Medically Reviewed by
Dr. Peter Hanna, DPM
Board Certified Podiatrist
You glance down after a long run or a rough day at work and notice it. One toenail has turned dark purple or black. Maybe it hurts, maybe it doesn’t. Either way, it’s the kind of thing that sends people straight to a search bar.
Most of the time, a black toenail is a bruise from injury or pressure. But other causes exist, and a few deserve a closer look. In this guide, we explain what a black toenail usually means, how to care for it, how fungus and nail melanoma can look similar, and when to see a podiatrist.
The most common explanation is a bruise under the nail. Doctors call it a subungual hematoma. Blood pools between the nail plate and the nail bed, and because the blood has nowhere to go, the nail looks black, purple or black-and-blue.
Cleveland Clinic describes a subungual hematoma as a bruised nail that develops after trauma to the nail, such as dropping something heavy on your toe. It also notes that these injuries are typically minor, and the pain usually gets better within a few days. If that fits your story, there’s good reason to feel reassured.
A bruised toenail can be surprisingly uncomfortable. Cleveland Clinic lists severe or throbbing pain, nail discoloration, a nail that is very tender to the touch, and sometimes separation of the nail plate from the nail bed. The color may look black-and-blue or black-and-purple.
Many people searching for a black spot on toenail see a smudge or patch, not a line. That’s a useful clue. The same source says hematomas look more like a dark bruise or smudge under the nail, and they typically show up quickly, often within hours of an injury.
You don’t need a dramatic injury. Cleveland Clinic explains that a bruised nail can also come from repetitive pressure over time, such as running in shoes that are too tight and press on a toenail. Runners and hikers often notice it after a long downhill stretch, when toes slide forward in the shoe.
That’s why shoe fit matters so much. If a black toenail appears and you can’t remember hitting your toe, think back over your recent footwear and activity. Tight toe boxes, new shoes and long training weeks are common culprits. Our guide on running shoes vs walking shoes explains how fit and design differ.
Patience is the hard part. Cleveland Clinic explains that the bruise grows out with the nail over weeks or months. The color may start red or purple, then turn dark brown or black as the injury heals.
It may take six to nine months for the nail to grow out completely and return to its normal color, according to the same source. Even after treatment, the nail can look discolored for many weeks. That doesn’t mean something went wrong. As the nail grows, you should see the dark patch move away from the cuticle.
If you have a bruised nail with no other apparent damage, Cleveland Clinic says you can generally care for it at home with ice. Wrap the ice in a soft cloth before putting it on your skin, so it doesn’t touch directly.
Wear roomy, comfortable shoes while it heals, and keep pressure off the toe when you can. Keep the area clean and dry. The same source advises seeking medical care if the pain gets worse over the next few hours. A bruise that is steadily getting more painful is telling you something, and it’s worth listening.
When a toenail feels tight and throbbing, it’s tempting to relieve the pressure with a needle or pin. Cleveland Clinic is clear on this point: you should never attempt to drain a subungual hematoma at home, and you should seek medical care instead.
A provider can perform a simple procedure called trephination, which drains the blood to relieve pressure. Doing it at home risks infection and doesn’t give anyone a chance to check for deeper injury. If the pressure is severe, call us or another medical provider rather than improvising.
Most bruised toenails heal on their own, but some injuries come with extra damage. Cleveland Clinic says to seek medical care right away if you have intense pain or pain that worsens over time, a deep cut or bleeding that won’t stop, or a feeling that a bone may be broken.
Infection is another concern, though it’s uncommon. Signs include red or discolored skin around the nail, swelling, pus-like drainage and fever. Our post on the warning signs of an infected ingrown toenail describes what infection around a toenail can look like.
Not every dark or discolored nail comes from injury. According to the American Academy of Dermatology, the first sign of nail fungus is usually a change to the nail, such as a different color on part of the nail. Other signs include a brittle nail that cracks or splits, and buildup under a discolored nail.
