SymptomSkin, hair & nails
Nail Problems: Causes and What Nail Changes Mean
Nail problems are changes in the color, shape, thickness or texture of fingernails or toenails, or pain and swelling around them. Most are caused by fungal infection, injury, psoriasis, aging or frequent wetting and drying. Some nail changes reflect a body-wide condition, such as clubbing with lung disease or spoon-shaped nails with iron deficiency. A new dark streak in a nail, especially a widening one or one that spreads onto the skin, should be checked for melanoma.
Also called: Nail abnormalities, nail changes, nail disorders, nail dystrophy
At a glance
- Most common causes
- Fungal infection, injury, psoriasis, aging, wet work, harsh nail products.
- Common changes
- Thickening, yellowing, brittleness, ridges, pitting, lifting from the nail bed.
- Signs of other illness
- Clubbing, spoon nails, white nails, splinter hemorrhages, Beau's lines.
- Red flag
- A new or changing dark streak, or pigment spreading onto the skin.
- Diagnosis
- Examination, nail clippings for fungus, sometimes blood tests or biopsy.
When to get help
See a doctor within a day or two
- Red, hot, throbbing swelling beside a nail with pus, or redness spreading up the finger
- A crushed nail with a painful blood blister under more than about half of the nail, or a possible fracture
- Any nail infection or ulcer on the foot in someone with diabetes or poor circulation
Book a routine appointment
- A new brown or black streak in a nail, especially one that widens, has blurred edges or extends onto the cuticle
- A nail that lifts, thickens or bleeds without injury, especially just one nail
- New clubbing (bulbous fingertips with curved nails)
- Spoon-shaped nails, white nails or many nail changes at once with tiredness or other symptoms
- Thick, yellow nails that bother you or are spreading
Usually safe to manage at home
- Mildly brittle or peeling nails from frequent handwashing or nail polish remover
- Vertical ridges that develop slowly with age
- Small white spots after minor knocks
How nails grow, and why changes take time
Nails are made of hard keratin produced by the nail matrix under the cuticle. Fingernails grow about 3 mm a month and take around 6 months to grow out fully. Toenails grow much more slowly and take 12 to 18 months. That means a nail change often reflects something that happened weeks or months earlier, and treatment results take months to show.
Common nail problems
Fungal nail infection
Onychomycosis is the most common nail disease, mostly affecting toenails. Nails become thick, yellow, white or brown, crumbly and lifted, often starting at the tip or side. It is more common with age, athlete's foot, diabetes, sweaty feet and communal showers.
Nail psoriasis
About half of people with psoriasis have nail changes, and up to 80 percent of those with psoriatic arthritis. Signs of nail psoriasis include small pits, "oil drop" yellow-pink patches, lifting of the nail (onycholysis), thickening and crumbling. It can look like fungus, and the two can occur together.
Brittle, splitting and peeling nails
Brittle nails are very common, especially in women and older adults. Causes include repeated wetting and drying, dishwashing, cleaning products, nail polish remover, gel and acrylic nails and aging. Rarely, low iron or an underactive thyroid contributes.
Lifting of the nail (onycholysis)
The nail separates from the bed and looks white or yellow. Causes include injury, long nails used as tools, overzealous cleaning under the nail, fungal infection, psoriasis, reactions to nail products, an overactive thyroid and some medicines that react with sunlight.
Infections around the nail
- Acute paronychia: sudden red, painful, swollen skin at the nail fold, often after nail biting, a hangnail or a manicure. Pus may collect.
- Chronic paronychia: a swollen, tender nail fold with a missing cuticle, lasting weeks, in people whose hands are often wet.
Ingrown toenails
The edge of the nail grows into the skin, usually on the big toe, causing pain, redness and sometimes infection. Cutting nails curved or too short and tight shoes are common causes.
Injury
- Subungual hematoma: a dark red or black blood blister under the nail after a crush.
- White spots (leukonychia): usually from minor knocks, not calcium deficiency.
- Damage from repeated trauma, for example runners' toenails, causing thickening and loss of the nail.
