A nail is a plate of hard keratin that grows out of a fold of skin. It is also a record: fever, a long bath, a harsh remover or a low iron level can each leave a mark that shows weeks later. The American Academy of Dermatology (AAD) and the NHS describe healthy nails the same way, as smooth, one colour and free of dents, and both list the same daily habits to keep them that way.
Most nail trouble in people who wear polish has an ordinary cause: too much water, too much solvent, too much filing and too little oil. The care that fixes it is the same care that keeps polish on longer. Each section links to a fuller guide on its question.
How does a nail grow?
The nail plate is made in the matrix, a strip of dividing cells hidden under the skin fold at the base of the nail. The cells fill with keratin, flatten and are pushed forward. The pale half-moon at the base, the lunula, is the visible end of the matrix. Under the plate, the nail bed is a strip of skin the plate slides over, and the seal under the free edge, the hyponychium, keeps water and microbes out.
Growth is slow and steady. Fingernails grow at about 3 to 4 mm a month and a complete plate takes about six months to replace, according to the Medscape reference on nail anatomy. Toenails grow at roughly half that speed. Growth is faster on the longer fingers, in summer and under the age of 30. Nearly 90% of the plate comes from the germinal (proximal) half of the matrix, so an injury there can leave a permanent groove.
A change you notice today at the free edge was laid down three to six months ago, and a problem you fix today will take that long to grow out. The parts of the nail, and why the matrix matters most, are explained in nail anatomy: plate, matrix, lunula and cuticle.
What makes nails weak, and what keeps them strong?
Water is the biggest everyday stress on a nail. The plate soaks up water, swells, then shrinks as it dries. Repeated many times a day, that cycle loosens the bonds between keratin cells, and the nail splits or peels. The AAD's nail-care tips put water protection near the top: gloves for washing up and cleaning, and a moisturiser after every hand wash.
Solvents are the second stress. Acetone and other removers strip the oils that keep the plate flexible, and dermatologists note that prolonged soaking causes dryness, splitting and white patches on the surface (Sinclair Dermatology). The fix is the same in both cases: shorten the exposure, then replace the oil.
Nails also get older. The NHS lists thicker or more brittle nails as a normal part of ageing, alongside injury, nail biting, fungal infection and long contact with water or chemicals as the common causes of nail problems (NHS, nail problems). Iron deficiency and thyroid disorders are the internal causes that come up most often, so a nail that stays brittle after weeks of care deserves a blood test. The evidence on each cause is set out in brittle nails: causes and care.
Do nails need to breathe, and does diet matter?
The nail plate is fed while it is being made, by the blood vessels under the matrix and nail bed, and the finished plate is dead tissue in the same way that hair is. A coat of polish covers the plate; it does not starve it. A break from polish helps with the remover, the staining and the filing that come with each manicure. A realistic rhythm is set out in do nails need a break from polish, and the permeability claim behind so-called breathable lacquer is examined in breathable nail polish: what it means.
Because the plate is built from the bloodstream, what you eat shows up in it months later. Nails are keratin, a protein, so a diet very low in protein grows thin nails. Iron deficiency can produce thin, spoon-shaped nails. Zinc deficiency is linked to horizontal grooves and white spots, according to the Cleveland Clinic. A varied diet with enough protein, iron and zinc covers most people; the foods and the signs of a shortfall are in nails and diet.
Biotin is the supplement most often sold for nails. The Mayo Clinic suggests asking a healthcare provider whether it might help weak or brittle nails. The evidence is a few small, older studies, and biotin is known to interfere with some laboratory tests. The studies, the doses used and the warning are covered in biotin for nails: what the evidence says.
What does a weekly nail-care routine look like?
Good nail care is a set of small, repeated habits. The daily part takes under a minute. The weekly part is a ten-minute tidy that keeps the free edge smooth and the cuticles soft, so nothing catches and tears.
| How often | What to do | Why it works |
|---|---|---|
| Every day, morning and night | One drop of cuticle oil per nail, massaged into the skin and the plate | Replaces the oil that water and solvents remove; keeps the plate flexible |
| Every day, after each hand wash | Hand cream over the nails and cuticles | Dermatologists advise moisturising after every wash to stop drying and splitting |
| Every wet task | Gloves for washing up, cleaning and gardening | Stops the swell-and-shrink cycle that splits nails and lifts polish |
| Once a week | File the free edge in one direction, push back softened cuticles, check for hangnails | A smooth edge does not snag; a pushed cuticle stays sealed without cutting |
| Once a week | Check all ten nails in daylight for new colour, grooves, lifting or swelling | Changes are easy to miss under polish |
| Every 2 to 3 days while wearing polish | A fresh coat of top coat | Seals the free edge and delays chips, so you remove polish less often |
| Every 1 to 2 weeks | Remove polish with the shortest possible solvent contact, then oil | Limits the drying effect of the remover |
| In winter, or after heavy hand washing | A thick occlusive balm over oil at night (nail slugging) | Traps moisture in the skin around the nail overnight |
You will need
- A fine file, 240 grit or finer, or a glass file
- A cuticle softener or a warm flannel
- A rubber-tipped or stainless-steel cuticle pusher
- Small nippers, for hangnails only
- Cuticle oil and a hand cream
The weekly ten minutes
- Remove any polish, wash and dry your hands.