Fungus and bruises behave differently over time. The American Academy of Dermatology says nail fungus almost never goes away on its own and it can spread. A bruise that follows an injury, by contrast, slowly grows out. You can’t always tell by looking, so a nail that stays discolored, thickens or crumbles deserves an exam.
If fungus is the cause, scraping or filing won’t solve it. The American Academy of Dermatology notes that fungi live in the nail and in the tissue beneath it, so removing buildup only takes away some of the fungi. Prescription medication is needed to clear a fungal nail infection.
It also takes time. The same source says that even when treatment works, you’ll still see nail changes until the nail grows out, which can take a year or longer on the big toe. Our nail fungus treatment page covers our options, and our guide on how to get rid of toenail fungus explains what tends to work.
Here’s the part we don’t want to skip, and we want to say it calmly. Skin cancer can, rarely, develop under a nail. Cleveland Clinic reports that subungual melanoma accounts for about 0.7% to 3.5% of all melanomas worldwide. The overwhelming majority of black toenails are not cancer.
Still, the American Academy of Dermatology points out that nail melanoma is often diagnosed at a more advanced stage than melanoma on the skin, partly because people assume a dark nail is just a bruise. Knowing the warning signs helps you catch the rare problem early. This article can’t diagnose anything, and only an exam can tell what’s under your nail.
Cleveland Clinic says subungual melanoma usually appears as a dark vertical streak on the nail, running from the base toward the tip, like a line drawn with a marker. It may start small and widen over time. The discoloration can be irregular, with different shades of brown and black.
The American Academy of Dermatology and Cleveland Clinic both list other changes worth mentioning to a doctor: dark skin next to or around the nail, a nail that lifts away from the nail bed, a nail that splits, and a bump or nodule under the nail. Cleveland Clinic also lists bleeding or an ulcer. A change you can’t explain by injury is the key detail.
Think of three questions: what does it look like, when did it start, and what is it doing? A hematoma tends to look like a smudge or patch, appears within hours of an injury, and moves outward as the nail grows. Cleveland Clinic notes that blood may grow out or appear when you trim the nail.
Melanoma tends to look like a line, grows more slowly, and doesn’t clear as the nail grows. But the same source warns that nail cancer can sometimes resemble a hematoma. So if you’re unsure, or if the mark doesn’t match your history, don’t wait. Our melanoma screening page explains how we approach skin checks.
Anyone can develop it. But Cleveland Clinic says the risk is higher if you’re between 50 and 70 and have darker skin, and it’s more common in people of African American, Asian or Hispanic descent. A personal or family history of melanoma and being older than 50 are other risk factors listed.
Unlike most melanomas, subungual melanoma doesn’t appear to be caused by sun exposure, according to Cleveland Clinic. The American Academy of Dermatology adds that previous nail trauma may also be a risk factor. Because the cause isn’t fully understood, the best protection is simple awareness and checking your nails regularly.
If you have diabetes, a dark or changed toenail deserves extra attention. The CDC explains that about half of all people with diabetes have some kind of nerve damage, most often in the feet and legs, and it can lower your ability to feel pain, heat or cold.
That matters because pain is the body’s alarm. If you can’t feel a problem, a bruised nail, a blister or a small sore can go unnoticed and get worse. The CDC says small problems can become serious if they aren’t treated early, and people with diabetes can develop foot ulcers that get infected and heal poorly.
The CDC recommends checking your feet every day for cuts, redness, swelling, sores, blisters, corns, calluses, or any change to the skin or nails. Use a mirror if you can’t see the bottoms of your feet. Trim your toenails straight across, wear shoes that fit well, and never go barefoot.
The CDC lists thickened, yellow toenails, fungus infections and ingrown toenails among the symptoms that call for seeing a doctor right away, instead of waiting for the next appointment. Our diabetic foot care page and our post on early signs of diabetes in toenails go deeper.
