I’ll never forget the first time I lost a toenail.
It was after a long, sweaty 12-miler in the middle of summer.
I peeled off my sock and there it was: my big toenail, black as oil, throbbing like it had its own pulse.
Blood in the toe box.
Sock ruined.
Nail eventually fell off.
And here’s the kicker—I knew I should’ve trimmed my nails the night before. Big mistake.
But hey, I was tired.
Figured it could wait.
It couldn’t.
At the time, I weirdly wore it like a badge of honor. “I’m a real runner now,” I thought. Like a lost toenail was some war trophy.
Turns out, it was just a sign I was being careless.
Since then, I’ve heard the same story from all types of runners—weekend warriors, 5K newbies, ultra vets.
Let’s dive deeper into this annoying but not so dangerous running ailment.
What Is Runner’s Toe, Anyway?
Here’s the deal. That black nail? It’s basically a bruise under the toenail—called a subungual hematoma if you want the science.
Most runners call it “runner’s toe.”
It happens when your toe keeps banging against the front or top of your shoe, over and over.
Every footstrike adds up, and those little hits break tiny blood vessels under the nail.
The blood gets trapped. That’s the dark color you see—red, purple, black.
Imagine gently tapping your toenail with a hammer 10,000 times.
Eventually, it’s gonna protest.
Runner’s toe is super common if you’re doing long runs, downhill work, or trail miles where your foot’s shifting around a lot.
The big toe and second toe usually take the beating, especially if they’re the longest.
Good news: It’s usually not serious. Just ugly and annoying.
The nail might hurt for a bit, change colors like a bad bruise, maybe fall off. Then it grows back. Slowly.
But here’s the catch—if you ignore it and let bacteria sneak under that loose nail in a hot, sweaty shoe? Now we’re talking infection territory.
That’s where things can get nasty.
Most of the time, though, podiatrists will tell you it “looks worse than it is.”
And I agree—unless you let it fester. Then you’ve got problems.
Why Runners Get Black Toenails
Let’s cut the fluff and get into what’s actually causing your toe to turn into a horror movie scene.
1. Shoes That Don’t Fit Right
This is the big one. And 9 out of 10 times, it’s the reason your toe’s taking a beating.
Too tight? Your toes are getting slammed into the front of the shoe every time you land.
Too loose? Your foot slides forward and still smacks the front.
Either way—impact city.
When I got my first black nail, I realized I was wearing the same size in my running shoes as my casual sneakers.
Not a good idea.
Running shoes need room—your feet swell, your toes need wiggle space.
Rule of thumb (literally): you should have a thumb’s width of space between your longest toe and the front of the shoe.
And the toe box should be roomy enough that your toes aren’t pinched from the sides.
Oh, and don’t forget heel lockdown.
If the back of the shoe is loose, your whole foot shifts forward on every downhill. Boom—toe slam.
When I got into running, I used to suffer from constant blood blisters under my big toes, especially after a long run. But when I finally sized up a full shoe size and—no surprise—the problem disappeared.
Some brands are better for toe space too.
Altra, for example, is popular among trail and ultra folks because the foot-shaped toe box gives your toes room to breathe.
No more cramming them into a pointy wedge.
2. Dead Shoes That Should’ve Been Retired
Even if your shoes fit great when new, they don’t stay that way forever.
Old shoes lose their shape, cushioning, and internal structure.
That includes the toe bumper up front. If that gets crushed down, there’s less padding between your nail and the outside world.
If your shoe’s got 400+ miles on it, the fit might’ve changed just enough to start causing problems—especially on longer runs.
3. Downhills + Overstriding = Toenail Carnage
If you’ve ever finished a hilly race and peeled off your socks to find one of your toenails black or halfway gone… welcome to the club. Downhill running is one of the fastest ways to destroy your toenails.
Here’s why:
Every step downhill, gravity is doing its thing—sliding your foot forward in your shoe and jamming your toes into the front like battering rams.