- File the free edge to shape with strokes in one direction. Sawing back and forth frays the keratin and starts peeling.
- Apply cuticle softener, or hold a warm flannel on the fingertips for a minute. Skip the bowl of water, which swells the plate.
- Push the cuticle back gently. Stop when you feel resistance.
- Nip only loose hangnails. Leave the living skin of the fold alone; the AAD advises against removing the cuticle because it protects the matrix.
- Rub a drop of oil into each nail and the skin around it, then hand cream over the top.
Which oils do what, and how to apply oil over polish, are in cuticle oil: ingredients and how to use it. The cream step is covered in hand cream and your nails.
Should you cut your cuticles?
The cuticle is the thin band of dead tissue that grows out from under the skin fold and sticks to the plate. It seals the gap between fold and nail so that water and bacteria cannot reach the matrix. Cutting it opens that seal. The AAD advises against removing the cuticle because doing so can damage the nail, and the Mayo Clinic adds that picking at cuticles can damage the nail bed and let in infection (Mayo Clinic).
The alternative is to soften and push. A softener or a warm flannel loosens the dead tissue, and a pusher moves it back so that polish can reach the base of the nail. Hangnails, the torn strips of skin at the side of the nail, are the one thing to nip, close to the base and with clean nippers. The method, and the difference between the cuticle and the living eponychium above it, is in cuticle care without cutting.
Which polish habits protect the nail?
Polish itself does little harm; the habits around it decide whether nails stay strong. A base coat is the first: it stops dark pigments from staining the plate and gives colour something to grip, so it chips later and gets removed less often. The India Anaïs base coat, The Base, was made for that job (sold out; the next edition is planned for spring 2027). What a base coat is and when to skip it are in what does a base coat do.
Removal is the second habit. Acetone is the fastest solvent and, used briefly, the least traumatic, because a slow remover means more rubbing. Keep contact short, keep it off the skin, and oil afterwards. The comparison is in acetone vs acetone-free remover.
Gel polish is a separate case. Removing it needs filing and a 10 to 15 minute acetone soak, and peeling it off takes the top cells of the plate with it. Cleveland Clinic dermatologists also point to cumulative ultraviolet exposure from curing lamps and suggest limiting gel to a few times a year (Cleveland Clinic). If you wear gel, the safe removal method is in how to remove gel polish without damage.
What do common nail problems mean?
Most changes that worry people are harmless and have a mechanical cause. A few are signals from elsewhere in the body. A change on one or two nails after a knock or a manicure is local; a change on all ten nails at once is more likely to come from inside.
| What you see | Usual cause | First step | Full guide |
|---|---|---|---|
| Nails that snap or crack easily | Wet-and-dry cycles, solvents, age; sometimes iron or thyroid | Gloves, daily oil, shorter remover contact; blood test if it persists | Brittle nails |
| Thin flakes lifting off the tip | Onychoschizia: water swelling the plate, two-way filing, harsh removers | File one way, oil twice a day, six weeks of patience | Peeling nails |
| Fine lines running base to tip | Normal ageing, dry skin; sometimes iron deficiency or thyroid | Moisturise; a ridge-filling base coat for a smooth finish | Ridges on nails |
| A groove running across the nail | Beau's line: growth paused during illness, fever, chemotherapy or a manicure injury | Let it grow out; see a GP if lines appear on all nails | Ridges on nails |
| White spots or flecks | Leukonychia from a knock to the matrix; occasionally a reaction to a nail product | Wait for them to grow out; see a GP if the whole nail is white | White spots on nails |
| Yellow tint after dark polish | Pigment staining the porous plate, usually without a base coat | Base coat next time; gentle buffing; polish-free days | Yellow nails after polish |
| Yellow, thick, crumbly nail, often a toenail | Fungal infection; rarely yellow nail syndrome | Pharmacist or GP; treatment takes months | When to see a doctor |
| Sore, red, swollen skin beside the nail | Paronychia, an infection of the nail fold, often after a cut cuticle or a hangnail | See a GP; the NHS lists this as a reason to book | When to see a doctor |
Long-term use of nail polish can leave a yellow or brownish tint on the plate, notes the MSD Manual; a base coat prevents most of it. A yellow nail that thickens and stops growing needs a doctor.
How do seasons and housework change nail care?
