SymptomSkin, hair & nails
Irregular-Appearing Nails: What Changes in Nail Shape and Surface Mean
Irregular-appearing nails are nails whose shape, surface or attachment has changed: pits, dents, grooves, a spoon or club shape, thickening, splitting or lifting from the nail bed. Most changes come from injury, nail fungus, eczema or psoriasis, or daily wear such as frequent hand washing. Some patterns are clues to body-wide conditions, such as spoon nails with iron deficiency and clubbing with lung or heart disease. A new dark streak or a nail change with a growing lump should be checked promptly.
Also called: Nail abnormalities, nail deformities, abnormal nails, nail changes
At a glance
- What it is
- Any change in nail shape, surface texture, thickness or attachment.
- Most common causes
- Injury, nail fungus, psoriasis, eczema, frequent wetting and drying, and aging.
- Clues to body-wide disease
- Spoon nails (iron deficiency), clubbing (lung, heart or liver disease), Beau's lines (a past serious illness or chemotherapy).
- How serious
- Usually cosmetic or minor, but a new dark band, a nail destroyed by a growing lump, or sudden clubbing needs a doctor.
- Diagnosis
- Examination, nail clipping tests for fungus, blood tests and sometimes a nail biopsy.
When to get help
See a doctor within a day or two
- A new or widening dark brown or black streak in one nail, especially if the color spreads onto the surrounding skin
- A lump under or beside the nail that is growing, bleeding or lifting the nail
- A painful, red, swollen nail fold with pus, or a red streak up the finger
- Fingertips that become clubbed over weeks, especially with cough, breathlessness or weight loss
Book a routine appointment
- Nails that are pitted, crumbling, thickened or lifting for more than a few weeks
- Spoon-shaped nails, especially with tiredness or heavy periods
- Grooves across several nails at once
- Nail changes along with a scaly rash, joint pain or hair loss
Usually safe to manage at home
- A single nail damaged by a known injury and growing out normally
- Mild peeling or splitting of fingernails from frequent washing or cleaning products
How to describe your nail change
Fingernails grow about 3 mm a month and take about 6 months to replace completely. Toenails take 12 to 18 months. That slow growth means a nail records events: a line in the middle of a fingernail usually reflects something that happened about 3 months earlier.
Note whether the change affects one nail or many. A single nail usually points to a local cause (injury, fungus, a growth). Many or all nails at once point to a skin disease or a body-wide condition.
Common nail shape and surface changes
| Nail change | What it looks like | Common causes |
|---|---|---|
| Pitting | Small dents like a thimble | Psoriasis, eczema, alopecia areata |
| Beau's lines | Deep grooves across the nail | Serious illness, high fever, chemotherapy, injury |
| Spoon nails (koilonychia) | Thin, scooped-out nail that can hold a drop of water | Iron deficiency, normal in young children |
| Clubbing | Bulbous fingertips, nail curves down, loss of the angle at the nail base | Lung disease, heart disease, liver disease, IBD |
| Onycholysis | Nail lifts from the bed, white or yellow underneath | Fungus, psoriasis, injury, thyroid disease, harsh chemicals |
| Thickening | Thick, hard, yellowish, often crumbly | Fungus, aging, poor circulation, repeated trauma |
| Splitting and peeling | Layers separate at the tip | Frequent wetting, detergents, aging |
| Vertical ridges | Fine lines from base to tip | Aging (harmless), lichen planus when severe |
| Median canal | A split or groove down the middle | Habitual picking of the cuticle |
| Rough, sandpaper nails (trachyonychia) | All nails rough and dull | Alopecia areata, lichen planus, psoriasis |
For color changes, see nail discoloration. For lines from base to tip, see nail ridges.
Causes of irregular nails
Injury and habits
Crushing a finger, stubbing a toe, tight shoes and long-distance running damage the nail matrix (the growth area under the cuticle) and cause dents, lifting, thickening or a black nail from bleeding underneath. Biting, picking and pushing back cuticles cause wavy surfaces and grooves. Damage to the matrix can make a change permanent.
Fungal infection
Fungal nail infection is the most common cause of thickened, discolored, crumbly toenails. It often starts at the tip or edge and spreads back. Athlete's foot is frequently present too.