Evaluation starts with your story and a close look. Cleveland Clinic says providers diagnose a hematoma by examining the toe, including the nail plate and nail folds, and may order an X-ray to check for a broken bone or other injury that isn’t visible on the surface.
If something looks suspicious, the next steps differ. For possible melanoma, Cleveland Clinic says a provider may use dermoscopy, which is a close look with a special microscope, or a biopsy, where a small tissue sample is tested. Looking with the naked eye has limits, which is exactly why a professional exam matters.
You can’t prevent every accident, but you can lower your odds. Cleveland Clinic suggests making sure your shoes fit well, so workout shoes don’t pinch or press on your toes, and wearing shoes or boots appropriate for the task when lifting heavy objects or doing manual work.
Avoid going barefoot or wearing open-toed shoes around anything heavy. Keep nails trimmed so they don’t catch or press in a snug shoe. If black toenails keep coming back despite good footwear, that pattern is worth discussing with a podiatrist, since foot structure can play a role.
Plan a visit if your toenail stays dark without a clear injury, if the dark area is a line instead of a smudge, if the nail lifts, splits or changes shape, or if pain keeps rising. Also see someone if the nail is thick or crumbly, or if you have diabetes. Our guide to what a podiatrist does explains what a visit involves.
Don’t wait for a suspicious change to resolve on its own. The American Academy of Dermatology advises making an appointment with a board-certified dermatologist for any new dark band on a nail, and we’re glad to help you decide who is the right person to see.
If a black toenail has you worried, a quick exam can give you a real answer. Our podiatry team evaluates nail and foot concerns for patients across Miami and takes the time to rule out the less common causes.
You can reach us by calling 833-735-3668 or through our contact page. This article is for general education and isn’t a diagnosis or a substitute for care from a qualified clinician. Nail discoloration has many causes, and only an in-person exam can tell you which one applies to you.
Most often, a bruise under the nail from an injury or repeated pressure, such as tight shoes during running. Fungus can also discolor a nail, and rarely, a dark nail can be a sign of a more serious condition. An exam is the only way to know for sure.
No. Nail melanoma is rare, accounting for roughly 0.7% to 3.5% of all melanomas. Most black toenails are bruises. A dark line with no clear injury, a growing streak, or dark skin around the nail should be checked, though.
The bruise grows out with the nail. Cleveland Clinic says it may take six to nine months for a nail to completely grow out and return to its normal color. Pain usually eases within a few days, but the color change lingers.
No. Cleveland Clinic advises against draining a subungual hematoma at home. A provider can do a simple drainage procedure safely and check for fractures or deeper injury. See someone promptly if the pain is intense or getting worse.
A bruise often shows up quickly after an injury as a smudge or patch and grows out. Fungus usually causes gradual color change, brittleness or buildup under the nail, and almost never goes away on its own. Both can look similar, so a professional exam helps.
It’s worth getting checked sooner. The CDC says nerve damage can reduce your ability to feel pain in your feet, so small problems can go unnoticed. People with diabetes should check their feet daily and call a doctor about nail changes instead of waiting.
See a doctor if you have intense or worsening pain, a deep cut, signs of infection, or a possible broken bone. Also schedule a visit if the nail is dark without an injury, has a dark streak, lifts, splits, or doesn’t improve as the nail grows out.
Cleveland Clinic. Subungual Hematoma
Cleveland Clinic. Subungual Melanoma (Nail Melanoma)
American Academy of Dermatology. How to check your nails for melanoma
American Academy of Dermatology. Nail fungus: FAQs
Centers for Disease Control and Prevention. Your Feet and Diabetes
Dr. Peter Hanna is a board-certified podiatrist and reconstructive foot & ankle surgeon with over 15 years of experience. He serves as Director of Podiatry at South Florida Multispecialty Medical Group, specializing in complex reconstruction, minimally invasive surgery, and diabetic foot care.
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