A toenail that looks bruised is almost always a subungual hematoma, which is blood trapped between the nail plate and the nail bed after some kind of injury. The discoloration ranges from maroon to black and sometimes blue-white, and it can show up even when you don’t remember hurting the toe. But not every dark spot under a toenail is a simple bruise, and a few of the look-alikes deserve prompt attention.
Trauma Is the Most Common Cause
The overwhelming majority of bruised-looking toenails come from a direct blow or crush injury. Dropping something heavy on your foot, stubbing a toe against furniture, or having someone step on it during a sport can rupture tiny blood vessels in the nail bed. Blood pools beneath the nail plate, and because the nail itself is translucent, the trapped blood shows through as a dark discoloration. The color depends on how much blood collects and how old the injury is: fresh hematomas tend to look deep red or maroon, while older ones darken to purple or black as the blood breaks down.1Cureus. Traumatic Subungual Hematoma: A Case Report and Review of the Literature
The other classic scenario is repetitive microtrauma. Runners, hikers, and anyone who spends long hours on their feet in shoes that are even slightly too tight can develop “runner’s toe,” where the nail repeatedly bumps against the front or top of the shoe. Each individual impact is minor, but over miles and weeks the cumulative damage produces a hematoma that looks identical to one from a single acute injury. The big toenail and the second toenail are the usual victims because they extend furthest in most footwear. Many people with this kind of bruise never felt a single painful moment; they just notice the color one day after a shower.
A telltale sign that you’re dealing with a straightforward hematoma is throbbing pain right after the injury, caused by blood pressing against the sensitive nail bed. If the nail was hurt hard enough, you might also notice mild swelling around the cuticle area. Smaller hematomas may produce no pain at all, especially if the bleeding was slow or the blood had somewhere to spread.
Other Reasons a Toenail Can Look Bruised
Trauma accounts for most cases, but several other conditions can produce a dark, bruise-like appearance under the nail. Recognizing these possibilities matters because some require treatment you wouldn’t think to seek for a simple bruise.
Fungal and Bacterial Infections
Fungal nail infections, known clinically as onychomycosis, can make a toenail turn brown, dark yellow, or even black. The organisms responsible include common dermatophytes as well as yeasts and dark-pigmented molds. One documented combination involves the yeast Candida parapsilosis growing alongside Exophiala dermatitidis, a so-called black yeast, both of which thrive in warm, moist environments and can discolor the nail substantially.2PubMed Central. Case of Mixed Infection of Toenail Caused by Candida parapsilosis and Exophiala dermatitidis and In Vitro Effectiveness of Propolis Extract on Mixed Biofilm Fungal nails tend to be thick, crumbly, and sometimes smelly, which helps distinguish them from a bruise, but early infections can look deceptively similar to dried blood under the nail.
Bacterial infections from Pseudomonas aeruginosa produce green nail syndrome, where the nail turns greenish-yellow, greenish-brown, or greenish-black. This typically happens in people whose hands or feet are frequently wet. It can look alarming, but it’s treatable with antibiotics, particularly oral ciprofloxacin.3Europe PMC. Chloronychia: green nail syndrome caused by Pseudomonas aeruginosa in elderly persons If the discoloration has a greenish tint rather than a pure red-to-black spectrum, infection is more likely than a bruise.
Splinter Hemorrhages and Systemic Conditions
Sometimes the discoloration isn’t a single dark blot but thin, reddish-brown lines running lengthwise under the nail. These are splinter hemorrhages, caused by tiny bleeds in the nail bed capillaries. Minor trauma can produce them, and a single line is usually nothing to worry about. But when splinter hemorrhages appear on multiple nails at once without any obvious trauma, they can signal a systemic problem, most notably infective endocarditis (an infection of the heart valves), as well as vasculitis, lupus, or psoriatic arthritis.4Europe PMC. Splinter Hemorrhage If you notice these lines on several fingers or toes and you haven’t been doing anything physically rough with your hands or feet, it’s worth bringing up with your doctor.
Glomus Tumors
Rarely, a bluish or pinkish-red spot under the nail turns out to be a glomus tumor, a small benign growth arising from the glomus body, a structure involved in temperature regulation. The classic presentation is a triad of localized tenderness, severe pain, and cold sensitivity. These tumors are more common in fingers than toes, but they do occur in toenails. The pain is often out of proportion to the size of the spot, and cold exposure or even light pressure on the nail can trigger sharp discomfort.5Europe PMC. Glomus tumours of the hand: Review of literature If a small colored area under your nail has been hurting for weeks and gets worse in the cold, a glomus tumor is on the list of possibilities.