Winter is hard on nails: cold, dry air outside and heated, dry air inside both pull water out of the skin around the nail, and the plate follows. The answer is more oil, applied twice a day, gloves outdoors, and a thick occlusive balm at night when cuticles crack. Dermatologist Angela Lamb, quoted by Today, explains the night balm this way: a thick emollient traps in moisture and prevents evaporation of water across the skin surface. The seasonal plan is in nail care in winter.
Housework is the other constant. Washing up, wet cleaning and gardening each mean minutes of soaking, and detergents dissolve the plate's own oils faster than plain water. A pair of cotton-lined rubber gloves by the sink does more for nails than a strengthener. Why water is the main enemy of both nails and polish, and how to dry and moisturise afterwards, is in nails, water and household cleaning.
When should you see a GP or dermatologist about your nails?
Most nail changes grow out on their own. A small number need a medical opinion. The NHS advises seeing a GP when a nail has changed shape or colour, or fallen off, and you do not know why, and when the skin around a nail is sore, red, swollen and warm (NHS).
The AAD lists twelve changes a dermatologist should examine (AAD). The most important is a new or changing dark streak running from the base of a nail to the tip, which can be a melanoma of the nail unit and needs prompt assessment. The others are a lifting nail, redness and swelling around a nail, a greenish-black colour, pitting, yellow nails that thicken and stop growing, deep grooves across the nail, thick overgrown nails, spoon-shaped nails, washboard ridges on the thumbs from picking, nails that curve down over the fingertip, and unexplained colour changes on all the nails.
Book an appointment when
- A dark line appears under a nail without an injury, or a line widens or darkens: see a doctor promptly.
- A nail is lifting, pitted, thickened, or has stopped growing, or the skin beside it is hot, red and swollen.
- All ten nails change at once (grooves, colour, shape), which points to an internal cause.
- Brittle or peeling nails have not improved after three months of gloves, oil and gentle care, or you have diabetes and notice any nail change.
A GP can check iron, thyroid and blood sugar, treat infection and refer on. A dermatologist examines the nail under magnification and can sample it for fungus or biopsy a dark streak. The full list of warning signs, and what each specialist checks, is in nail changes: when to see a doctor.
“A thick emollient traps in moisture and prevents evaporation of water across the skin surface.”
Dr Angela Lamb, Dermatologist, quoted by Today
- Fingernails grow about 3 to 4 mm a month, so today's care shows in three to six months and today's damage takes as long to leave.
- Water and solvents are the two everyday causes of weak nails; gloves, short remover contact and daily oil reverse most of it.
- Push cuticles back after softening; cutting them opens the seal that protects the matrix from infection.
- A change on one nail after a knock is usually local; a change on all ten nails at once is more likely to come from inside the body.
- A new dark streak under a nail, a lifting nail, or hot swollen skin beside a nail needs a GP or dermatologist, not a home fix.
Questions people ask
How can I make my nails stronger?
Reduce the two things that weaken keratin: water and solvents. Wear gloves for wet work, keep remover contact short, and put oil on the nails and cuticles twice a day. File in one direction and keep the edge slightly rounded. Give it three months, the time it takes new plate to reach the tip.
How fast do nails grow?
Fingernails grow about 3 to 4 mm a month and a full nail takes around six months to replace. Toenails grow at roughly half that rate. Growth is faster in summer, in younger people and on the longer fingers.
Is it bad to wear nail polish all the time?
The polish film itself does not harm the plate, which is fed from the blood supply beneath it, not from the air. The removal is what dries nails, so the limit is really on how often you remove and reapply. A base coat prevents staining, and a few polish-free days after each removal let the plate rehydrate.
Does biotin help nails?
A few small, older studies suggest biotin may thicken brittle nails, and the Mayo Clinic suggests discussing it with a healthcare provider. Biotin supplements can also interfere with some blood tests, including thyroid and heart tests, so tell your doctor if you take one.
When should I worry about a nail change?
See a doctor for a new or changing dark streak under a nail, a nail that lifts or stops growing, hot swollen skin beside a nail, or a change on all ten nails at once. The NHS also advises a GP visit for any nail that changes shape or colour without a reason you know.
How often should I put oil on my cuticles?
Twice a day is the usual advice: once in the morning and once at night. One drop per nail, massaged into the skin fold and across the plate. Oil can go over polish, since it feeds the skin and the plate edge, not the lacquer.
- American Academy of Dermatology, 11 dermatologists' tips for healthy nails
- American Academy of Dermatology, 12 nail changes a dermatologist should examine
- NHS, Nail problems
- Medscape, Nail anatomy
- Mayo Clinic, Fingernails: do's and don'ts for healthy nails
- Cleveland Clinic, Ridges in nails
- Cleveland Clinic, Gel nail polish and nail health
- Sinclair Dermatology, Acetone nail polish remover explained
- MSD Manual, Deformities, dystrophies and discoloration of the nails
- Today, What is nail slugging