Nail changes that can point to other conditions
| Nail change | What it looks like | Possible causes |
|---|---|---|
| Clubbing | Bulbous fingertips, nail curves over the tip | Lung disease, lung cancer, heart disease, liver and bowel disease |
| Spoon nails (koilonychia) | Thin, scooped-out nails | Iron deficiency anemia |
| Beau's lines | Horizontal grooves across the nail | Serious illness, high fever, chemotherapy months earlier |
| Pitting | Small dents | Psoriasis, alopecia areata, eczema |
| Terry's nails | Mostly white with a pink band at the tip | Liver cirrhosis, heart failure, kidney disease, aging |
| Half-and-half nails | White near the base, brown at the tip | Chronic kidney disease |
| Splinter hemorrhages | Thin red-brown lines | Injury (common), rarely endocarditis |
| Yellow nails | Thick, slow-growing yellow nails | Fungus, smoking, rarely yellow nail syndrome |
| Dark streak (melanonychia) | Brown or black vertical band | Normal in darker skin, moles, medicines, melanoma |
Dark streaks and melanoma
Brown vertical lines in several nails are common and harmless in people with darker skin. A single new or changing streak needs a dermatologist's assessment, especially if it is wider than 3 mm, darkening, irregular, or if pigment spreads onto the cuticle or skin (Hutchinson's sign). These can be signs of nail melanoma, which is often diagnosed late.
Vertical ridges
Fine lengthwise nail ridges are a normal part of aging. A single deep ridge, or a split that runs the length of the nail, can come from a growth pressing on the matrix and should be checked.
How nail problems are diagnosed
A doctor or dermatologist looks at all the nails and the skin, asks about injury, nail care, occupation, medicines and other health problems, and may:
- send nail clippings to a lab to confirm fungus before long treatment
- order blood tests for iron, thyroid function, kidney or liver disease
- examine pigmented nails with a dermatoscope
- perform a nail biopsy for a suspicious streak, lump or unexplained change
Treatment
- Fungal infection: oral antifungal tablets (most effective, but need monitoring) or medicated nail lacquers for mild cases. Clearing takes 6 to 18 months as the nail grows out.
- Nail psoriasis: steroid and vitamin D creams, steroid injections into the nail fold, and systemic or biologic medicines for severe disease.
- Paronychia: warm soaks, antibiotics, and drainage of an abscess. Chronic paronychia needs keeping hands dry and anti-inflammatory creams.
- Ingrown toenail: soaking, lifting the edge, and minor surgery to remove the edge of the nail if it keeps recurring.
- Brittle nails: wear gloves for wet work, moisturize nails and cuticles, use acetone-free remover and limit gel and acrylic nails. Biotin has limited evidence and can interfere with blood test results.
- Underlying conditions: iron replacement, thyroid treatment and so on.
Healthy nail habits
- Keep nails short, and cut toenails straight across.
- Do not bite nails or pick cuticles.
- Wear flip-flops in communal showers, and dry between the toes.
- Use clean tools, and avoid cutting cuticles at salons.
Frequently asked questions
What do my nails say about my health?
Most nail changes come from local causes like fungus, injury, psoriasis or aging. Some signal other conditions: spoon nails can mean iron deficiency, clubbing can mean lung or heart disease, and white nails can mean liver or kidney disease. A doctor can tell which changes need tests.
Why are my toenails thick and yellow?
The most common cause is a fungal infection, especially if the nail is also crumbly and lifting. Psoriasis, repeated injury from shoes or running, and aging can cause similar changes. A lab test of nail clippings confirms fungus before treatment.
What causes pitting in nails?
Small pits in the nail surface are most often caused by psoriasis. They also occur with eczema and alopecia areata, a condition that causes patchy hair loss. Pitting with joint pain may suggest psoriatic arthritis.
When should I worry about a dark line on my nail?
See a dermatologist for a single new or changing dark line, especially if it is wider than 3 mm, getting darker or wider, has blurred edges, or pigment spreads onto the surrounding skin. These can be signs of melanoma. Several thin lines in darker skin are usually normal.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Nail fungus and nail changes
- American Academy of Dermatology: Nail psoriasis
- MedlinePlus: Nail abnormalities
- Mayo Clinic: Fingernails, do's and don'ts for healthy nails
- American Academy of Family Physicians: Nail abnormalities, clues to systemic disease