And if your form breaks down and you start overstriding (landing too far out front), you’re basically hitting the brakes with every stride and driving your nails into the shoe over and over.
One podiatrist from Cleveland Clinic straight-up said runner’s toe is caused by your toenail “repeatedly and forcefully” hitting the shoe. And guess what ramps that up? Descents.
4. High Mileage = More Chances to Wreck Your Nails
You don’t need to be running mountains to mess up your toenails—sometimes, it’s just the sheer mileage that does it.
More miles = more steps = more mini toe-bashes.
A runner-doc once told me: “You probably won’t get black toenails running 10 miles a week. But start hitting 40, 50, 60 miles? It’s almost a rite of passage.”
Why? At higher mileage, your feet swell.
Your shoes stay moist.
Your toes take thousands more micro-hits.
That’s a recipe for bruised nails—especially if your shoes are even slightly tight or your socks don’t manage moisture well.
In fact, research shows that running 30–40+ miles per week increases your risk for various injuries.
The study didn’t zero in on toenails, but I can tell you from coaching experience: every marathon build-up, someone in the group starts complaining about a black nail.
It’s usually the first clue we need to check their footwear.
The warning sign: one or two black nails popping up after mileage spikes.
Not always a dealbreaker, but definitely a sign to check your shoes, socks, and stride.
5. Cotton Socks & Bad Shoes
You could have perfect form and a smooth stride, but if your socks and shoes suck, your toes are still in trouble.
Let’s start with socks: if you’re still running in old-school cotton socks, we need to talk.
Cotton holds moisture like a sponge.
That wet environment softens skin and makes your feet slide more inside your shoe—add in the friction, and you’ve got a toe-pounding mess.
Plus, soggy feet = blisters = more toe trauma.
Go for moisture-wicking socks—synthetic blends or merino wool. These keep your feet dry and reduce slippage.
And don’t assume thicker is better. Thick socks in a snug shoe might crowd your toes even more.
Always test your race-day shoes with your race-day socks.
Now the shoes: worn-out midsoles, too-small toe boxes, or stiff non-running footwear are all red flags.
6. Long Toenails: The Silent Toe Killer
Let me be real with you—if you’re out here running with long toenails, you’re asking for it.
I’ve done it. And paid the price.
We’re talking black nails, bloody socks, and pain that makes every step feel like your toe’s in a vise.
When your toenails grow past the tip of your toe, they don’t just look gnarly—they become weapons.
Every step you take, that nail jams into the front of your shoe, and it doesn’t take long before your nail starts to lift, bleed underneath, and turn into a full-blown horror scene.
Here’s what I’ve learned: keep your toenails trimmed flush with the end of your toe. Not freakishly short, but short enough that your actual toe—not the nail—is taking the hit inside the shoe. That one little detail can save you from a whole world of pain.
And yeah, I know it sounds a little bougie, but nowadays I wear by regular pedicures —just to keep the nails in check. You don’t need to hit a spa, but grab those clippers once a week.
Straight across trim, no crazy curves at the corners (unless you like dealing with ingrown nails). And don’t forget to file any sharp bits. I’ve skipped a trim before a long run and ended up with a black nail overnight. Never again.
Oh—and bonus: clean, short nails mean fewer foot funk problems too. Fungal infections love long, dirty nails. Just sayin’.
Spotting Runner’s Toe Before It Gets Ugly
Black toenails don’t start out dramatic. It sneaks up on you.
One day your toe’s fine, the next it looks like a crime scene.
That Creepy Color Change
The first red flag? Discoloration.
I’m talking deep red, dark purple, greenish-black… not normal toe stuff.
This is blood pooling under the nail—what docs call a subungual hematoma. At first it might just look like a dark smudge. Then it grows. If you’ve ever had one, you know the dread.
The color won’t fade like a regular bruise because it’s stuck under the nail. And no, pressing on it won’t turn it white—it’s not on the skin surface. That’s one way to know it’s the real deal.
Now, if you see black or brown streaks in your nail and you haven’t whacked your toe or done a long run recently? Get it checked. It’s rare, but melanoma can show up in the nail.
