Brittle Nails: Causes, Symptoms and How to Keep Nails Strong
Brittle nails that break easily and peel in layers are very common in dermatology practice, especially in people who are regularly in contact with water and cleaning products. They become more common with age and are seen more often in women than in men.
The most common misunderstanding is that brittle nails mean a “vitamin deficiency”, followed by rushing to buy supplements. In reality, most brittle nails are caused by mechanical and environmental factors acting directly on the nail plate, not by a nutritional deficiency. In this article, a dermatologist explains what the real causes are, which beliefs the evidence does not support, and how to care for your nails so that it actually works.
What are brittle nails?
Brittle nails (Brittle Nail Syndrome) describe a condition in which the nail plate loses its flexibility and strength, so that it cracks, breaks, chips or peels in layers more easily than normal.
The nail plate is made of keratin cells stacked in layers, held together by intercellular material, with water making up roughly 10–30% of the nail’s weight depending on environmental humidity. When the nail loses water or the material binding the layers is damaged, the keratin layers separate and the nail becomes brittle. This is why treating the “nail surface” works better than treating the “diet” in most patients.
Clinically, brittle nails fall into 2 main patterns, which hint at different causes:
Onychoschizia (horizontal peeling in layers): the nail plate splits into thin sheets at the free edge. This pattern is most strongly linked to repeated wetting and drying, and it responds well to changes in habits.
Onychorrhexis (longitudinal ridging and splitting): ridges and grooves run lengthwise from the base to the tip of the nail, together with longitudinal splits at the tip. It is usually linked to older age and to disease at the nail base (nail matrix).
How do brittle nails differ from wavy nails?
Many patients use the terms “brittle nails” and “wavy nails” interchangeably, but medically they are different conditions with different mechanisms and different approaches to care.
Brittle nails of the Onychoschizia type are nails that split and peel in layers at the tip. The problem lies in the adhesion between keratin layers. Wavy nails, on the other hand, are nails whose surface is uneven, with ridges or raised grooves running across the nail. They result from uneven nail production by the nail matrix, and they must also be classified as vertical or horizontal waves, because the two types have entirely different sets of causes.
The two conditions often occur together, especially in older adults, whose nails commonly develop both vertical ridges and increased brittleness. If you have both, start with moisture and chemical exposure first, and then assess whether the remaining waves have features that need further investigation.
What causes brittle nails?
The most common cause is not diet but what the nails come into contact with every day. In order of how often they are seen in the clinic:
Repeated wetting and drying (the number one cause): each time the nail absorbs water and then dries, the nail plate swells and shrinks. Repeating this many times a day, for example washing dishes, doing laundry, cleaning work, food service work, or any job that requires frequent hand washing, weakens the bonds between keratin layers and makes the nail peel in layers.
Solvents and cleaning products: acetone in nail polish remover is a major culprit because it directly dissolves the lipids between cells. Dish soap, laundry detergent and alkaline cleaning products have a similar effect.
Gel and acrylic nails: the problem usually lies not with the gel itself but with filing the nail surface before application, soaking in acetone for a long time to remove it, and prying or peeling off the gel by oneself, which pulls away layers of the nail surface along with it.
Nail hardeners containing formaldehyde: used briefly, they may make nails feel harder, but with continued use the nails become hard to the point of being brittle, break easily, peel off, and may cause contact allergic dermatitis around the nail.
Increasing age: nail growth slows and the nail plate’s ability to hold water declines with age. This is a common cause in older adults and is the reason brittle nails often come with vertical ridges.
Hormonal changes: women after menopause often notice that their nails and skin become drier at the same time, which is associated with lower estrogen levels.
Nail and skin diseases themselves: nail fungus, nail psoriasis, irritant contact dermatitis and chronic inflammation around the nail can all make nails brittle and misshapen. In this group, the underlying disease must be treated, not just the nail cared for.
Systemic diseases: thyroid disorders, iron deficiency anemia, chronic kidney disease, and conditions that reduce blood flow to the fingertips, such as Raynaud’s disease.
Certain medications: oral retinoids and some chemotherapy drugs can make nails thin and brittle during treatment.
Which nutrient deficiency causes brittle nails?
This is the most frequently asked question, and also the point where information on the internet is most inaccurate.
The straightforward answer: in people who eat normally, brittle nails are usually not caused by a nutrient deficiency. A vitamin or mineral deficiency severe enough to change the nails is uncommon, and when it does occur there are almost always other body symptoms before or alongside it, not brittle nails alone.
