Brittle nails that peel, split, or crack easily are extremely common and usually signal that your nails have lost moisture, been exposed to too many chemicals, or are reflecting a change happening inside your body. About 35% of people over 60 have brittle nails, but it can happen at any age. The cause is often environmental, though nutritional gaps and certain health conditions can play a role.
Two Types of Brittle Nails
Brittleness shows up in two distinct patterns. The first is horizontal splitting: your nails peel in thin layers at the tip, almost like pages of a book separating. This is caused by dehydration of the nail plate. The second pattern is longitudinal ridging, where vertical lines run from the base of the nail to the tip, giving the surface a rough, textured feel. Ridged nails tend to crack along those vertical lines rather than peeling at the edges.
Both types fall under the umbrella of “brittle nail syndrome,” and they can occur together. Recognizing which pattern you have can help narrow down the cause, since peeling nails are more closely tied to water exposure and chemical damage, while ridged nails are more often linked to aging or underlying health issues.
Why Water and Chemicals Do the Most Damage
Healthy nail plate contains only 7 to 12% water and less than 1% fat. That’s far drier than your skin, which holds 20 to 40% water and around 10% fat. Because nails are already so low in moisture, anything that strips what little water or oil they have makes them fragile fast.
Repeated wetting and drying is one of the biggest culprits. Every time you wash dishes, shower, or soak your hands, your nails absorb water and swell slightly. When they dry out, they contract. That expansion-contraction cycle weakens the bonds between the layers of the nail, eventually causing them to separate and peel. People who work with water frequently (nurses, hairdressers, bartenders, parents of young children) tend to develop brittle nails earlier and more severely.
Acetone-based nail polish remover is another major offender. Acetone is a powerful solvent that strips oils and moisture from the nail plate, and repeated use dries nails out enough to cause visible peeling and cracking. Even acetone-free removers contain solvents like ethyl acetate or isopropyl alcohol that can have a similar, though milder, drying effect over time.
Nutritional Deficiencies That Show Up in Your Nails
Iron deficiency is the most well-documented nutritional cause of nail changes. When iron stores are low, nails can become thin, brittle, and in some cases develop a concave, spoon-like shape called koilonychia. This spoon-shaped deformity appears in roughly 5.4% of people with iron deficiency anemia, and in children, nail changes can actually show up before blood tests detect the deficiency. The brittleness results from impaired production of keratin, the protein that gives nails their structure.
Biotin (vitamin B7) deficiency is less common but worth noting, because supplementation has some of the strongest evidence for improving nail strength. A daily dose of 2.5 mg of biotin has been shown to improve nail firmness, thickness, and resistance to splitting. Most people get enough biotin from food, but those on restrictive diets or with absorption issues may fall short. It takes several months of supplementation to see results, since you’re essentially growing an entirely new nail.
Health Conditions Linked to Brittle Nails
Thyroid disorders are among the most common systemic causes. Thyroid hormones directly control the genes responsible for producing keratin. When thyroid hormone levels drop in hypothyroidism, keratin production slows and the nail plate that grows out is thicker, drier, and more prone to breaking. If your brittle nails came on gradually alongside symptoms like fatigue, dry skin, weight gain, or feeling cold all the time, an underactive thyroid is worth investigating.
Poor circulation can also affect nail quality. Blood flow delivers oxygen and nutrients to the nail matrix (the tissue under your cuticle where new nail cells form). Conditions that reduce circulation to the hands, including Raynaud’s phenomenon and peripheral vascular disease, can produce nails that grow slowly and break easily. This is one reason brittle nails become more common with age: circulation to the extremities naturally declines over time.
Skin conditions like psoriasis and eczema can involve the nail bed directly, causing pitting, crumbling, and separation of the nail from the underlying skin. These nail changes usually appear alongside the condition’s more recognizable symptoms on the skin.
Why Age Matters
Brittle nails affect roughly 35% of adults over 60. Part of this is simple biology: as you age, the nail plate loses a waxy substance called cholesterol sulfate that helps maintain its flexibility. The nail also grows more slowly with age, meaning each section of nail is exposed to environmental wear for a longer period before it reaches the tip. Add in the higher likelihood of reduced circulation and chronic health conditions, and it’s no surprise that nail brittleness is sometimes called a geriatric disorder. That said, it’s not inevitable, and the same treatments that help younger people can improve nail quality at any age.
How to Strengthen Brittle Nails
The most effective approach depends on whether your nails are dehydrated (peeling at the tips) or damaged by an internal cause.
For dehydrated nails, moisturizing is the single most impactful step. Two ingredients stand out for their ability to increase the water-holding capacity of nail plate: urea (in concentrations of 5 to 20%) and lactic acid (5 to 10%). Both are humectants, meaning they pull moisture into the nail and help it stay there. Look for nail-specific creams or thick hand creams containing one or both ingredients, and apply them after washing your hands or bathing, when the nail has absorbed some water and you want to seal it in.
Reducing water exposure helps just as much as adding moisture. Wearing waterproof gloves when washing dishes or cleaning, keeping showers shorter, and avoiding soaking your hands unnecessarily all reduce the wet-dry cycling that weakens nail layers. If you use nail polish remover regularly, switching to an acetone-free formula and limiting use to once a week or less can make a noticeable difference.
For nails affected by a nutritional deficiency or thyroid issue, treating the underlying problem is essential. No topical product will fully correct brittleness caused by low iron or sluggish thyroid function. Once the root cause is addressed, you’ll need to wait for a fully healthy nail to grow in. Fingernails grow at an average rate of about 3.5 mm per month, so replacing an entire nail from base to tip takes roughly four to six months.
When Brittle Nails Point to Something Bigger
Most brittle nails are caused by environmental exposure and improve with simple habit changes. But certain patterns suggest something more is going on. Nails that have changed color (yellow, brown, or with dark streaks), nails that are separating from the nail bed, or nails that have become spoon-shaped all warrant a closer look. Brittleness that appears suddenly, affects both fingernails and toenails, or comes alongside hair loss, fatigue, or unexplained weight changes is more likely tied to a systemic condition than to hand washing or nail polish.