How to Tell a Bruise from Subungual Melanoma
The worry that keeps people searching online isn’t infection or glomus tumors; it’s melanoma. Subungual melanoma is a type of skin cancer that starts in the nail matrix (the tissue under the cuticle where the nail grows) and can look like a bruise or a dark streak under the nail. It’s uncommon in the general population, but it’s the scenario where missing the diagnosis carries the most serious consequences.
Roughly two-thirds of nail unit melanomas present as a longitudinal band of pigment running from the cuticle to the tip of the nail. This band is called longitudinal melanonychia, and it has a broad list of possible causes, melanoma being just one of them.6PubMed Central. Adult and Pediatric Nail Unit Melanoma: Epidemiology, Diagnosis, and Treatment That’s part of what makes diagnosis tricky: the same visual pattern can be harmless or dangerous.
Dermatologists use dermoscopy (a magnifying tool with a light source) to distinguish the two. In a study comparing subungual hematomas to melanomas, the hematomas showed a homogeneous color pattern in about 92% of cases, often with globular shapes and a fading edge toward the borders of the discoloration. Melanomas, by contrast, displayed irregular longitudinal bands, a triangular shape within those bands, a Hutchinson sign (pigment spilling onto the skin around the nail), and ulceration. In that study, features like Hutchinson sign and ulceration were found in all of the melanoma cases and none of the hematomas.7Wiley Online Library. Dermoscopy of subungual haemorrhage: its usefulness in differential diagnosis from nail-unit melanoma
You don’t need a dermoscope at home to watch for warning signs. A few features strongly suggest you should see a dermatologist rather than waiting:
- No injury history: You can’t recall any trauma to the toe, and the discoloration appeared gradually.
- A dark band rather than a blot: A streak of color running the length of the nail, especially if it widens over time.
- Pigment beyond the nail: Dark color spreading onto the cuticle or the skin around the nail (Hutchinson sign).
- Change over weeks: A true bruise gradually shifts position as the nail grows out. A melanoma stays anchored in place or gets darker and wider.
- Ulceration or bleeding: The nail bed breaks down, bleeds, or the nail starts separating from the bed without any new injury.
No single one of these features diagnoses melanoma on its own, but any of them should prompt a visit rather than a “wait and see.”
Why Some Dark Nail Bands Are Completely Normal
Longitudinal melanonychia, that pigmented stripe running down the nail, is extremely common in people with darker skin tones. A retrospective review at a tertiary nail center noted that nearly 100% of older Black individuals have some degree of longitudinal melanonychia, while the prevalence in White populations is around 1%.8CrossRef. A retrospective review of cases of longitudinal melanonychia referred to a tertiary nail centre over a 5-year period to identify the various subtypes and outcomes In these cases the pigment comes from normal melanocyte activation in the nail matrix, not from any disease process. It can appear on one nail or several, and it’s usually stable over time.
This creates a specific diagnostic challenge. If you have dark skin and notice a streak on a toenail, it’s probably benign melanonychia. But melanoma can still occur in this context, and subungual melanoma is proportionally more common in people with darker skin than other melanoma types. The features that should trigger concern are the same ones listed above: a band that widens, develops irregular edges, or spreads pigment onto surrounding skin. A stable, uniform band that’s been there for years and hasn’t changed is very different from a new or evolving one.
How Long It Takes for a Bruised Toenail to Grow Out
Once the blood is trapped under the nail, it isn’t going anywhere until the nail itself pushes it forward. Toenails grow at roughly 1.6 mm per month on average, and the big toenail grows a bit faster than the smaller ones.9Wiley Online Library. Growth rate of human fingernails and toenails in healthy American young adults A full big toenail is usually somewhere around 15 to 20 mm long, which means you’re looking at roughly 9 to 12 months for the discoloration to grow completely out to the free edge where you can clip it off. For smaller toenails, which grow even more slowly, the timeline can stretch even longer.
During that time the bruise will shift gradually toward the tip. You can use this movement as a diagnostic clue: if the dark area migrates forward over several weeks and the new nail growing in behind it looks clear and normal, you’re watching a bruise resolve. If the dark area stays fixed near the cuticle or new pigment keeps appearing at the base, the color isn’t from old blood and needs evaluation.
Some people lose the nail entirely after a severe hematoma. The blood separates the nail plate from the bed, and the nail eventually falls off. This looks dramatic but isn’t usually dangerous. A new nail will grow in from the matrix over the same multi-month timeline, though it may appear ridged or slightly irregular at first.
When and How a Subungual Hematoma Gets Treated
Most small hematomas don’t need any treatment. The discoloration is cosmetically annoying, but if the pain is tolerable and the nail isn’t lifting, the standard advice is to leave it alone and let it grow out. Icing the toe and keeping it elevated in the first day or two after injury helps with swelling.
