A discolored toenail, particularly one that appears black, often signals an underlying change or issue within the nail unit. This common concern can stem from various reasons, ranging from minor trauma to more serious health conditions, making it important to understand the potential causes.
Understanding the Causes of Black Toenails
Trauma frequently causes black toenails, often due to a subungual hematoma. This occurs when blood vessels beneath the nail rupture from impact, tight-fitting shoes, or repetitive stress during activities like running or hiking. The pooled blood darkens as it oxidizes, creating the black appearance, and the discoloration gradually grows out with the nail over several months.
Fungal infections, or onychomycosis, can also lead to toenail discoloration. These infections typically cause the nail to thicken, become brittle, and develop a crumbly texture. The dark color can result from fungal debris accumulating under the nail or from the fungi producing pigments.
Certain bacterial infections, particularly those caused by Pseudomonas aeruginosa, can result in a distinctive greenish-black nail discoloration. This bacterium thrives in moist environments and can produce pigments like pyocyanin and pyoverdin, which stain the nail. The discoloration is often accompanied by a foul odor and can sometimes be seen as a localized spot under the nail.
Some medications can induce nail color changes as a side effect. For instance, certain chemotherapy drugs, antimalarial medications like chloroquine or hydroxychloroquine, and some antibiotics such as minocycline can cause diffuse or streaky dark or black discoloration. These changes usually resolve after the medication is discontinued.
Underlying systemic health conditions can also cause toenail discoloration. Diseases affecting circulation, such as peripheral artery disease or diabetes, can reduce blood flow to the extremities, leading to nail changes and discoloration over time. Kidney disease and cardiovascular issues may also contribute to nail abnormalities.
While rare, a persistent dark streak or patch under the toenail could indicate subungual melanoma. Unlike a bruise that grows out with the nail, a melanotic streak often remains or expands, sometimes involving the nail fold and cuticle. Any new, unexplained, or changing dark discoloration under the nail, especially one that does not resolve or appears as a linear band, warrants professional evaluation.
When to Seek Medical Attention for a Black Toenail
Consulting a healthcare professional is advisable if toenail discoloration appears without a clear history of trauma or if it persists and worsens over time. Pain, swelling, or pus around the nail are signs of a potential infection requiring medical assessment and specific treatment.
A dark streak that runs the entire length of the nail and extends into the cuticle, known as Hutchinson’s sign, is a concerning indicator that necessitates immediate medical attention. This particular sign can be a strong predictor of subungual melanoma. Early detection is important for better treatment outcomes.
Consult a doctor if nail changes are accompanied by other systemic symptoms, such as fever, fatigue, or unexplained weight loss. These symptoms may suggest an underlying health condition. If the cause of discoloration remains unknown or does not improve over several weeks, a professional diagnosis is beneficial. Individuals with underlying health conditions, such as diabetes or compromised immune systems, should also consult a doctor promptly for any toenail changes due to increased susceptibility to complications.
Preventing Toenail Discoloration
Wearing properly fitting footwear helps prevent traumatic black toenails. Shoes that are too tight or too loose can cause friction and impact, leading to bleeding under the nail. Ensuring adequate space for toes, particularly during physical activities, can significantly reduce the risk of injury.
Maintaining good foot hygiene is another important preventative measure against fungal and bacterial infections. Keeping feet clean and thoroughly dry, especially between the toes, discourages the growth of microorganisms. Regular washing and drying after bathing or exercise helps prevent microbial growth.
Trimming toenails straight across and not too short helps prevent ingrown nails. This technique reduces the risk of the nail edge digging into the skin, which can cause inflammation and lead to infections. Using clean, sharp nail clippers also supports overall nail health.
Using protective footwear during activities that might cause impact, such as sports or heavy labor, provides an additional layer of defense. Steel-toed boots or athletic shoes designed for specific sports can shield nails from trauma. Proper foot care can help maintain healthy toenails and reduce the likelihood of discoloration.