Subungual Hematoma: Causes, vs. Melanoma, Treatment, More

Quick heads-up: This article is educational and can’t diagnose anything. If you’re worried about a dark mark under a nailespecially without an obvious injuryget checked by a clinician (and ideally a dermatologist for suspicious nail changes).

What Is a Subungual Hematoma (and Why Does It Hurt So Much)?

A subungual hematoma is the fancy medical term for “blood trapped under your nail.”
It usually happens after a nail takes a direct hitthink: car door, dropped dumbbell, rogue hammer swing, or a toe that met a coffee table at full speed.
The blood gets stuck between the nail plate (the hard part) and the nail bed (the sensitive tissue underneath), creating pressure in a space that wasn’t designed to host a surprise pool party.
Result: throbbing pain and a nail that suddenly looks like it joined a goth band.

The good news? Most subungual hematomas are minor injuries that improve over days, even if the discoloration sticks around much longer as the nail grows out.
The “not as fun” news? Nail trauma can sometimes come with deeper issues like a nail-bed tear or a fracture, and a dark nail mark isn’t always just a bruise.
That’s where knowing the differencesespecially subungual hematoma vs. melanomamatters.

Common Causes (and the Usual Suspects)

Most subungual hematomas come from blunt force or crush injuries. But there’s another sneaky cause that catches athletes by surprise:
repetitive micro-trauma (aka “my shoes and my toenails are in an unhealthy relationship”).

Typical scenarios

• Acute trauma: slamming a finger in a door, dropping a heavy object on a toe, getting stepped on, or sports collisions.
• Repetitive pressure: long-distance running, hiking down steep hills, ski boots, tight cleats, or shoes that crowd the toes.
• Work-related mishaps: tools, lifting, machinery, and anything that makes you say, “I’m fine” while clearly not fine.

Risk factors that make it more likely

• Poorly fitting footwear (especially for runners and hikers)
• Sports with toe impact (soccer, basketball, trail running, dance)
• Jobs or hobbies involving heavy objects or tools
• Prior nail trauma (a previously injured nail can be more vulnerable)

Symptoms: What You’ll Notice First

A subungual hematoma tends to announce itself loudly. Classic signs include:

• Severe or throbbing pain (pressure under the nail is the main villain)
• Color change under the nail: red/purple early, then dark brown to black
• Tendernesseven light touch may feel rude
• Nail lifting if pressure builds enough to separate nail from nail bed

Over the next weeks, the dark area usually “travels” outward as the nail grows. That slow migration is an important clue when comparing a bruise under the nail to other causes of nail discoloration.

When It’s More Than “Just a Bruised Nail”

Most bruised nails can be managed conservatively, but some situations deserve prompt medical attentioneither because you may need drainage, imaging, or repair, or because the discoloration might not be a hematoma at all.

Get urgent care sooner (not later) if:

• Pain is intense or worsening over the next few hours
• The nail is split, partially ripped off, or there’s a deep cut
• You suspect a fracture (significant crush injury, deformity, inability to use the finger/toe normally)
• The dark area covers a large portion of the nail and is very painful
• After any drainage, you develop increasing redness, swelling, pus-like drainage, or fever

Subungual Hematoma vs. Melanoma: How to Tell the Difference

Let’s talk about the anxiety-producing elephant in the room: melanoma under the nail (often called subungual melanoma or nail melanoma).
It’s rare, but it’s seriousand it can look like a bruise or a dark stripe.
The goal isn’t to turn you into a DIY dermatologist; it’s to help you recognize when you should stop guessing and get evaluated.

What a subungual hematoma usually looks like

• Timing: Appears soon after a clear injury (minutes to hours)
• Pattern: Often a blotch or pooled dark area (can cover part or much of the nail)
• Pain: Common and may be throbbing early on
• Movement: The discoloration typically grows out toward the tip as the nail grows

What nail melanoma may look like (red flags)

Nail melanoma often starts in the nail matrix and can show up as a pigmented band (called longitudinal melanonychia) or irregular pigment under the nail.
Warning signs that merit a dermatology visit include:

• A new dark streak/band (brown/black), especially on a single nail
• Pigment spreading onto the surrounding skin near the nail (a classic warning sign clinicians look for)
• Nail splitting, lifting, or a persistent bump under the nail
• No clear injury (or the mark doesn’t behave like a bruise afterward)
• Doesn’t migrate outward with nail growth or seems to widen/darken over time

A practical “bruise test” you can do at home

You don’t need a microscopejust patience and a phone camera.
Take a clear photo today, then compare weekly.
A bruise tends to move forward (away from the cuticle) as the nail grows.
If the pigment seems “anchored” near the cuticle, expands, or shows skin staining around the nail, it’s time to book an appointment.