The nutrients that have evidence linking them to genuine nail abnormalities are listed below. Note that each one causes a different pattern from ordinary brittle nails:
Iron: iron deficiency is associated with spoon-shaped nails (koilonychia), in which the nail flattens and its edges rise into a dip, not with nails peeling in layers. If suspected, serum ferritin and a complete blood count should be checked first. You should not buy iron to take on your own, because too much iron is harmful to the liver and digestive system.
Protein: severe protein deficiency, for example in malnutrition or after certain weight-loss surgeries that reduce absorption, can truly make nails thin and brittle, but it is almost never seen in people who eat a normal diet.
Zinc: clear zinc deficiency causes horizontal grooves on the nails (Beau’s lines) together with a rash around the mouth and the anus, which looks very different from ordinary brittle nails.
Biotin (vitamin B7): this needs to be explained clearly. See the details in the next section.
What the evidence does not support: calcium is not the main component of nails. Nails are made of keratin, which is a protein, so taking extra calcium does not make nails harder, and “white spots on the nails” (leukonychia) do not mean calcium deficiency as commonly believed. Almost all of them come from minor knocks to the nail base several weeks earlier, and then move out gradually as the nail grows.
Which vitamin makes nails strong?
The most honest answer is that no vitamin has yet been proven to make the nails of people who are not deficient any stronger.
Biotin (vitamin B7) is the most heavily advertised. What the evidence actually says is:
The studies reporting that biotin helps nails are small, with only a few dozen participants, mostly without a control group, and conducted only in people who already had brittle nails, so they are not yet considered high-quality evidence.
There is no large randomized controlled study confirming the benefit of biotin for nails in the general population.
True biotin deficiency is very rare in people who eat normally, because biotin is found in many foods and gut bacteria produce some of it.
An important caution that is often overlooked: high-dose biotin interferes with laboratory tests that use immunoassay techniques. It can distort thyroid hormone results and can make troponin, which is used to diagnose a heart attack, read lower than the true value. The US Food and Drug Administration has issued a clear warning about this. If you are taking biotin supplements, tell your doctor and the laboratory staff every time before a blood draw.
As for collagen, silica, vitamin E and selenium, which are often advertised as nail-nourishing, there is currently not enough good-quality evidence to recommend them as a treatment for brittle nails.
In practical terms: if there are no other signs of a nutrient deficiency, the money and time spent on supplements will give less benefit than wearing gloves when washing dishes, stopping acetone, and applying nail moisturizer consistently, which are the three measures that really work and are not expensive.
What causes pale nails?
Pale nails means that the nail bed, which should normally be pink, looks white or faded. This is a different matter from brittle nails, but the two are often searched together because both make nails look unhealthy. The possible causes are as follows:
Cold weather or temporary constriction of blood vessels: the most common cause and not dangerous. The nails return to pink when the hands warm up.
Anemia: usually all fingers are pale at the same time, together with pale eye linings and lips, tiredness and palpitations. If iron deficiency has lasted a long time, spoon-shaped nails may also be seen.
Chronic liver disease: Terry’s nails may be seen, in which almost the whole nail is white with only a narrow pink band at the tip of the nail.
Chronic kidney disease: half-and-half nails may be seen, in which the half of the nail nearest the base is white and the half near the tip is darker, with a clear dividing line.
Low blood albumin: causes several parallel white bands across the nail (Muehrcke’s lines), which disappear when albumin returns to normal.
If pale nails affect all fingers at once, persist, or come with other body symptoms, see a doctor for blood tests to find the cause. On the other hand, if the nail turns dark or has a black band running lengthwise, that is a different group of problems that needs to be assessed differently. Read how to tell them apart in Black nails: what causes them and are they dangerous?
Symptoms and appearance of brittle nails
Brittle nails have several features you can notice yourself:
Nails that chip and break easily at the edges: nails chip or break with only a little force, so you cannot keep them long.
Onychoschizia: the nail peels in thin layers at the tip, and you can see stacked sheets.
Onychorrhexis: there are cracks and grooves running lengthwise from the nail base to the tip.
Changes in nail appearance: the nail is unusually thin, the surface is rough and uneven, lacks shine, and the edge is not sharp.
Pain: some people have pain at the fingertip when the nail tears deep into the nail bed.
What helps tell them apart is the distribution. Brittle nails from use are usually found on several fingers in a similar pattern, develop gradually, and are worse on the hand that does more work.
