Toenails are naturally white in color. Sometimes discolorations can occur from nail polish, nutritional deficiencies, infection, or trauma. Black toenails are attributed to a variety of causes, some of which resolve on their own. If your nail doesn’t get better, you’ll need to see your doctor to rule out a more serious cause of black toenail.
A black toenail may be caused by:
- An underlying medical condition: This may include anemia, diabetes, heart disease, or kidney disease.
- Fungal infections: While these often look white or yellow, fungal infections can sometimes cause black toenails from debris buildup. Your toenails are especially vulnerable to fungal infections because they thrive on moist and warm environments.
- Melanoma: This is the most serious type of skin cancer, which often appears as a dark brown misshapen spot. Such spots can also occur underneath nail beds.
- Trauma: Usually caused by an injury, trauma to the toenail can cause the blood vessels beneath a nail to break. The resulting bleeding underneath the nail appears black.
A black toenail doesn’t necessarily require a doctor’s visit — the need for medical treatment depends on the initial cause. Knowing the cause can help you make this decision. On the flipside, if you don’t know the cause, it’s a good idea to see your doctor just in case your black toenail is a sign of a serious medical condition.
Not all cases of toenail fungus require a doctor’s visit. However, if you also have diabetes, you should see your doctor for treatment.
A dermatologist can also help diagnose and treat black toenail. You’ll need to see a dermatologist if you suspect melanoma. However, if your black toenail is caused by another underlying health issue, such as diabetes, then you’ll also need to see your primary doctor to treat the cause.
Any black toenail that doesn’t go away should be looked at by a doctor.
Toenail fungus that’s left untreated can spread throughout your feet and other parts of your body. It can also cause permanent nail damage.
Complications can also arise from melanoma in the toenail that’s mistaken for trauma-induced black toenail. It’s important to see your doctor if you notice any black spots that might be spreading throughout the nail, or if they don’t go away despite your toenail growing out.
Fungal infections of the toes are relatively treatable at home when caught early. Over-the-counter ointments, creams, and polishes are usually effective. Severe cases may require a prescription antifungal treatment.
If a black toenail is caused by an injury, the resulting spot from broken blood vessels will disappear once your nail grows out.
Black toenail caused by trauma from an injury usually resolves on its own without treatment. However, if your toenail grows out and it still appears black, then the symptoms might be related to another underlying cause.
Toenail discoloration related to diabetes and other health conditions requires treatment for the underlying causes.
How can someone who runs marathons distinguish a black toenail caused by trauma from a black toenail caused by something serious, such as melanoma?
Distinguishing a black toenail caused by trauma from that caused by melanoma sometimes is difficult. If there is any question, seek the advice of a dermatologist. A melanoma will often have a Hutchinson’s sign, which is characterized by a brown or black pigment in the nail bed that spreads to the cuticle and proximal or lateral nail folds. A black toenail from trauma doesn’t usually extend to the lateral nail folds and usually goes away without treatment as the nail grows. The takeaway is, if there is any question, seek the advice of a dermatologist.William Morrison, MDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
With black toenail, your outlook largely depends on the root cause of the symptom. Cases related to trauma and fungal infection have the best outlook. In these instances, injured nails grow out, and fungal infections may be treated at home.
Black toenail caused by melanoma and other health conditions are symptomatic. The outlook for such cases depends on how early you treat the underlying cause.
Keeping your nails clean and dry can help prevent some causes of black toenail. You can also take care to help prevent toenail trauma. This involves wearing closed-toe shoes when working so that your nails don’t get injured from dropped objects. Wearing proper-fitting shoes during exercise (especially running) can also help prevent toenail trauma.
When it comes to other underlying causes, you need to take other preventive measures. Reducing direct sun exposure to your feet and wearing sunscreen around your toes can help prevent melanoma. Black toenail attributed to other medical issues can be prevented through proper treatment and management of the underlying health condition.
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