But if you just finished a 10-miler and your toe turned black? Yeah, it’s almost always a running war wound.
That Nasty Pressure Throb
Sometimes you don’t even feel it during your run. But a few hours later? That nail starts to throb like it’s got its own pulse.
According to the American Osteopathic College of Dermatology, that pain is from blood pooling and creating pressure under the nail.
Tap it gently. If you wince? You’ve got a problem brewing under there.
Some runners can walk it off.
Others can barely get their shoe back on.
Pain peaks in the first 24–48 hours, then usually eases off—unless the pressure builds up so bad the nail lifts.
That’s when it gets gnarly.
Nail Lifting (AKA: The Gross Part)
If the damage is deep enough, your nail can start to lift off the bed.
It might not be right away—you’ll see signs over time. Like the edge of the nail separating, or a bubble forming underneath it.
WebMD says if there’s enough blood trapped under there, the whole nail might eventually fall off.
I’ve had this happen, and it’s both disgusting and weirdly satisfying (don’t judge). It usually takes a few weeks, once new nail starts growing underneath.
If you notice the black spot covers most of the nail, or you can wiggle the nail and it feels loose, don’t rip it off.
Seriously.
I know it’s tempting.
But tearing it can scar the nail bed—and the new nail might grow back thick, warped, or not at all.
Let it come off naturally, or ask a doc to trim it if it’s just barely hanging on.
Signs of Infection: When That Black Toenail Goes Rogue
So, you’ve got a black toenail. Welcome to the club.
Most of the time, it’s just gross-looking and annoying.
But sometimes? It turns into something a little more serious.
If bacteria sneak under the nail—especially if it’s partially lifted or you tried a DIY drain job with a safety pin and a prayer—you’re at risk of infection.
That’s when runner’s toe stops being a badge of honor and starts being a problem.
Here’s what to look out for:
- Redness and swelling that gets worse, not better
- Throbbing pain that cranks up a few days later
- Warmth, ooze, or pus under or around the nail
- That gross, sour-smelling funk (you’ll know it)
- In bad cases? Fever or red streaks up your foot—rare, but serious
Can You Run with a Black Toenail?
Short answer: Yeah, usually.
Long answer: It depends on how bad it hurts.
If it’s just a little sore or ugly-looking but not really affecting your stride, you’re probably good to go.
Dr. Jordan Metzl (sports doc who’s seen it all) says, “If it doesn’t hurt too much, you should be fine to run.”
And I agree. I’ve run with more black toenails than I can count. A little tape, a thick sock, maybe a toe sleeve—and I’m out the door.
Pro tip: Trim the nail short so it doesn’t snag your sock. And if it’s tender? Pad it. I’ve even cut a hole in the top of an old shoe mid-race just to give my toe some breathing room. Ultra-runners do it all the time.
How to Treat a Black Toenail from Running
So you’ve got one. Now what?
When You Don’t Need a Doctor
- Nail’s just dark? No biggie. It’ll fall off eventually, and a new one will grow.
- Mild pain? Ice it, tape it, and carry on.
When to See a Doctor
Sometimes you gotta wave the white flag and let a pro step in:
- Throbbing pain that won’t quit: If your toe feels like it’s pulsing with each heartbeat, it might need to be drained. That blood trapped under the nail is building pressure. Doctors do a quick drain (called trephination), and relief is almost instant.
- Signs of infection: Red, hot, swollen, leaking pus? That’s serious. You’ll need antibiotics and maybe the nail removed.
- Nail’s 75% black and ballooning: That much trapped blood usually means a doc should take a look. You might save the nail—or not—but the pain’s gotta go.
- Not sure it’s just trauma: If you didn’t stub it or jam it during a long downhill and one random nail turns black, it’s worth letting a doctor rule out other stuff like fungal infection—or, rarely, something worse like melanoma.
- If you have diabetes or circulatory issues: Any foot injury is a bigger deal. Don’t wait—get seen.
