Have you noticed that one or more of your toenails have started to turn black? A black toenail can be alarming, but in most cases it’s harmless. In this comprehensive article, we’ll walk through all the potential causes so you can get to the root of the issue.<\/p>\n
If you’re short on time, here’s the quick answer: Black toenails are often caused by injury, fungal infections, or medical conditions<\/b>. The most common causes are trauma from tight shoes, dropping something on your toe, and toenail fungus.<\/p>\nWhat Causes Black Toenails?<\/h2>\n
Black toenails, known medically as subungual hematomas, can occur for various reasons. Understanding the potential causes can help determine appropriate treatment and prevent future occurrences.<\/p>\n
Physical trauma is the most common culprit behind black toenails. Activities like running, hiking, or playing sports can cause the toenail to jam into the toe bed, rupturing capillaries and vessels. Blood pools underneath the nail, staining it black or purple as it oxidizes.<\/p>\n
Ill-fitting shoes are a prime offender. Pressure from tight shoes causes repetitive injury over time. One study found nearly 50% of runners<\/b> develop black toenails from poorly sized running shoes.[1]<\/sup> Wider toe boxes reduce friction to prevent this.<\/p>\n A fungal infection (onychomycosis) can also blacken toenails. Fungi invade the nail bed and cuticle, causing thickening, distortion, debris build-up, and dark pigmentation.<\/p>\n Those with nail fungus may notice odor or a foul smell, nail detachment, or white spots on surrounding skin. Once established, toenail fungus is stubborn to treat. But oral and topical antifungal medications can help clear infection and restore normal nail color.<\/p>\n Certain underlying medical conditions are linked with black toenail discoloration:<\/p>\n Therefore, it’s wise to see a podiatrist or doctor if the cause of black toenails is uncertain. They can assess for related medical issues and provide proper treatment.<\/p>\n Wearing shoes that are too tight can cause repeated trauma to the toes over time. This constant squeezing and friction can damage the toenails and cut off circulation, leading them to turn black. Some studies have found up to 60% of runners experience black toenails due to tight shoes<\/b>.<\/p>\n The medical term for this is “subungual hematoma,” which refers to bleeding underneath the nail. Relieving the pressure by wearing properly fitted shoes allows fresh blood to circulate and the nail to heal.<\/p>\n Dropping a heavy object like a weight or piece of furniture directly on your toenail can instantly cause bleeding and bruising. The impacted toe might throb with pain and the nail can turn fully or partially black within a day or two.<\/p>\n If it’s just bruised and intact, the discoloration grows out with the nail over several months. But if the crush injures the nail bed or causes the nail to partly or fully come off, it will need to regrow the damaged part.<\/p>\n Stubbing your toes happens to everyone at some point! You might bang your toe into furniture, the stairs, a doorway, or someone’s foot during sports. While painful, most of these impacts only cause temporary bruising and some tenderness.<\/p>\n But a harder trauma that fractures the toe or severely damages the nail can lead to blackening under or over the entire nail. See a doctor if part of the nail is lifted, the toe won’t stop throbbing, or you can’t put weight on it.<\/p>\n Logging high weekly mileage training for marathons or ultramarathons increases the chances of developing black toenails. The constant pounding sensation absorbs impact to the feet with each step. Over time, this can cause blood vessels under the nails to rupture.<\/p>\n A 1982 study<\/a> showed 79% of marathon participants had subungual hematomas afterwards. Wider toe box shoes, properly trimming nails, and wearing thin moisture-wicking socks can alleviate some pressure.<\/p>\n Certain groups have an elevated risk of developing fungal toenail infections. Older adults are more likely to get fungal nails since immunity weakens with age. According to the CDC, adults aged 65 years or older made up over 50% of fungal nail infections.<\/p>\n Having diabetes is another major risk factor – about 36% of people with diabetes develop onychomycosis. The high blood sugar levels make it harder to fight infections. Other medical conditions like psoriasis or athlete’s foot also raise the risk.<\/p>\n Lifestyle factors like swimming frequently, wearing tight shoes, walking barefoot in damp places, or injuring the toenail make fungal overgrowth more likely. Genetics and family history play a role too.<\/p>\n The most common early signs are a white or yellow spot under the tip of the toenail. As the infection progresses, the nail thickens and discolors, turning white, black, brown, or green with debris buildup. The nail may become brittle and crumbly.<\/p>\n In severe cases, the nail separates from the bed and falls off. There can be an unpleasant odor too. Mild infections may not cause pain, but the nail area can become red, swollen and painful if left untreated. See a podiatrist promptly if any symptoms occur to prevent worsening.<\/p>\n Doctors often diagnose fungal nail infections through visual exam of the toenails. They may also take a nail clipping or debris sample for lab tests to identify the exact fungus. According to the American Academy of Dermatology<\/a>, microscopic exam and fungal culture of nail specimens can determine the causative fungus in over 90% of onychomycosis cases.<\/p>\n PCR (polymerase chain reaction) tests offer quick and accurate diagnosis. Imaging like X-rays helps gauge infection depth in the nail bed. Proper diagnosis is key before starting treatment.<\/p>\nFungal Infection<\/h3>\n
Medical Conditions<\/h3>\n
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Trauma and Injury<\/h2>\n
Tight Shoes<\/h3>\n
Dropping Something on Your Toe<\/h3>\n
Hitting Your Toe<\/h3>\n
Long Distance Running<\/h3>\n
Fungal Infection<\/h2>\n
Risk Factors<\/h3>\n
Symptoms<\/h3>\n
Diagnosis<\/h3>\n
Treatment<\/h3>\n