A black toenail can be a harmless result of everyday activities or indicate a more serious underlying condition. Understanding the various reasons a toenail might turn black is important for determining when to seek medical advice. The discoloration beneath the nail signals changes that warrant attention.
Common Reasons for Black Toenails
One of the most frequent causes of a black toenail is trauma, leading to what is medically known as a subungual hematoma. This occurs when an impact, such as stubbing a toe or dropping an object on the foot, or even repetitive pressure from ill-fitting shoes, causes small blood vessels under the nail to rupture. The blood then pools in the confined space between the nail and the nail bed, resulting in a dark blue, purple, or black appearance. This bleeding beneath the nail creates pressure, which can cause pain and tenderness.
Certain fungal infections, specifically onychomycosis, can also cause toenail discoloration that appears dark brown or black. Fungi thrive in warm, moist environments, and as they infect the nail, they can lead to a buildup of debris underneath, which causes the dark hue. Beyond discoloration, fungal infections might also present with nail thickening, crumbling, or an unpleasant odor.
In rare instances, a black streak or spot under the nail could be a sign of subungual melanoma, a serious form of skin cancer. This type of melanoma often appears as a dark vertical band that may widen or change in appearance over time, and it is not typically caused by an injury. Though uncommon, awareness of this possibility is important.
When to Consult a Doctor
Consult a medical professional if a black toenail appears without a known injury, as this could suggest a more serious underlying cause. Persistent pain, swelling, redness, pus around the nail, a foul odor, or discoloration spreading beyond the nail plate to the surrounding skin indicate a need for medical attention.
Medical evaluation is also recommended if the discoloration does not grow out with the nail or if its size or color changes over time. If a fungal infection is suspected and does not respond to home care, or if you have conditions like diabetes that complicate foot health, professional assessment is important. Any dark streak appearing without injury, widening, or changing in appearance warrants immediate consultation due to the rare but serious nature of subungual melanoma.
Treatment Approaches and Healing
Treatment for a black toenail varies significantly depending on its underlying cause. For a subungual hematoma, small, non-painful cases may simply resolve as the nail grows out over several months. However, for large or painful hematomas, a medical professional might perform a procedure called trephination to drain the trapped blood and relieve pressure. This involves creating a small hole in the nail plate using a sterile instrument, which can provide immediate pain relief.
In cases of fungal infection, a doctor may prescribe antifungal medications, which can be topical solutions applied directly to the nail or oral medications. These treatments often require consistent use over several months to be effective, as the new, healthy nail must grow out to replace the infected portion. For subungual melanoma, surgical removal of the affected area, and often the entire nail, is typically necessary, sometimes followed by further medical evaluation or treatments like immunotherapy for more advanced cases.
During the healing process, proper nail care is beneficial regardless of the cause. Keeping the area clean and dry helps prevent complications like secondary infections. Toenail growth is a slow process, and complete resolution of discoloration can take several months as the nail naturally replaces itself.
Preventing Future Discoloration
Preventing future black toenails involves adjustments to foot care and footwear. Wearing properly fitting shoes is important, especially during physical activities like running or hiking, to prevent repetitive trauma and pressure on the toes. Shoes that are too tight can cause the toes to repeatedly hit the front or top of the shoe, leading to injury.
Maintaining appropriate toenail length is another important preventive measure. Trimming toenails straight across, rather than rounding the corners, helps prevent ingrown nails and reduces the risk of the nail impacting the shoe. It is also advisable to avoid cutting nails too short, as this can increase susceptibility to injury.
Good foot hygiene, including keeping feet clean and dry, can significantly reduce the risk of fungal infections. This involves drying feet thoroughly after washing and wearing clean socks daily. In environments where feet might be exposed to impact, such as certain sports or work settings, wearing protective footwear can also safeguard against traumatic injuries to the toenails.