Diagnosis: What a Clinician Looks For

Diagnosis is often clinicalmeaning the provider looks at the nail, asks what happened, and checks for associated injury.
They’ll typically assess:

• The nail plate and nail folds (edges where nail meets skin)
• Sensation, circulation, and movement of the finger/toe
• Whether the nail is intact or there’s a tear/avulsion
• Whether an underlying fracture is possible (sometimes an X-ray is recommended after a crush injury)

If there’s concern that the dark mark isn’t a simple hematomaor if melanoma is on the differentialreferral to dermatology may be recommended.
Nail melanoma diagnosis typically requires expert evaluation and, when indicated, biopsy.

Treatment: What to Do (and What Not to Do)

At-home care for mild cases

If pain is manageable and the nail looks intact, supportive care can be enough:

• Ice (wrapped in cloth) for swelling and discomfort
• Elevation for throbbing
• Over-the-counter pain relief if you can take it safely
• Protect the nailavoid pressure, and don’t “test” it by poking it every five minutes

When nail drainage (trephination) helps

If pain is intense and caused by pressure from pooled blood, a clinician may recommend nail trephinationcreating a tiny hole in the nail plate to let blood escape.
When it’s appropriate, this can provide fast relief (the “oh wow, I can breathe again” momentexcept it’s your fingertip).

Trephination works best soon after injury (often within the first day or two). After that, the blood can clot and drainage may be less effective.
It’s generally intended for simple hematomas where the nail is still attached and not badly torn.

Please don’t DIY this

The internet loves “life hacks.” Your nail bed does not.
Attempting to drill, burn, or puncture your own nail increases the risk of infection and further injuryespecially if you misjudge depth or sterility.
If you think you need drainage, get it done in urgent care, the ER, or a clinic where sterile technique and proper assessment are available.

When more extensive treatment may be needed

If the nail is split, partially avulsed, or there’s a laceration extending into surrounding skin, clinicians may need to remove part or all of the nail plate to evaluate and repair the nail bed.
This is also more likely if there’s significant crush injury, suspected nail-bed damage, or a fracture that changes management.

Recovery Timeline: How Long Until It Looks Normal Again?

Pain usually improves within days (and can improve immediately after successful drainage).
The discoloration, however, is on nail-time, not human-time.
You’ll typically watch it creep outward as the nail growsslowly, stubbornly, and with the persistence of a glitter spill.

• Fingernails: Often clear faster (commonly on the order of months).
• Toenails: Often take longer (sometimes close to a year for full grow-out).

It’s also common for the nail to loosen and even fall off weeks after a significant hematoma. A new nail usually grows in underneath.
If the nail bed was damaged in the original injury, the regrown nail may have ridges or mild deformity.

Prevention: Keep Your Nails Out of the Danger Zone

You can’t bubble-wrap your hands and feet forever (although some of us have considered it).
But you can reduce your risk:

• Wear properly fitting shoes, especially for running and hiking (room in the toe box matters).
• Trim nails straight across and not too shortoverly short nails can be more vulnerable.
• Use protective gear for manual labor (gloves, sturdy shoes/boots).
• Be mindful with doors and drawersthey’re undefeated.
• For runners: consider lacing techniques to reduce toe slam, and size shoes appropriately for downhill miles.

FAQ: Fast Answers to Common Questions

Is a black toenail always a subungual hematoma?

No. Trauma is common, but dark nail discoloration can also come from pigment bands, infections, benign growths, or (rarely) melanoma.
If you don’t remember an injury, or if the mark doesn’t grow out, get evaluated.

Will I lose the nail?

