Nail Disorders That Shouldn't Be Ignored

Changes in the fingernails or toenails are often caused by minor injury, frequent water exposure, nail cosmetics, or normal aging. However, persistent changes in nail color, shape, thickness, texture, or growth can also indicate infection, inflammatory skin disease, medication effects, or an underlying medical condition.

A nail problem should be evaluated when it appears suddenly, affects only one nail, causes pain or swelling, continues to worsen, or does not improve with basic care.

A New or Changing Dark Streak

Brown or black lines can develop for several reasons, including injury, medication, benign pigmentation, or natural variation in people with darker skin tones.

However, a new or changing dark streak in one nail should be examined because melanoma can rarely develop beneath or around the nail.

Warning signs may include:

• A band that becomes wider or darker
• Irregular color or borders
• Pigment spreading onto the surrounding skin
• Nail splitting or distortion
• Bleeding beneath the nail
• A persistent mark without a clear injury

Not every dark streak is cancer, but the American Academy of Dermatology recommends evaluation of a new or changing pigmented band because nail melanoma is easier to treat when detected early.

Thick, Yellow, or Crumbling Nails

Thickened, discolored, brittle nails are commonly associated with fungal nail infection, also called onychomycosis.

Possible signs include:

• Yellow, white, brown, or orange discoloration
• Crumbling edges
• Nail thickening
• Buildup beneath the nail
• Separation from the nail bed
• Cracking or splitting
• Unpleasant odor
• Discomfort while wearing shoes

A fungal infection cannot always be diagnosed from appearance alone. Trauma, psoriasis, aging-related changes, and other nail diseases can look similar. Dermatologists may collect nail clippings or material from beneath the nail for laboratory testing before recommending long-term antifungal treatment.

Nail Pitting or Separation

Small dents in the nail surface are known as nail pits. They may occur with psoriasis, alopecia areata, eczema, or other inflammatory conditions.

Psoriasis may also cause:

• Nail thickening
• Yellow-brown discoloration
• Crumbling
• Separation from the nail bed
• Buildup beneath the nail
• Irregular nail growth

Patients with nail psoriasis should mention joint pain, morning stiffness, swollen fingers or toes, and heel pain because psoriasis may also be associated with inflammatory arthritis.

Nail separation can also result from trauma, fungal infection, thyroid disease, medication, or repeated exposure to water and chemicals, so diagnosis should not be based on one sign alone.

Painful Redness Around the Nail

Redness, swelling, tenderness, or pus around the nail may indicate paronychia, an infection or inflammation of the surrounding nail fold.

Possible triggers include:

• Nail biting
• Picking at cuticles
• Manicures
• Ingrown nails
• Repeated handwashing
• Wet work
• Small cuts
• Artificial nails
• Irritating chemicals

Acute infection may develop quickly and become painful. Chronic inflammation may cause repeated swelling, loss of the cuticle, and irregular nail growth.

Prompt evaluation is particularly important when redness is spreading, pus is present, pain is increasing, or the patient has diabetes, poor circulation, or reduced immunity.

Clubbing or Increased Nail Curvature

Clubbing causes the fingertips to enlarge and the nails to curve downward. The nail may also feel unusually soft or spongy when pressed.

Some people naturally have curved nails, but newly developing clubbing can occasionally be associated with medical conditions affecting the lungs, heart, liver, or digestive system.

The change usually affects several nails rather than one isolated finger. New clubbing should be medically evaluated rather than treated as a cosmetic nail concern.

Deep Horizontal Grooves

Horizontal depressions across the nail are often called Beau lines. They occur when nail growth is temporarily interrupted.

Possible causes include:

• Significant illness
• High fever
• Major physical stress
• Injury to the nail matrix
• Severe inflammation around the nail
• Certain medications
• Nutritional or systemic illness

One groove affecting a single nail may follow local trauma. Similar lines appearing across several nails may indicate that nail growth was disrupted throughout the body.

Because nails grow slowly, the line may become visible weeks after the triggering event.

Spoon-Shaped or Unusually Brittle Nails

Thin nails that curve upward at the edges are sometimes described as spoon-shaped nails.

Possible contributing factors include:

• Iron deficiency
• Repeated chemical exposure
• Trauma
• Certain inflammatory conditions
• Natural nail shape

Brittle nails are common and may result from frequent wetting and drying, nail-polish remover, aging, or repeated manicures. However, widespread or sudden changes may justify evaluation for nutritional, thyroid, or other medical factors.

Supplements should not be started automatically because brittle nails do not always indicate a vitamin deficiency.

Green, White, or Unusual Nail Color

Nail color changes can occur because of staining, infection, trauma, medication, or medical illness.

Examples include:

• Green discoloration associated with certain bacterial infections
• White patches after minor trauma
• Yellow discoloration from fungus or nail products
• Red or purple color from bleeding beneath the nail
• Brown pigmentation from medication or natural melanin
• Pale or widespread white nails associated with selected systemic conditions

Color alone is rarely enough to identify the cause. The number of nails affected, speed of change, surrounding skin, medication history, and presence of pain all help guide diagnosis. Nail changes can occasionally reflect medical conditions beyond the nail itself.

An Ingrown Nail That Keeps Returning

An ingrown nail occurs when the nail edge grows into the surrounding skin, most commonly on the big toe.

Symptoms may include:

• Pain along the nail edge
• Redness
• Swelling
• Bleeding
• Pus
• Overgrown surrounding tissue

Contributing factors include cutting the nail too short, rounding the corners, tight footwear, trauma, and naturally curved nails.

Mild cases may improve with appropriate nail care, but repeated infection, severe pain, or excess tissue may require medical or surgical treatment.

A Growth or Wound That Does Not Heal

A persistent lump, ulcer, bleeding area, or wart-like growth near or beneath the nail should be examined.

Possible causes include:

• Warts
• Cysts
• Chronic infection
• Benign nail tumors
• Squamous cell carcinoma
• Nail-unit melanoma

Some tumors can distort or destroy the nail plate and may initially be mistaken for a fungal infection or injury. Persistent changes in one nail that do not respond to treatment should therefore be reassessed rather than repeatedly treated without confirmation.

How Dermatologists Evaluate Nail Disorders

A dermatologist may examine:

• All fingernails and toenails
• Nail color and thickness
• Nail attachment
• Surrounding skin and cuticles
• Scalp and other skin areas
• Hair and joint symptoms
• Medication and medical history
• Recent injury or cosmetic procedures

Additional tests may include:

• Nail clippings
• Fungal microscopy or culture
• Bacterial testing
• Blood tests
• Dermoscopic examination
• Nail-matrix or nail-bed biopsy

A biopsy may be recommended when a tumor, melanoma, inflammatory nail disease, or another uncertain condition is suspected.

Questions to Ask During Consultation

Consider asking:

• Is this caused by fungus, trauma, or inflammation?
• Do I need nail clippings or laboratory testing?
• Could the change be related to psoriasis?
• Is the dark streak concerning?
• Could medication be affecting my nails?
• Do I need blood tests or a biopsy?
• How long will normal nail growth take?
• Which changes require urgent follow-up?

Do Not Ignore Persistent or Unexplained Nail Changes

Many nail changes are harmless, but problems that are new, painful, progressive, limited to one nail, or resistant to treatment deserve medical evaluation.

A darkening band, persistent nail destruction, spreading infection, clubbing, unexplained grooves, or a non-healing growth may provide important information about the nail or general health.

Early diagnosis helps distinguish common conditions such as fungal infection or psoriasis from less common but more serious disorders that require prompt treatment.