Psoriasis and other skin conditions
Up to half of people with psoriasis, and most with psoriatic arthritis, have nail changes: pits, lifting with a yellow-pink "oil drop" spot, and crumbling. See nail psoriasis. Lichen planus can thin the nail, deepen ridges, and in severe cases destroy it. Eczema around the nail causes ridging and pitting.
Body-wide conditions
- Iron deficiency: spoon-shaped, brittle nails. Check for iron deficiency anemia.
- Lung and heart disease: clubbing develops in lung cancer, bronchiectasis, pulmonary fibrosis, cystic fibrosis and some congenital heart disease.
- Thyroid disease: onycholysis in overactive thyroid. Slow-growing, brittle nails in underactive thyroid.
- Serious illness or chemotherapy: Beau's lines across all nails, sometimes shedding of nails a few months later.
- Kidney and liver disease: changes in the color of the nail bed, such as half-and-half nails or white nails.
Infection around the nail
Paronychia, an infection of the nail fold, can cause ridges and a wavy nail if it becomes long-lasting, often in people whose hands are often wet.
Tumors
Most nail lumps are harmless (warts, cysts, glomus tumors). Rarely, melanoma or squamous cell carcinoma affects the nail unit. Warning signs are a dark band that widens, a band with irregular color, pigment on the skin around the nail, and a nail that is destroyed or bleeding.
How doctors find the cause
A doctor or dermatologist will look at all 20 nails, the skin, scalp and joints. They ask about injuries, nail care, work with water or chemicals, medicines and past illness. Tests may include:
- nail clippings sent to the lab for fungal testing (needed before long courses of antifungal tablets)
- blood tests such as a complete blood count, ferritin, thyroid function, and kidney and liver tests
- a chest X-ray or lung tests for new clubbing
- a nail biopsy for a suspicious streak or persistent unexplained change
Treatment and nail care
Treatment depends on the cause. Fungal nails need antifungal lacquers or tablets. Psoriasis may improve with steroid creams or injections into the nail fold, or with medicines that treat the whole body. Iron deficiency is treated with iron and investigation of the cause.
Care that helps most irregular nails:
- Keep nails short and file them in one direction.
- Wear cotton-lined gloves for wet work and cleaning.
- Moisturize nails and cuticles after washing.
- Do not cut, push back or pick at cuticles.
- Wear shoes with enough toe room.
- Avoid nail polish removers containing acetone and limit gel or acrylic nails, which can thin the nail plate.
Damaged nails take months to grow out: about 6 months for fingernails and a year or more for toenails.
Frequently asked questions
What do irregular nails mean?
Most irregular nails are caused by injury, nail fungus, psoriasis, eczema or frequent wetting. Some patterns are clues to health conditions: spoon nails suggest low iron, clubbing suggests lung or heart disease, and grooves across all nails suggest a past serious illness.
What does it mean when nails become pitted?
Small pits are most often caused by psoriasis, especially nail psoriasis. They can also occur with eczema and alopecia areata. A few shallow pits can be normal. If pits come with lifting or crumbling of the nails or joint pain, see a doctor.
Can vitamin deficiency cause nail changes?
Iron deficiency is the best-established cause, producing thin, spoon-shaped nails. Low zinc, protein deficiency and, rarely, biotin deficiency can cause brittle or slow-growing nails. Biotin supplements can interfere with thyroid and heart blood tests, so tell your doctor if you take them.
When should I worry about a nail change?
See a doctor promptly for a new dark streak in one nail, especially if it widens or the color spreads onto the skin, a growing lump under the nail, signs of infection, or new clubbing of the fingertips. Persistent changes in many nails also deserve an assessment.
How long does a damaged nail take to grow out?
Fingernails grow out completely in about 4 to 6 months. Toenails take 12 to 18 months. If the nail matrix under the cuticle was badly damaged, the nail may stay permanently irregular.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Nail changes a dermatologist should examine
- MedlinePlus: Nail abnormalities
- NHS: Nail problems
- American Academy of Family Physicians: Nail Abnormalities: Clues to Systemic Disease
- Mayo Clinic: Fingernails: Do's and don'ts for healthy nails