Understanding and Managing Black Toenails: A Comprehensive Guide (2023)


After a rigorous walk or run, you might encounter the unsettling sight of a toenail turning black, blue, or gray, accompanied by swelling underneath. This phenomenon, known as a black toenail or subungual hematoma, often results from various factors, including repetitive impact during physical activities or accidental trauma.

Causes of Black Toenails

As you engage in walking or running, the constant forward movement within your shoes can lead to your toes colliding with the shoe's top, front, and sides. Combined with the swelling of your feet during these activities, the pressure exerted by socks and shoes can cause soreness, damage to toenail beds, and the formation of a blister beneath the toenail. Opting for running shoes designed for wide feet may mitigate this pressure and reduce the risk of black toenails.

Treatment Options

In the initial stages, if a blister forms beneath the toenail, it's advisable to observe for 24 hours before considering intervention. If the toenail remains raised and painful after this period, seeking medical attention is recommended. Draining the excess blood, also known as trephination, can be performed by a professional or, in some cases, at home. However, individuals with diabetes should always consult a healthcare professional to avoid potential complications.

Draining the Black Toenail

For raised and painful black toenails, draining is a viable option to relieve pressure. This procedure involves creating a hole in the nail to release accumulated blood. While it's preferable for a professional to perform this, some individuals choose to do it at home. Diabetic individuals should refrain from attempting this at home due to the risk of infection. Persistent swelling and redness post-draining necessitate a doctor's evaluation for potential infection.

When to Seek Medical Attention

Should your swollen toe persist or become painful, producing discharge or exhibiting an odor, prompt consultation with a healthcare provider is crucial. Timely medical attention can prevent complications such as infections that may lead to severe consequences, particularly for individuals with diabetes.

Losing a Toenail

In cases where a black toenail is raised, it is likely that the toenail may be lost. Over the course of a few weeks or months, as the new toenail grows, it gradually displaces the damaged one. While awaiting full replacement, individuals may opt to paint the affected toenail to mask any visual differences. The complete replacement process typically takes around three months, resulting in a toenail that may initially appear slightly uneven but eventually returns to normal after four to five months.

Preventing Black Toenails

Properly fitting running or walking shoes and socks are essential in preventing black toenails. Given that feet can swell up to a full shoe size during extended physical activities, ensuring adequate space for toe expansion is crucial. Correct lacing techniques further eliminate the trauma caused by toes repeatedly hitting the shoe, especially during uphill and downhill segments of your exercise routine.

Other Causes of Black Toenails

Beyond physical trauma, fungal infections and rare cases of malignant subungual melanoma can also lead to black toenails. Over-the-counter antifungal treatments may be effective, but if symptoms persist, consulting a healthcare professional is advised. Malignant subungual melanoma typically presents as a black line extending from the cuticle, and immediate medical attention is essential if this is suspected.


In conclusion, while black toenails can be a consequence of physical activity, understanding the causes, treatment options, and preventive measures is paramount. By prioritizing proper footwear, attentive foot care, and timely medical intervention when needed, individuals can maintain both their foot health and the aesthetics of their toenails.


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Author: Van Hayes

Last Updated: 11/10/2023

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