Brittle nails that are not just brittle nails
If what you see differs from ordinary brittle nails, especially if there is a change in color or thickness, or only one finger is affected, think of other conditions and get examined:
Nails that thicken, turn cloudy yellow or brown, have crumbly debris under the nail, and often start with one finger before spreading → think of nail fungus, which must be confirmed by testing before starting medication, because oral antifungal medicines have to be taken for many months.
Nails with small pinpoint pits, oil-drop-colored spots under the nail, or nails separating from the nail bed → think of nail psoriasis.
Clear ridges or grooves on the nail surface, whether vertical or horizontal → see how to tell them apart in wavy nails, because horizontal waves may reflect a past illness that needs more history.
Swelling, redness and tenderness around the nail, or loss of the cuticle → think of inflammation around the nail (paronychia), which, when chronic, makes newly grown nails misshapen and brittle as well.
The corner or edge of a toenail digging into the flesh with pain and swelling → this is an ingrown toenail, which is solved by caring for the nail edge, not by nourishing the nail.
A brown or black band running lengthwise on a single nail, especially if the band is widening, the color is uneven, or the color spreads to the skin around the nail → this needs prompt evaluation. Read more at black nails.
Diagnosing brittle nails
Diagnosing brittle nails relies mainly on history and physical examination, and blood tests are not needed in every case. What a dermatologist assesses includes:
History of exposure to water and chemicals: occupation, housework, how many times a day the hands are washed, and glove use.
History of nail treatments: how often gel or acrylic nails are done, how they are removed, and which nail coatings are used.
Medication and medical history: oral retinoids, chemotherapy, thyroid disease, kidney disease and anemia.
Examination of every fingernail and toenail: including the cuticle and the skin elsewhere, to look for signs of psoriasis or irritant contact dermatitis.
Examining the nails with a magnifying scope (onychoscopy): this helps tell apart peeling in layers, vertical ridges, nail pits and pigment under the nail in more detail than the naked eye.
Testing for fungus: nail scrapings sent for KOH and culture, or nail clippings stained with PAS, when fungus is suspected. This should always be done before starting oral medication.
Blood tests when indicated: a complete blood count and ferritin when anemia is suspected, thyroid hormones when symptoms fit, and kidney or liver function when specific pale-nail patterns are seen.
How to care for and treat brittle nails
Brittle nails respond well to treatment in most patients, but it has to be done consistently and given time, because what you see today is nail that was produced many months ago.
1. Reduce contact with water and chemicals — the most important step
Wear rubber gloves over thin cotton gloves every time you wash dishes, do laundry or clean. The inner cotton glove absorbs sweat so that the hands do not become clammy, which is a problem that makes many people stop wearing gloves halfway. Avoid soaking the hands in water for long periods and dry the hands every time.
2. Restore moisture to the nail plate
Apply a moisturizer containing urea, lactic acid or petrolatum to the nail plate and the skin around the nail. The best times are after washing the hands while the nail is still slightly damp, and before bed. You can reapply several times a day as needed. This is the measure with the most weight in treating brittle nails.
3. Trim your nails the right way
Cut nails short enough to reduce the leverage on the nail tip. Use a fine-grit file and file in one direction only, not back and forth, because filing back and forth makes the layers at the tip separate even more. Do not cut or push back the cuticle, because it is the natural protective barrier for the nail base.
4. What to avoid
Nail polish remover containing acetone. Choose an acetone-free type and use it as little as possible.
Nail hardeners containing formaldehyde. Used continuously, they make nails more brittle.
Peeling or prying off gel nails yourself. Have them removed by a skilled technician, or leave a gap between sessions to let the nails rest.
Using nails as tools, such as peeling off stickers, opening cans or pressing buttons.
5. Supplements and medication — when they have a role
Nutrient supplementation helps only when a true deficiency has been found, for example iron when iron deficiency is confirmed, or treatment of thyroid disease when an abnormality is found. Taking supplements without an indication does not improve the nails and may interfere with other test results. When a nail disease is also present, such as fungus or psoriasis, treating the underlying disease is what brings the nails back to health, not nail-care products.
How long does it take: a fingernail takes about 4–6 months to grow out completely, and a toenail about 12–18 months. So follow the plan consistently and assess the results after at least 3–6 months before deciding whether it is working.
How to prevent brittle nails
Protect before contact: make it a habit to wear gloves every time you do wet work or work involving chemicals.
Make moisturizer a routine: keep a tube of cream next to the sink and next to the bed so you can apply it without effort.
Avoid habits that harm the nails: biting nails, picking at nails, pushing back the cuticle, or using nails as tools.