Sometimes. Larger hematomas can cause the nail to separate and shed weeks later.
A new nail typically grows in, though nail-bed injury can affect how smooth the new nail looks.

Should I get an X-ray?

After a significant crush injuryespecially with severe pain, deformity, or limited functiona clinician may recommend imaging to check for a distal phalanx fracture.
This is a judgment call best made in-person.

Can subungual melanoma be painful?

It can be, especially later on if there’s nail splitting, lifting, inflammation, or a growing lesion.
But pain (or lack of it) isn’t a reliable way to rule melanoma in or outpattern and behavior over time matter.

Conclusion: The Takeaway You’ll Actually Remember

A subungual hematoma is usually a straightforward story: nail gets whacked, blood gets trapped, your fingertip files a complaint.
With basic care, pain improves quickly, and the discoloration grows out over months.
But if the nail is torn, pain is severe, a fracture is possible, infection signs appear, or the pigment doesn’t behave like a migrating bruisedon’t tough it out. Get checked.
And when the question is “bruise under nail vs. melanoma?”err on the side of a professional opinion. Nails are small, but the stakes can be big.

Experiences & Real-World Scenarios (Common Stories People Share)

If you’ve never had a subungual hematoma, congratulations on your unusually peaceful relationship with doors, drawers, and gravity.
For everyone else, here are common experiences people describeand what they often learn along the way.

1) “The Door Slam Classic”

This one starts with a totally normal day, followed by a door that closes like it’s trying to win an argument.
Within minutes, the nail turns red-purple, the fingertip throbs, and suddenly you understand why people invent new words after injuries.
Many people try ice and elevation and do okayuntil the pressure ramps up.
A frequent comment after clinical drainage is some version of: “I should’ve done that sooner.”
The relief can be dramatic when pressure is the main cause of pain.

2) “Runner’s Toe: The Slow-Burn Surprise”

Runners often notice a dark toenail after a long run or racesometimes without a single “ouch” moment.
The discomfort may be mild, but the nail looks like it lost a bar fight.
The biggest aha moment here is footwear: toe-box space, sock choice, and downhill mileage matter.
People commonly report the toenail eventually loosening and shedding weeks later.
The second aha moment: toenails take their sweet time growing out, so the cosmetic reminder can linger long after the medal photo.

3) “The DIY Temptation (a.k.a. Paperclip Theater)”

A lot of people admit they Googled “drain blood under nail at home” while staring at a throbbing fingertip.
It’s understandablepain makes everyone resourceful.
But the common experience is that DIY attempts either don’t work, hurt more, or introduce new problems (like infection risk or nail-bed injury).
People who choose clinical care often mention how quick and controlled the procedure feels compared to the anxiety spiral of doing it themselves.
The lesson: if you think you need drainage, you probably also need someone trained to confirm you’re a good candidate for it.

4) “Wait… Is This Melanoma?”

This is the experience that sends people down a late-night search rabbit hole.
It usually happens when there’s no clear injury, the mark looks more like a band than a blotch, or it doesn’t seem to move as the nail grows.
Many people describe taking photos, comparing week to week, and realizing the pigment isn’t migrating outward.
That’s often the moment they schedule a dermatologist visitsometimes for reassurance, sometimes for further evaluation.
Even when it turns out to be benign pigment, people commonly say they’re glad they didn’t ignore it.
The takeaway isn’t “panic”; it’s “pay attention.” Nails change slowly, and so do the clues.

5) “The Healing Phase: A Lesson in Patience”

A recurring theme is surprise at how long discoloration lasts.
Pain often improves fast, but the nail can stay visibly bruised for weeks or months.
People also report that the color changes over timepurple to brown-blackand the clean nail gradually appears near the cuticle as growth continues.
This can be reassuring: growth usually means “bruise behaving like a bruise.”
If the dark area stays put, spreads to surrounding skin, or the nail becomes increasingly distorted, that’s when people tend to seek reevaluation.

Bottom line: most subungual hematomas are inconvenient, ugly, and painfulbut not dangerous.
The real-life win is knowing when to use simple care, when to consider drainage, and when to treat a nail change as a “get this checked” signal instead of a cosmetic annoyance.

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