Having one fingernail that is a different color than the others can mean a few different things. Here are some quick answers to questions about what it might signify:
Can it be caused by an injury or infection?
Yes, an injury or infection in the nail bed can sometimes cause one nail to become discolored or change texture while the others remain normal. This could be due to trauma, fungal infection, or even melanoma (skin cancer) in rare cases.
Is it a sign of a vitamin deficiency?
Potentially. Certain vitamin deficiencies, like low levels of B vitamins, zinc, or iron can occasionally manifest as nail discoloration or lesions on one or more nails.
Can it indicate a more serious underlying health condition?
Sometimes a discolored nail can signal an internal issue like liver disease, diabetes, anemia, or even heart, kidney or lung conditions in isolated cases. However, one discolored nail alone is rarely a sign of serious disease.
Is it caused by nail polish or artificial nails?
Using darker colored nail polish or acrylic/gel polish on one fingernail could easily explain why it looks different than bare natural nails on the other fingers. This is a very common reason.
Can certain medications be the cause?
Yes. Some medications like certain antibiotics, blood pressure medications, arthritis drugs, and chemotherapy agents can sometimes cause single nail discoloration as a side effect.
When should you see a doctor about one discolored nail?
See your doctor promptly if the nail is also misshapen, brittle, splitting, or has changes in texture. Also see your doctor if the color change does not go away on its own within a few weeks, or if other worrisome symptoms accompany it.
What are the most common causes?
Here is a table summarizing the most frequent reasons one fingernail may change color or appearance:
| Cause | Description |
|---|---|
| Nail polish | Colorful nail polish applied to one nail |
| Injury | Trauma affecting the nail bed |
| Fungal infection | Fungus infecting one nail |
| Medications | Side effect of certain medicines |
| Vitamin deficiency | Lack of vitamins like B12 or zinc |
| Aging | Normal change as we age |
| Melanoma | Rare pigmented cancer of one nail |
As you can see, there are a wide variety of potential reasons for a single discolored fingernail, ranging from benign to serious. In most cases it is nothing to worry about, especially if the color change seems to correspond to use of nail polish or trauma to the nail.
What does a black fingernail generally mean?
A black fingernail is most often caused by one of the following:
– Bruising under the nail (subungual hematoma): Collection of blood under the nail due to injury. This can make the nail appear black or purple. It will usually grow out with the nail over several months.
– Fungal infection: A fungal infection can make a nail thick, brittle and dark. The dark coloring may be black.
– Bacterial infection: In rare cases, a bacterial infection of the nail bed may cause a blackening of the nail. This requires medical treatment.
– Melanoma: The pigmented cells of melanoma can discolor a nail black. However, this is a very rare cause.
– Nail polish: Black nail polish can also turn a nail black, obviously. This will resolve if you remove the polish.
What about a white fingernail instead of black?
Some potential causes of a white fingernail include:
– Minor injury that damages the base of the nail plate. This can leave a white discoloration that grows out with the nail.
– Allergic reaction affecting one nail. This could cause whitening of the nail bed.
– Fungus infection, which can make the nail appear white, opaque or chalky.
– Psoriasis: This condition can cause pitting and discoloration of the nail, including white spots or streaks.
– Vitamin or mineral deficiency: Lack of zinc or other nutrients may manifest as white spots on nails.
– Liver or kidney disease: In some cases, chronic disease affecting these organs can cause pale nail discoloration.
– Aging: Nails can develop white tips or streaks due to aging processes.
– Nail products: Using certain cosmetic products like nail polish remover excessively can whiten a nail.
What about a yellow fingernail instead of black/white?
Some potential reasons for a yellow discolored fingernail include:
– Thickening of the nail: As nails naturally thicken with age, they can take on a yellowish hue.
– Fungal infection: Fungal infections characterize by nail plate thickening and debris under the nail may appear yellow.
– Nail polish: Yellowed discoloration may happen under acrylic or gel polish, especially when it starts growing out.
