A black toenail or a black toe can be alarming, but the cause is often harmless. The color usually comes from blood under the nail or skin, not from dead tissue. However, a black toe can sometimes signal a serious medical problem like an infection or poor blood flow. You should worry if the black area is spreading, painful, warm, or if you have diabetes or circulation problems—this requires prompt medical attention.
What Causes A Toe To Turn Black?
The most common reason a toe turns black is a subungual hematoma. This is simply a collection of blood under the nail. It usually happens after stubbing your toe, dropping something on it, or wearing shoes that are too tight—especially during long runs or hikes.
The blood pools under the nail and oxidizes, turning from red to dark purple or black. This is essentially a bruise. It looks alarming but is not dangerous on its own. The nail may eventually fall off and grow back, which can take several months.
Another common cause is a fungal infection. Some types of fungus can cause the nail to thicken and discolor, sometimes appearing black or dark brown. This is more common in older adults and people who spend a lot of time in damp environments like swimming pools or communal showers.
Less common but more serious causes include melanoma—a type of skin cancer—and peripheral artery disease, where narrowed blood vessels reduce blood flow to the feet. Both require urgent medical evaluation.
How To Tell If It Is Just A Bruise
If the black color appeared right after an injury, it is almost certainly a bruise. The key question is whether the color is fading or changing. A bruise will slowly resolve over days or weeks. The black area may move down the nail as it grows out, which is a good sign.
Pain is also a clue. A fresh bruise is often tender to the touch. This tenderness usually fades within a few days. If the pain is severe or getting worse, that points to something other than a simple bruise.
Press on the black area. If it blanches—turns lighter when pressed and then returns to dark—this suggests blood flow is still present. If the area stays completely dark and does not change at all, that may indicate reduced circulation or dead tissue.
Keep in mind that a bruise does not spread beyond the original injury site. If the black area is growing larger over time, that is a warning sign.
When A Black Toe Signals Poor Circulation
Peripheral artery disease (PAD) can cause a toe to turn black. This happens when plaque builds up in the arteries, restricting blood flow to the lower limbs. Without adequate blood supply, tissue can die—a condition called gangrene.
People with diabetes, high cholesterol, high blood pressure, or a history of smoking are at higher risk for PAD. If you have any of these risk factors and notice a black toe without a clear injury, seek medical care quickly.
Other signs of poor circulation include cold feet, leg cramps when walking, shiny skin on the legs, and weak pulses in the feet. If the black toe is accompanied by any of these symptoms, do not wait to see if it improves. This is a medical emergency.
Gangrene is serious. It can spread quickly and may require surgical removal of dead tissue. Early treatment can save the toe—or even the foot.
Could It Be Skin Cancer?
Melanoma can develop under a toenail. This is called subungual melanoma, and it is rare but dangerous. It often appears as a dark streak or band under the nail, rather than a solid black area.
The key difference from a bruise is that melanoma does not heal or fade over time. It may also extend beyond the nail into the surrounding skin. This is known as Hutchinson’s sign—dark pigment on the skin at the base or sides of the nail.
Melanoma under the nail is more common in people with darker skin and typically affects the big toe or thumb. If you have a dark spot under your nail that is not from an injury and does not go away, see a dermatologist. A biopsy is the only way to confirm whether it is cancer.
Do not assume a dark nail is cancer—most are not. But do not ignore a persistent dark spot either. Early detection of melanoma makes a significant difference in treatment outcomes.
Black Toe In People With Diabetes
Diabetes changes the rules. If you have diabetes and your toe turns black, treat it as an emergency. Do not wait to see your regular doctor. Go to urgent care or the emergency room.
Diabetes can cause two problems at once: reduced blood flow and nerve damage. Reduced blood flow means the toe may not heal well. Nerve damage means you may not feel pain even when there is a serious problem. These two factors together can turn a minor issue into a severe one quickly.
Black tissue in a diabetic foot is often a sign of tissue death. It can become infected easily, and infections in diabetic feet can spread to the bone. This is how many diabetes-related amputations begin.
Keep your feet clean and dry. Check them daily for any color changes, cuts, or blisters. If you notice a black area, do not try to treat it at home. Professional evaluation is essential.
What To Do At Home
If you are certain the black toe is from a recent injury and you have no circulation problems, home care is usually sufficient. Rest and elevate your foot. Apply ice wrapped in a cloth for 15 to 20 minutes at a time during the first 24 to 48 hours.
Over-the-counter pain relievers like acetaminophen or ibuprofen can help with discomfort. Follow the dosing instructions on the package. Do not exceed the recommended dose.
Wear shoes with a wide toe box to avoid pressure on the injured nail. If the nail is loose, leave it alone. Do not pull it off. It will separate naturally when it is ready.
If blood is trapped under the nail and causing throbbing pain, a clinician may drain it. This involves making a small hole in the nail to release the pressure. This should only be done by a professional—doing it yourself increases the risk of infection.
When To See A Doctor Immediately
Seek medical care right away if the black toe is accompanied by fever, redness spreading up the foot, warmth, or a foul odor. These are signs of infection. Infection can spread rapidly and become life-threatening.
See a doctor the same day if you have diabetes, peripheral artery disease, or a weakened immune system. These conditions make you more vulnerable to complications.
Also seek care if the black area is growing, if you have no idea what caused it, or if it has not changed after two to three weeks. Persistent discoloration needs a professional evaluation.
Do not wait for severe pain. By the time pain is severe, the problem is often advanced. When in doubt, err on the side of caution.
Why Is My Toe Black And When Should I Worry?
The short answer is that a black toe from a recent injury is usually a bruise and will heal on its own. Worry if you have diabetes or circulation problems, if the black area is spreading, if there are signs of infection, or if the discoloration appeared without any injury and persists for weeks.
Trust your instincts. You know your body better than anyone. If something feels wrong, it probably is. A quick medical evaluation is always better than waiting to see what happens.
Frequently Asked Questions
Can a black toenail heal on its own?
Yes, if it is a bruise from an injury, it will usually heal on its own over several weeks or months. The nail may fall off and regrow, which is normal.
Is a black toe an emergency?
It is an emergency if you have diabetes, poor circulation, or signs of infection like spreading redness, warmth, or fever. Otherwise, it is usually not urgent.
How long does a black toenail take to grow out?
A toenail takes about 6 to 12 months to fully regrow. The black area will move forward as the nail grows.
What does a black toe from poor circulation look like?
It often looks dark or purple-black and may be cold to the touch. It usually appears without an injury and may be accompanied by leg pain or cramping.
