A black toenail is a dark discoloration under the nail plate, ranging from blue or purple to deep brown or black. While often alarming, many instances are not serious and result from common occurrences.
Understanding the Causes of Black Toenails
A subungual hematoma, or bruise under the nail, is a frequent cause. This occurs when small blood vessels rupture, leading to blood pooling. Common causes include direct trauma, such as stubbing a toe or dropping an object on the foot.
Repetitive micro-trauma from ill-fitting shoes or activities like running can also cause a subungual hematoma. Shoes that are too tight or loose allow toes to repeatedly hit the front, damaging the nail bed. This accumulated impact results in bleeding and discoloration.
Fungal infections (onychomycosis) are another common cause of toenail discoloration. Fungi can invade the nail, changing its color to dark brown or black. These infections can also cause the nail to thicken, become brittle, and separate from the nail bed.
Discoloration from a fungal infection often results from fungal debris or pigments. Fungi thrive in warm, moist environments, making toenails susceptible, especially for those who frequently wear closed-toe shoes or spend time in communal damp areas like locker rooms.
In rare cases, a black toenail can signal subungual melanoma, a type of skin cancer under the nail. Unlike a bruise, this dark discoloration typically appears as a streak that may widen over time and can extend to the skin around the cuticle (Hutchinson’s sign).
Melanoma under the nail usually progresses slowly, with a subtle early appearance. Other less common causes include certain medications, like some chemotherapy drugs, which can cause pigment changes. Systemic diseases affecting blood clotting or circulation can also lead to nail discoloration.
When a Black Toenail Needs Professional Attention
While many black toenails resolve on their own, medical evaluation is beneficial for certain signs. Severe pain or a throbbing sensation under the nail can signify pressure from a subungual hematoma. A healthcare provider may need to drain the blood to relieve this discomfort.
Signs of infection around the toenail also warrant professional attention. These include increasing redness, swelling, warmth, or pus around the nail or surrounding skin. An infection can develop if the skin barrier is compromised, allowing bacteria to enter the nail bed.
If the dark discoloration under the nail spreads, changes rapidly, or appears without a clear traumatic event, seeking medical advice is prudent. This is particularly relevant when the cause is unknown or it appears spontaneously without injury.
Any concern about melanoma under the nail should prompt an immediate visit to a healthcare professional. Indicators include a dark streak extending from under the nail to the cuticle or surrounding skin, irregular borders, or changes in size or shape. Unlike a bruise, which grows out with the nail, a melanotic streak will persist.
If the black toenail persists for an extended period without showing signs of improvement or growing out with the nail, it is advisable to have it evaluated. This is especially true if the nail remains discolored for several months or if new symptoms develop. A medical professional can diagnose the cause and recommend treatment.
Managing and Preventing Black Toenails
For minor cases of black toenails resulting from trauma, basic home care can often be sufficient. If a mild subungual hematoma forms, applying cold compresses and elevating the foot can help reduce swelling and discomfort. Protecting the toe from further injury is also important as the nail grows out.
Proper footwear plays a significant role in preventing black toenails, especially for individuals engaging in physical activities. Wearing shoes that fit well, with adequate space in the toe box, can prevent repetitive trauma to the toenails. For athletes, selecting appropriate athletic shoes designed for their specific activity can minimize impact.
Maintaining good nail hygiene is also a practical step in prevention. Regularly trimming toenails straight across and not too short helps prevent ingrown nails and reduces the likelihood of trauma. Keeping feet clean and dry, especially after showering or exercising, helps prevent the growth of fungi that can lead to discoloration.
Allowing feet to air out and wearing breathable socks made of moisture-wicking materials can further reduce the risk of fungal infections. It is also advisable to wear protective footwear in communal areas like public showers or swimming pools. Regularly monitoring the appearance of your toenails can help you identify any changes early.