What causes brittle, peeling nails?

Most often it's everyday wear, not a health problem: repeated wetting and drying, harsh soaps and cleaning products, nail polish removers (especially acetone), gel manicures, low humidity, and age. Constant water exposure is a big one — it swells and shrinks the nail until the layers separate. Less commonly, brittle nails can be linked to iron, thyroid, or other systemic issues.

Does biotin actually work for brittle nails?

The honest answer: the evidence is weak and limited. A few small, older studies suggested high-dose biotin over many months might help genuinely brittle nails, but the trials were small and not well controlled, and there's little proof it helps if you're not deficient. It's generally safe, but don't expect much — and note biotin can interfere with some lab tests, so tell your doctor if you take it.

How can I make my nails stronger?

Protect and hydrate them: wear gloves for washing up and cleaning, limit acetone removers and frequent gels, moisturize your nails and cuticles like you would your skin, keep nails a bit shorter while they recover, and file gently in one direction. Strength comes mostly from reducing damage, not from a product that 'hardens' them.

Brittle, Splitting & Peeling Nails, Explained

Brittle nails that split, peel, or break easily are one of the most common nail complaints — affecting up to a fifth of people, and more women than men, especially over 50 (PMC, 2020). The good news: it's usually about wear and tear, not a deficiency, and a few habit changes help more than any "miracle" product.

What's actually happening

Nails are made of layers of keratin held together and kept flexible by a small amount of moisture and natural oils. When that structure is disrupted, you get (PMC, 2020):

Onychoschizia — peeling or splitting of the nail into layers, usually at the tip.
Onychorrhexis — vertical ridging and lengthwise splitting.

The everyday causes

For most people, brittle nails come down to hydration and damage, not diet:

Repeated wet–dry cycles (dishes, cleaning, frequent hand-washing) that swell and shrink the nail until layers separate.
Harsh chemicals — soaps, cleaning products, and acetone nail polish removers.
Frequent gel or acrylic manicures and aggressive removal.
Low humidity and age, both of which reduce the nail's moisture.

Less often, brittle nails accompany a systemic cause like iron deficiency or thyroid problems — which is worth checking if the change is sudden or comes with other symptoms.

What actually helps

Think "reduce damage and add moisture," the same way you'd treat dry skin (AAD):

Wear gloves for washing up, cleaning, and gardening.
Moisturize nails and cuticles — a cream or oil, especially after hand-washing. Ingredients like hyaluronic acid and emollients help hold water.
Go easy on removers and gels; take breaks between manicures.
File gently in one direction and keep nails a little shorter while they recover.

The honest truth about biotin

Biotin (vitamin B7) is the internet's favorite nail supplement, but the evidence is thin. A handful of small, older, poorly-controlled studies suggested high-dose biotin over several months might modestly help genuinely brittle nails — but there's little proof it does anything if you aren't deficient, and modern reviews consider the evidence weak (PubMed, 2017). It's generally safe, but manage your expectations, and note one practical catch: biotin can distort certain lab tests (including thyroid and heart tests), so tell your doctor if you take it.

When to see a doctor

Brittle nails are usually cosmetic. But see a doctor if all your nails change at once, the change is sudden, or it comes with other symptoms (fatigue, hair changes, brittleness elsewhere) — these can point to an underlying issue worth testing. And get any dark streak, single oddly-changing nail, or non-healing area checked, rather than assuming it's simple brittleness — see what your nail changes can mean.

Not sure whether a nail or skin change is just wear and tear or something to look into? A dermatrix.life skin assessment gives you a private, plain-language starting point from photos you upload — informational only, not a diagnosis, and never a substitute for a professional. (How it works.)