The Health Warnings Hidden in Your Fingernails

If your eyes are a window to your soul, your nails can be a key into your well-being.

“Your nail health is a very good reflection of your overall health,” says dermatologist Christine Poblete-Lopez, MD. “Many things can occur in the nails that can signify systemic or skin problems.”

Pay attention to anything on or around your fingernails or toenails that suddenly appear different such as color, texture or shape. This may be a sign of things like a fungal infection, vitamin deficiency, arthritis, psoriasis or melanoma.

Health conditions that can affect your nails

Healthy nails tend to have a pink nail bed and appear smooth and shiny. But in some cases, your nails may look different.

You may notice discoloration, tiny dents, longitudinal strips or ridges, brittleness, splitting or white spots. So, what do these signs mean? Your nail changes may be related to the following reasons:

Nail fungus

If your toenails are a yellow shade, there’s a chance you may have a fungal infection. Over time your nails may also become thick and have white spots (leukonychia) or streaks. It’s not as common, but you can get a fungal infection in your fingernails. A crack or cut in your toe can be the perfect way for fungi to get between your nail and the tissue right under your nail, known as your nail bed.

Nail infection

If you have cut on your cuticles or nail folds (where your nail and skin come together), bacteria can get in your nailfolds (paronychia). This can cause inflammation, pain and swelling around your nail but can also result in ridges or waves on the nail plate. In some cases, your nails can turn yellow or green and become brittle and dry.

Nail injury

If you’ve ever stubbed your toe or wear shoes that are too tight, you may notice that your toenail turns a darker shade (think purple, red, brown or black). A nail injury or trauma can cause a bruise under your nail known as a subungual hematoma. In addition to a noticeable color change, you may also feel pain or tenderness. As long as this discoloration moves along the growth of your nail, it’s a reassuring sign that it’s just a subungual hematoma.

You may also notice that your injured nail becomes thicker and overgrown over time, due to repetitive trauma — especially if it’s your big toe, or your longer second toe. This is known as onychogryphosis or ram’s horn nails. A nail injury can also lead to an ingrown toenail or white spots on your nails.

Moles or melanoma

A concern about nail color is one of the most common complaints dermatologists hear, Dr. Poblete-Lopez says. Discolorations usually appear in lines that run from cuticle to tip, and they can be benign moles or subungual melanomas.

You should consult a dermatologist if the skin under the nail plate — the hard part of the nail, covering the fingertips — develops any brown coloring, she says. These developments are always more of a concern if they affect a single finger instead of all. Brown lines that run into the cuticle could be a sign of melanoma. Ones that stop at or before the cuticle are likely caused by moles or a proliferation of pigment cells (called melanocytes) in our nail matrix due to a variety of things such as new medications.

African American and Asian populations are more likely to experience normal pigmentation changes that are related to ethnicity. These usually affect more than one nail.

Psoriasis

Psoriasis is a common skin condition that’s usually characterized by scaly, red patches on the skin, but it can also impact fingernails and toenails, Dr. Poblete-Lopez says. If you have yellow-red discoloring on your nail, often called an “oil drop” or “salmon patch,” you should consult your dermatologist.

Other symptoms that can also indicate nail psoriasis include:

• Indentations: You may notice nicks or pits on the nail plate.
• Beau’s lines: These lines run side-to-side across the nail.
• Skin thickening/nail loosening: Thickening of skin under the nail can dislodge the nail (onycholysis) from the nail bed. This generally starts at the tip and works their way toward the cuticle.
• White areas: Distinct white spots on the nails are called leukonychia. (The cloudy white spots that sometimes appear on fingernails and toenails don’t fall into the category and aren’t cause for concern.)
• Black lines: Black lines running from tip to cuticle could be tiny clots called splinter hemorrhages or dilated and burst capillaries.
• Redness: If the usually pale areas near the cuticle turn red, it could be caused by congested capillaries.

Kidney disease

Several nail changes may indicate the presence of acute or chronic kidney disease including:

• Beau’s lines: These side-to-side lines can be a symptom of acute kidney disease.
• Ridged nails: You may have koilonychia (rough nails with ridges). These nails are also frequently spoon-shaped and concave, and they can point to iron-deficiency anemia.
• White streaks/spots: Similar to psoriasis cases, distinct white streaks and spots on nails can point to chronic kidney disease.

Arthritis

Small cysts that grow near or on the cuticles may arise with arthritis. These are benign (not cancerous) and best addressed by a hand surgeon.

Stress

Fingernails and toenails are closely related to hair, Dr. Poblete-Lopez says. Just as your hair might fall out after an illness or a prolonged period of stress, your nails can also exhibit these symptoms. Most frequently, stress will cause horizontal lines to appear on your nails.

Medication

Certain medications may cause nail changes. For example, some chemotherapy drugs may darken your nails or cause white bands across the nail. Certain antibiotics may cause a yellowish discoloration.

Vitamin deficiencies

If you have an iron, zinc or selenium deficiency, your nails may appear brittle, soft, thin and start to split. For example, koilonychia (or spoon nails) are often a sign of an iron-deficiency anemia. And black toenails can signal a vitamin B12 deficiency or anemia.

Yellow nail syndrome

This rare condition, which may be linked to circulation issues, results in yellow (or green), curved nails. Your nails also may become thick and fall off. Yellow nail syndrome typically happens in people over the age of 50. Other symptoms may include swelling (lymphedema) and fluid buildup in your lung tissue (pleural effusions).

Darier disease

Darier disease is a rare genetic disorder that causes a skin rash and appears mostly in adolescence. You may notice reddish nails that appear as red stripes or even broad, white strips that run from cuticle to tip. A V-shaped nick near the fingertip can also indicate this condition, Dr. Poblete-Lopez says.

Bottom line?

Preventing underlying conditions that impact your nails isn’t always possible, Dr. Poblete-Lopez says.

You can care for your nails by:

• Staying hydrated
• Eating a well-balanced diet
• Consuming enough vitamin B and zinc (these nutrients greatly strengthen your nails)

In many cases, changes to your nails can be normal and don’t always point to any undiagnosed health changes. But, if you have a question, consulting your doctor is always best.

“Anything that doesn’t look normal ought to be addressed,” says Dr. Poblete-Lopez. “Your best course of action is to see a doctor as soon as possible.”