– Onycholysis: This condition where the nail separates from the nail bed can lead to yellowing.
– Respiratory conditions: In rare cases, lung problems like chronic bronchitis can manifest as pale yellowish nails.
– Diabetes: Yellow nails may occasionally be a sign of uncontrolled diabetes.
– Lymphedema: Swelling and thickening of tissues from lymphedema can sometimes discolor nails yellow.
– Carotenemia: High levels of beta-carotene (from food) can collect in nails and turn them yellow-orange. This is harmless.
– Arthritis: Nail changes like yellowing can uncommonly occur with joint diseases like psoriatic arthritis.
What about a green fingernail instead of black/white/yellow?
Some potential causes of a green fingernail include:
– Pseudomonal bacterial infection: A greenish discoloration of the nail can be a sign of infection with Pseudomonas bacteria. This requires urgent medical treatment.
– Fungal infection: Certain fungal organisms may impart a greenish-yellow tint to an infected nail in some cases.
– Nail products: Using nail polish, acrylics or gel polish in green hues can obviously turn the nail itself green. This will grow out if polish is removed.
– Chemical exposure: In rare occurrences, repeated exposure to certain industrial chemicals has been linked to greenish discolored nails.
– Green nail syndrome: This condition of unknown cause results in green bands on nails, and primarily affects people with careers involving lots of hand washing like healthcare workers.
– Skin conditions: In unusual cases, skin disorders like psoriasis has been associated with greenish hue to affected nails.
– Blood disorders: Very rarely, green nails may be linked to internal issues like anemia or liver disease. These would normally affect all nails.
What about a brown fingernail instead of black/white/yellow/green?
Some potential reasons for brownish discoloration of a fingernail include:
– Fungal infection: One of the most common causes of a brown or dark nail is a fungal infection.
– Bacterial infection: In some cases, a bacterial infection of the nail can cause brown streaks or spots.
– Melanoma: The pigmented brown cells of melanoma under the nail can lead to brown streaks or patches.
– Chemical exposure: Repeated exposure to chemicals like formaldehyde has occasionally been linked to tan or brown nails.
– Nutritional deficiency: Lack of certain vitamins and nutrients may manifest as brownish discoloration or spots on nails.
– Medications: Some medications like antimalarials, antibiotics, heart medications and chemotherapy drugs can cause nail brown discoloration as a side effect.
– Smoking: Tobacco use may in some cases stain nails a yellowish-brown hue.
– Aging: Nails can develop dark spots and streaks due to aging processes.
– Diabetes: In some diabetics, elevated blood glucose has been associated with brownish discolored nails
What about a purple fingernail instead of black/white/yellow/green/brown?
Some potential causes of a purple fingernail include:
– Bruising under nail: If blood collects under the nail due to trauma, it may appear dark purple or black until the discoloration grows out.
– Reddish-purple discoloration under the nails can potentially indicate heart disease, lung disease, or oxygen deprivation. These require prompt medical assessment.
– Purple streaks may rarely reflect a melanoma or other skin cancer affecting the nail matrix.
– Inflammation around the nail can sometimes manifest as a purple tinge to the nail. This could be due to injury, infection or autoimmune disease.
– Nail fungus can potentially cause a dark purple or brown discoloration.
– Certain antibiotics like tetracycline have been known to stain nails a bluish-purple hue.
– Using nail polish in purple or dark hues can temporarily stain the nails purple until it grows out or is removed.
Conclusion
In summary, a wide range of causes can result in a single fingernail becoming a different color than the other nails. Some common reasons include nail polish, injury, infection, medication side effects, and vitamin deficiency. Most of the time it is benign, but certain color changes like black, purple or green may need medical assessment. Look for changes in nail texture and abnormalities in shape as well as monitoring for other symptoms to determine if a doctor visit is advised. With treatment of the underlying cause where necessary, in most cases the discoloration will grow out with the nail over time.