in spoon-shaped indentations (koilonychia). While less common, biotin deficiency has also been linked to brittle nails. Aging can cause nails to become drier, grow slower, and be more prone to brittleness and splitting due to decreased moisture retention and changes in protein structure. Certain medical conditions, such as psoriasis, eczema, or thyroid disorders, can also cause nail splitting.
Caring for a Split Nail
Managing a split nail involves protecting existing damage and promoting healthy new growth. Gently filing the nail in one direction helps prevent the split from worsening and catching on objects. Regular moisturizing of the nails and cuticles, especially after hand washing, maintains nail hydration. Products containing ingredients like alpha hydroxy acids or lanolin can aid in this process. Protecting nails with gloves during activities involving water or chemicals prevents further dehydration and weakening. Avoiding habits like picking or tearing the nail is important to prevent additional trauma.
While nail strengtheners can create a protective barrier and temporarily reinforce the nail, they do not heal the split itself. These products often contain ingredients like nylon fibers or keratin to provide temporary support. The split portion of the nail must grow out completely before the nail returns to its healthy state.
When to Seek Professional Advice
While many split nails can be managed with home care, certain signs indicate professional medical attention may be necessary. Consult a doctor or dermatologist if nail splitting is persistent or recurs despite consistent home care. Concerning symptoms include pain, swelling, or redness around the nail, suggesting an infection. Pus, unusual discoloration (such as black, green, or yellow), or significant changes in nail shape or thickness also warrant evaluation. If multiple nails are affected without a clear external cause, or if splitting accompanies other systemic symptoms, it could indicate an underlying medical condition like a fungal infection, thyroid issue, or nutritional deficiency.