What brittle nails and ridges can tell you
Brittle nails and surface ridges are common nail changes that can develop gradually or appear after an illness, medication change, or repeated exposure to water and chemicals.
This article explains what causes brittle nails and ridges, how to tell the difference between harmless changes and possible medical concerns, and when to seek evaluation.
What are brittle nails and ridges?
Brittle nails are nails that split, peel, crack, or break easily.
Ridges are raised or indented lines that run along the nail plate; they may be vertical, running from the cuticle to the tip, or horizontal, crossing the nail.
These changes affect the nail plate, the hard keratin structure produced by the nail matrix.
Because nails grow slowly, visible changes often reflect exposures or health issues that happened weeks or months earlier.
What causes brittle nails and ridges?
The answer is usually multifactorial.
In many people, nail fragility comes from a combination of repeated wet-dry cycles, age-related changes, and minor trauma.
In others, brittle nails and ridges point to iron deficiency, thyroid disease, inflammatory skin disorders, or a side effect of medication.
Vertical ridges are often benign, especially with aging.
Horizontal ridges, however, can sometimes suggest a temporary interruption in nail growth, such as from illness, severe stress on the body, or injury to the nail matrix.
Common nonmedical causes
Frequent hand washing and wet-dry cycles
Water exposure is one of the most common reasons nails become brittle.
Repeated soaking and drying can make nails swell and contract, weakening the nail plate over time.
- Frequent handwashing
- Long baths or showers
- Dishwashing without gloves
- Swimming, especially in chlorinated pools
Harsh chemicals and cosmetic products
Household cleaners, acetone-based nail polish removers, gels, acrylics, and certain nail hardeners can dry or damage nails.
Overuse of nail products may also thin the surrounding skin, making nails more prone to breakage.
Mechanical trauma
Typing, nail biting, picking at polish, and using nails as tools can create repeated micro-injuries.
Over time, this can lead to splitting, peeling, or ridging.
Aging
As people age, nail growth slows and the nail plate may become drier and more uneven.
Mild longitudinal ridging is common in older adults and is often considered a normal age-related change.
Medical conditions linked to brittle nails and ridges
Iron deficiency and anemia
Iron deficiency is a well-known contributor to brittle nails.
In some cases, nails may also become thin, spoon-shaped, or develop ridging.
If brittle nails are accompanied by fatigue, pale skin, shortness of breath, or hair shedding, iron studies may be appropriate.
Thyroid disorders
Both hypothyroidism and hyperthyroidism can affect nail growth and quality.
Nails may become dry, brittle, or lifted from the nail bed, and ridges can appear as growth patterns change.
Psoriasis
Nail psoriasis can cause pitting, thickening, discoloration, crumbling, and horizontal or vertical ridges.
It commonly occurs in people who also have skin plaques or joint symptoms.
Eczema and dermatitis
Chronic hand eczema and contact dermatitis can disrupt the nail matrix and surrounding skin.
This often leads to roughness, splitting, and persistent ridging, especially if the hands are frequently inflamed or scratched.
Fungal nail infection
Onychomycosis can make nails brittle, discolored, thick, and distorted.
While fungus more often causes thickening than ridges, it can still contribute to irregular nail texture and breakage.
Systemic illness and nutritional stress
Severe illness, major surgery, high fever, or significant physiologic stress can temporarily interrupt nail growth.
This may result in Beau’s lines, which are transverse ridges or grooves that move outward as the nail grows.
Nutritional factors that may play a role
Nails need adequate protein, iron, zinc, biotin, and overall calories to grow normally.
A restrictive diet, malabsorption, eating disorder, or prolonged poor intake can affect nail strength.
- Protein: Nail keratin is protein-based, so low protein intake can weaken nail structure.
- Iron: Low iron stores are a common cause of brittle, weak nails.
- Zinc: Deficiency can impair nail growth and recovery.
- Biotin: True deficiency is uncommon, but some clinicians consider it in selected cases.
Supplements are most useful when a deficiency is present or strongly suspected.
Taking high-dose supplements without a diagnosis may not improve nails and can interfere with lab testing or other treatments.
Which ridge patterns matter most?
Vertical ridges
Vertical ridges, also called longitudinal ridges, are the most common nail ridge pattern.
They usually run from the cuticle toward the tip and often become more noticeable with age, dryness, or mild trauma.
Horizontal ridges
Horizontal ridges, also called transverse lines or Beau’s lines, deserve closer attention because they may reflect a temporary pause in nail formation.
They can follow fever, significant illness, chemotherapy, trauma, or severe metabolic stress.
Single-nail changes
If only one nail is affected, a local cause is more likely, such as injury, chronic pressure, or a growth on or under the nail.
Changes in a single nail are more likely to warrant a clinical exam than symmetrical changes across several nails.
When to get checked by a clinician
Consider medical evaluation if brittle nails and ridges appear suddenly, worsen quickly, or come with other symptoms.
A primary care clinician or dermatologist may review medications, diet, thyroid status, iron studies, and signs of skin disease.
- Nails are breaking rapidly despite gentle care
- Ridges are new, deep, or horizontal
- There is pain, redness, swelling, or drainage
- Nails are lifting, thickening, or changing color
- You also have fatigue, weight changes, hair loss, or skin symptoms
- Only one nail is affected and the change persists
How clinicians evaluate brittle nails and ridges
Evaluation usually begins with a history and physical exam.
A clinician may ask about water exposure, nail cosmetics, diet, recent illness, autoimmune disease, and medications such as retinoids, chemotherapy agents, or some antihypertensives.
Depending on the findings, testing may include complete blood count, ferritin, thyroid-stimulating hormone, and sometimes fungal testing or biopsy if the diagnosis is unclear.
The goal is to identify an underlying cause rather than treating the nail appearance alone.
Practical ways to protect brittle nails
Most brittle nails improve when the underlying trigger is reduced.
These habits can help support nail strength while the nail grows out:
- Wear gloves for dishwashing, cleaning, and prolonged water exposure
- Use a fragrance-free hand moisturizer after washing
- Choose acetone-free removers when possible
- Avoid cutting cuticles or aggressively buffing nails
- Keep nails trimmed and filed in one direction
- Limit acrylics, gels, and repeated polish changes if nails are fragile
- Eat a balanced diet with adequate protein and iron-rich foods
If a medical condition is responsible, treating the condition often improves nail quality slowly over several months.
Because nails grow gradually, even a successful treatment plan may take time before visible changes appear.
What causes brittle nails and ridges in children or younger adults?
In younger people, nail changes are less likely to be explained by aging and more likely to involve trauma, eczema, repetitive wetting, or nutritional issues.
Psoriasis, thyroid disease, and iron deficiency can also occur in younger adults, so persistent nail changes should not be dismissed as cosmetic.
How to tell when nail changes are harmless
Mild vertical ridging in otherwise healthy nails is often normal, especially if it develops gradually and affects several nails equally.
Dryness, occasional splitting, and slower nail growth can also occur without an underlying disease.
What makes nail changes more concerning is a clear change from baseline, accompanying symptoms, or a pattern that suggests interruption of nail growth.
In those cases, the question is not just what causes brittle nails and ridges, but what is disrupting the body’s normal nail production.