Rest the nails periodically: if you regularly have gel or acrylic nails done, leave breaks so the nails can recover.
Look after your overall health: eat a balanced diet, drink enough water, and have an annual health check to screen for systemic diseases that may affect the nails.
When to see a dermatologist
You have cared for them the right way for 3 months but they have not improved, or they are getting worse
The nail changes color, thickens, separates from the nail bed, or has debris under it
Only one finger is affected, or it looks clearly different from the other fingers
There is a brown or black band running lengthwise, especially if it keeps widening
Swelling, redness, pain or pus around the nail
Systemic symptoms such as hair loss, fatigue, weight change, palpitations or feeling cold all the time
Frequently asked questions
What are brittle nails? Brittle nails (Brittle Nails) are a condition in which the nail plate loses its flexibility, so it cracks, breaks or peels in layers easily. There are 2 main patterns: Onychoschizia, in which the nail peels in horizontal layers at the tip, and Onychorrhexis, in which the nail splits into longitudinal grooves.
Which nutrient deficiency causes brittle nails? In people who eat normally, brittle nails are usually not caused by a nutrient deficiency. The most common causes are repeated wetting and drying, cleaning products, acetone and increasing age. If there is a true deficiency, iron causes spoon-shaped nails (koilonychia) and zinc causes horizontal grooves, which look very different from ordinary brittle nails.
Which vitamin makes nails strong? No vitamin has yet been proven to make the nails of people who are not deficient any stronger. Biotin has some supporting studies, but they are small and mostly without a control group. High-dose biotin also interferes with some blood tests, such as thyroid hormones and troponin, so always tell your doctor before a blood draw.
What causes pale nails? The most common cause is cold weather or temporary constriction of blood vessels, which is not dangerous. But if all fingers stay pale, it may be caused by anemia, chronic liver disease (Terry’s nails), chronic kidney disease (half-and-half nails) or low blood albumin. See a doctor for blood tests to find the cause.
How do brittle nails differ from wavy nails? Brittle nails are nails that break or peel in layers, and the problem lies in the adhesion between keratin layers. Wavy nails have an uneven surface with ridges or raised grooves running across it, which result from uneven nail production by the nail base. The two conditions often occur together, especially in older adults.
Does calcium make nails strong, and do white spots on nails mean calcium deficiency? Neither. Nails are made of keratin, which is a protein, not calcium, so taking extra calcium does not make nails harder. White spots on nails almost always come from minor knocks to the nail base several weeks earlier, and then move out as the nail grows.
How long does it take to see results when treating brittle nails? A fingernail takes about 4–6 months to grow out completely, and a toenail about 12–18 months, so follow the plan consistently and assess the results after at least 3–6 months.
When should brittle nails be seen by a doctor? See a dermatologist when correct self-care for 3 months has not helped, the nails change color or thicken, only one finger is affected, there is a brown or black band running lengthwise, the area around the nail is swollen and red with pus, or there are systemic symptoms such as hair loss, fatigue or palpitations.
Most brittle nails can be managed with changes in habits and consistent moisturizing. But if the problem is chronic, has features that do not fit ordinary brittle nails, or a systemic disease is suspected, you should get a proper diagnosis. You can consult a dermatologist at Siam Dermatology, tel. +66 61 448 7000 or LINE @siamderm.
If you want to compare your nail symptoms with other nail conditions, see the full symptom comparison table in the Nail disease guide: telling apart abnormal nail symptoms
References
DermNet NZ. Nail disorders. https://dermnetnz.org/topics/nail-disorders
DermNet NZ. Nail terminology. https://dermnetnz.org/topics/nail-terminology
American Academy of Dermatology. Tips for healthy nails. https://www.aad.org/public/everyday-care/nail-care-secrets/basics/healthy-nail-tips
U.S. Food and Drug Administration. Biotin Interference with Troponin Lab Tests — Assays Subject to Biotin Interference. https://www.fda.gov/medical-devices/in-vitro-diagnostics/biotin-interference-troponin-lab-tests-assays-subject-biotin-interference
van de Kerkhof PCM, Pasch MC, Scher RK, et al. Brittle nail syndrome: a pathogenesis-based approach with a proposed grading system. J Am Acad Dermatol. 2005;53(4):644-651.
Bolognia JL, Schaffer JV, Cerroni L, eds. Dermatology. 4th ed. Elsevier; 2018. Nail Disorders chapter.
UpToDate. Overview of nail disorders. https://www.uptodate.com/contents/overview-of-nail-disorders
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed July 30, 2026
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