Brittle toenails, known medically as onychoschizia, are characterized by nails that split, peel, or crumble easily. The toenail is primarily made of keratin, a hard protein that also forms hair and the outer layer of skin. Because toenails grow slowly, dealing with breakage can be a frustrating issue. Identifying the specific cause is the first step toward restoring the nail’s strength and resilience.
External and Mechanical Stressors
Physical damage is a frequent cause of toenail brittleness, often stemming from the constant pressure feet endure. Repetitive microtrauma, such as the toes hitting the front of a shoe during running or hiking, weakens the nail plate over time. Tight or ill-fitting footwear, especially shoes with a narrow toe box, places continuous stress on the nails, disrupting their structure and leading to splitting.
Improper moisture balance also causes keratin layers to lose integrity. Nails repeatedly exposed to water and then dried out lose natural oils, resulting in a dry and brittle texture. Conversely, constant over-hydration from wearing damp socks or being in wet environments softens the nail plate, making it weak and pliable.
Chemical exposure strips the nail of its protective components. Harsh solvents like acetone, commonly found in nail polish removers, dissolve the lipids that hold the nail cells together. Frequent application and removal of nail polish dries out the nail plate, contributing to a weaker structure and increased susceptibility to breakage.
Fungal and Infectious Causes
Onychomycosis, a fungal infection of the nail, is a common biological reason for toenail fragility. It is caused by dermatophyte fungi that invade the nail bed and plate. As the fungus proliferates, it consumes the keratin, causing the nail to become discolored, thickened, and crumbly.
The infection often begins as a yellow or white spot at the tip and progresses inward. Fungal growth creates debris underneath the nail, pushing the nail plate up and leading to separation and brittleness. Fungi thrive in warm, moist environments, which is why toenails are affected more frequently than fingernails, especially in those with athlete’s foot.
While fungus is the primary culprit, bacterial infections can also play a role if the nail is compromised. Chronic paronychia, an infection of the skin fold around the nail, can affect the growth matrix and lead to secondary brittleness. Any discoloration, pain, or inflammation accompanying brittleness should be assessed by a healthcare provider to determine the exact pathogen.
Internal Health and Systemic Factors
The cause of brittle toenails sometimes originates from processes within the body, affecting all nails simultaneously. Nutritional deficiencies impair the body’s ability to produce strong, healthy keratin. Low levels of iron, which can lead to anemia, are a frequent systemic cause of brittle nails.
A lack of micronutrients, such as zinc and biotin (vitamin B7), can also manifest as nail fragility. Biotin is involved in keratin production, and supplementation may improve nail integrity. Inadequate dietary protein is also relevant, as nails are composed largely of protein, and this can result in a thinner nail plate.
Underlying medical conditions, particularly endocrine disorders, impact nail health by disrupting metabolism. Hypothyroidism, where the thyroid gland is underactive, causes thin, brittle, and slow-growing nails. Conditions affecting peripheral circulation, such as Raynaud’s syndrome, reduce blood flow to the nail matrix, resulting in a thin and fragile nail. Dermatological conditions like psoriasis or lichen planus can also directly affect the nail matrix, causing textural changes and brittleness.
Managing Brittle Toenails
Addressing brittle toenails involves a combination of protective measures and targeted care. Proper trimming should be done straight across to prevent ingrown nails and reduce splitting. Regularly filing the edges with a fine emery board smooths out irregularities and prevents snags that lead to breakage.
Hydration restores the flexibility of the keratin and is a primary element of at-home nail care. Applying an emollient or cuticle oil to the toenails and surrounding skin daily helps the nail plate retain moisture. Products containing lanolin or alpha hydroxy acids are effective for dry, brittle nails.
Protecting the feet from trauma and dampness is necessary for prevention. Choosing shoes that offer ample space for the toes prevents repetitive pressure on the nails. Selecting breathable socks and allowing shoes to fully dry between uses minimizes the moist environment that encourages fungal growth.
If brittleness persists despite consistent home care, or if it is accompanied by other noticeable symptoms, professional consultation is recommended. Seek medical attention if the nail is painful, severely discolored, thickened, or shows signs of swelling or infection. A doctor or podiatrist can perform tests to rule out an underlying systemic disease or accurately diagnose an infection requiring prescription treatment.