Larger hematomas that cause significant throbbing pain are a different story. When the blood pocket is big enough to create serious pressure against the nail bed, a procedure called nail trephination can relieve it. A small hole is made in the nail plate, allowing the pooled blood to drain. In one reported case, controlled trephination using a specialized drill that penetrated the nail plate without breaching the nail bed produced substantial pain relief within eight hours.10PubMed Central. Controlled nail trephination for subungual hematoma Other methods use a heated needle or a small-gauge needle to create the drainage hole. The procedure is quick, and the pain relief is often immediate as the pressure drops.
Trephination works best within the first day or two after injury, while the blood is still liquid. After that, the hematoma begins to clot and can’t be drained as easily. If the nail has already lifted significantly from the bed, or if there’s concern about a fracture in the underlying bone (which can happen with crush injuries), your doctor may want to remove the nail entirely to inspect the nail bed for lacerations.
What Happens When a Biopsy Is Needed
If a dermatologist suspects the discoloration might be melanoma or another type of growth, the definitive next step is a biopsy of the nail matrix. Several techniques exist. A punch excision uses a small circular blade to remove a core sample. A lateral longitudinal excision takes a strip from the side of the matrix. A shave biopsy removes a thin layer from the matrix surface. Familiarity with all three allows the physician to choose the approach that best matches the location and size of the pigmented area.11PubMed Central. Nail matrix biopsy of longitudinal melanonychia: diagnostic algorithm including the matrix shave biopsy
A newer technique uses a COâ‚‚ laser to create a small window in the nail plate, giving direct visual access to the matrix underneath. Dermoscopy is used both before the procedure to select the biopsy site and during the procedure to examine the matrix tissue directly. In a series of eleven cases, this window technique established a diagnosis in every case without significant complications, identifying melanoma in situ in four cases and benign nail matrix activation in seven.12PubMed Central. A Novel Window Technique Using CO2 Laser, and a Review of Methods for Nail Matrix Biopsy of Longitudinal Melanonychia
Nail biopsies aren’t routine for every dark toenail. They’re reserved for cases where the clinical picture is uncertain, where the discoloration has worrying features, or where monitoring has shown a change over time. Your dermatologist will weigh the visual findings, your history, and your risk factors before recommending one.
Practical Steps for a Bruised Toenail at Home
If you’re fairly confident the discoloration came from an injury you remember, your main job is protecting the nail while it grows out. Keep the toe clean, wear shoes with enough room in the toe box so the nail isn’t taking additional hits, and trim the nail straight across to reduce the chance of it catching on something and tearing. If the nail lifts at the edges, a small bandage can keep it from snagging on socks.
Avoid painting over the discolored nail with opaque polish for months at a time. One reason is practical: you want to be able to check periodically that the dark area is migrating toward the tip. If new dark pigment keeps appearing at the base and you can’t see it through three layers of polish, you might miss a change that matters.
For athletes dealing with recurrent bruised toenails, prevention is more useful than treatment. Shoes should leave about a thumb’s width of space between your longest toe and the front of the shoe, and socks that wick moisture can reduce friction. Keeping toenails trimmed short helps too, since a long nail catches more force when it hits the shoe. If you’re a runner and the same nail keeps bruising despite good shoe fit, a sports podiatrist can evaluate whether your gait pattern is contributing.
Medications that thin the blood, such as warfarin or daily aspirin, can make subungual hematomas larger and slower to resolve from even minor bumps. If you’re on blood thinners and your toenails seem to bruise easily, that connection is worth mentioning to whoever manages your anticoagulation.
When Toenail Color Calls for Urgent Attention
Most bruised toenails are a nuisance rather than a danger. But a few scenarios warrant fast action rather than watchful waiting. If the pain after an injury is severe and increasing rather than fading, the hematoma may be large enough to need drainage, and there could be an underlying fracture. If the dark area appeared without any trauma, hasn’t moved with nail growth after a couple of months, and is getting wider or darker, a dermatologist should see it soon. Pigment spilling onto surrounding skin is one of the clearest red flags for melanoma. And dark streaks or discolorations appearing on multiple nails simultaneously, especially with other symptoms like fever, fatigue, or joint pain, could point to a systemic condition like endocarditis rather than anything local to the nail.
Children with dark nail streaks deserve a careful look, too. Although subungual melanoma in kids is rare, benign causes also tend to look slightly different in pediatric nails. A pediatric dermatologist can sort out what’s going on without unnecessary anxiety. For anyone of any age, the single most useful piece of home monitoring is taking a photo of the nail when you first notice the discoloration and comparing it every few weeks. A bruise migrates; a melanoma doesn’t. That simple observation is the best triage tool you have before walking into a clinic.