Flaky toenails are usually caused by one of three things: repeated moisture exposure that weakens the nail structure, a fungal infection, or a nutritional shortfall. The good news is that most causes are identifiable and treatable, though some take patience. Here’s how to figure out what’s going on with your nails and what to do about it.
Repeated Wetting and Drying Is the Most Overlooked Cause
Your toenails are made of layered sheets of a tough protein called keratin, held together by a kind of intercellular “cement.” When those layers lose their bond, the nail surface peels apart in thin flakes or splits horizontally. Dermatologists call this onychoschizia, and it’s the most common form of brittle nail syndrome.
The primary trigger is cycling between wet and dry. Every time you soak your feet (in a bath, pool, or shower) and then let them air-dry, the nail plate swells and contracts. Over time, this weakens the adhesion between keratin layers. Healthcare workers, swimmers, people who wear sweaty shoes for long shifts, and anyone who washes their hands or feet frequently are especially prone. Chemical exposure compounds the problem. Acetone-based nail polish removers are harsh and drying to the nail plate, and aggressive buffing or scraping during pedicures can physically injure the surface. Harsh soaps and household cleaners have a similar dehydrating effect.
Nails become brittle when their water content drops below about 16%. So the paradox is real: too much water exposure actually leads to dried-out, flaky nails because of the repeated swelling and shrinking cycle rather than sustained hydration.
Fungal Infections Affect Up to 10% of Adults
Fungal nail infections (onychomycosis) account for roughly half of all nail disorders worldwide. The global prevalence sits around 10%, and that number climbs sharply with age: about 20% of people over 60 and 50% of those over 70 are affected. Warm, humid climates push rates even higher.
The fungi responsible produce enzymes that literally digest keratin, the protein your nail is made of. As the organisms burrow deeper into the nail plate, the nail becomes rough, soft, and crumbly. You’ll typically notice the nail turning white, yellow, or brownish, thickening unevenly, and crumbling or flaking at the edges. The big toe is the most common target because it endures the most pressure and warmth inside shoes.
Risk factors include wearing closed-toe shoes in hot weather, walking barefoot in communal wet areas like gym showers or pool decks, having diabetes or a weakened immune system, and having an existing skin condition like athlete’s foot (which is caused by the same family of fungi and can spread to the nails).
How Fungal Flaking Differs From Simple Brittleness
With moisture-related flaking, the nails usually look normal in color and just peel at the surface. Fungal infections tend to produce color changes (yellow, white, or brown discoloration), thickening of the nail, and debris building up underneath. The nail may also start to lift away from the nail bed. That said, distinguishing the two on appearance alone can be difficult, and a healthcare provider may need to take a small nail clipping to test for fungus under a microscope.
Nail Psoriasis Can Look Almost Identical
Psoriasis affects the nails in roughly half of people who have the skin condition. The most recognizable sign is pitting: small dents or divots scattered across the nail surface, almost like someone pressed a pin into it. Other signs include a chalky white appearance, reddish spots near the base of the nail, thickening underneath, and the nail pulling away from the skin below.
Because nail psoriasis and fungal infections share several features (thickening, lifting, crumbling), they’re notoriously hard to tell apart without testing. They can even occur at the same time. Having psoriasis elsewhere on your body, especially on your scalp, elbows, or knees, is a strong clue that your flaky nails may be psoriasis-related.
Nutritional Deficiencies That Show Up in Your Nails
Your nail plate is built from a mix of proteins and minerals in specific proportions, so almost any significant nutritional gap can show up as changes in nail texture. The deficiencies most strongly linked to flaky, peeling nails include:
- Iron: Low iron can cause brittle nails that split, crack, or peel. Nails may also become spoon-shaped in more advanced deficiency.
- Magnesium: Reduced plasma magnesium levels are associated with soft, flaky nails that are prone to breaking and splitting.
- Zinc: Zinc deficiency causes brittle nails with vertical ridging and sometimes horizontal grooves.
- Biotin: A B vitamin involved in keratin production. Deficiency leads to dystrophic, peeling nails.
- Calcium: Low calcium is linked to soft nails with longitudinal ridges and increased brittleness.
Older adults are particularly vulnerable because poor food and water intake directly contributes to nail brittleness. If your flaky nails are accompanied by fatigue, hair thinning, or other systemic symptoms, a nutritional deficiency is worth investigating with a simple blood test.
What You Can Do at Home
If your flaking seems related to dryness and environmental exposure rather than infection, the single most effective strategy is reducing moisture cycling. Wear waterproof gloves for cleaning. Dry your feet thoroughly after bathing, especially between the toes. Limit long soaks. Avoid acetone-based polish removers, or at minimum reduce how often you use them.
Moisturizing the nail plate helps restore flexibility. Urea-based creams are particularly effective because urea acts as both a moisturizer and a mild keratolytic, meaning it softens thickened, rough nail tissue. Over-the-counter products with 20% to 40% urea can help smooth flaky surfaces and rehydrate the nail. Lactic acid and allantoin-based products work similarly. Apply them at night and cover with socks to keep the product in contact with the nail.
For suspected fungal infections, over-the-counter antifungal nail lacquers exist, but topical treatments alone require at least 12 months and have low cure rates. Prescription oral antifungals are significantly more effective. In one study, combining an oral antifungal with a urea preparation boosted the complete cure rate from 8% to 57%. Regardless of approach, toenails grow slowly (about 1 to 1.5 millimeters per month), so even after successful treatment, it takes 12 to 18 months for a fully healthy nail to replace the damaged one.
Signs Worth Getting Checked
Flaky nails on their own are common and often harmless, but certain changes suggest something more is going on. Watch for color changes like yellow, brown, green, or dark streaks. Thickening that makes the nail hard to trim, the nail separating from the skin underneath, pain or soreness around the nail, and any sign of redness or swelling that could indicate a secondary infection all warrant a visit to your doctor or a podiatrist. Even minor foot and nail problems can progress to infections more easily than you might expect, especially if you have diabetes or poor circulation.