When you do see a doc, they’ll likely poke a tiny sterile hole to drain the blood. If the nail is dangling, they may remove it cleanly so a new one can grow in straight.
They might slap on an antibiotic ointment or give you pills if it’s infected. Quick, easy, and worth it if you’re in legit pain.
Home Treatment for Mild Black Toenails
Let’s be real—if you’ve been running long enough, black toenails are almost a badge of honor. Ugly? Yeah. Painful? Sometimes. But scary? Usually not.
If the pain’s minor and the nail just looks bruised or a bit weird, good news: you probably don’t need to panic or hit the doc’s office.
Most mild cases are easy to treat from your own bathroom floor—just be smart and don’t rush it.
Here’s what to do:
Rest & Put Your Feet Up
Give that toe a break. Take a couple of days off from pounding pavement—especially if it hurts to walk.
Elevating your foot when you’re chilling can help kill the throbbing. Less blood rushing down = less pressure = less pain.
Ice It (But Don’t Go Overboard)
The first day or two, ice can be your best buddy.
Wrap some in a towel or use a cold can of soda (seriously, it works), and give that toe 15–20 minutes of chill time. Don’t slap ice directly on bare skin unless you want frostbite to go with your bruised nail.
Painkillers, If Needed
Ibuprofen’s great for knocking down swelling and pain. Acetaminophen works too if you’re just trying to dull the ache. Use whatever you’d take for a sore back or a headache—but follow the directions, yeah?
Keep It Clean & Dry
This isn’t the time for sweaty socks and dirty locker room floors.
Wash the foot daily, especially around the nail. If the nail’s lifted a bit, squirt some antiseptic (like iodine or alcohol) around the edges to keep the funk out. On your runs, cover it with a bandage, then let it air out after.
Don’t Torture the Nail More
Loose nail? Don’t yank it. Seriously. Trim off any bits that are totally unattached so they don’t snag, but let the rest ride.
Wear open-toe sandals or shoes with plenty of toe room—your foot deserves some breathing space right now.
Usually, the pain fades after a couple of days, and you’ll be fine to lace up again soon.
The nail might look gnarly for weeks (or months), but as long as there’s no pain or infection, you’re good to train again.
Just keep tabs on it. If something starts feeling worse instead of better, don’t tough-guy it—get it looked at.
DIY Drainage (AKA the Sketchy Part—Be Careful)
Alright, this next bit? It’s not for the faint of heart. Or anyone squeamish. But hey, runners are a gritty bunch.
Sometimes the pressure under a black toenail builds up like a balloon.
If you can’t get to a doc, and it’s really painful—like pulsing, can’t-sleep kind of pain—some runners drain it themselves. I’ve done it.
Others have too.
Doesn’t mean you should. Infection’s a real risk here. But if you’re gonna do it, here’s how to not completely screw it up:
- Sterilize your weapon of choice. Needle, safety pin, unfolded paperclip—whatever you use, burn it till it’s red-hot or soak it in alcohol. If it’s not sterile, forget it.
- Find the darkest spot. You’re going through the nail plate—not the skin below. That’s key. You want to pierce the area where the blood’s pooled.
- Go slow. Use the heated paperclip to burn through the nail (yep, that’s a thing), or twist the needle slowly until… POP. Blood might start oozing out. Could be a little, could be a horror show. Either way, once the pressure’s gone, the relief is often instant.
- Clean it up. Press gently to drain the rest, wipe with sterile gauze, then hit it with antiseptic. Bandage it and keep it wrapped for a few days. Change that dressing daily, and don’t ignore signs of infection (redness, pus, nasty smell).
- Respect the aftermath. You just made a hole in your body, so treat it like one. Keep it clean, cover it up for runs, and don’t expect miracles. That nail’s probably still gonna fall off. You just gave it a head start.
And for the love of feet, don’t use a power drill. Someone once told me they tried that. Don’t be that guy.
What Happens Next? The Long Road to Normal (Sorta)
Once the pain’s under control and there’s no infection, your next question is probably: “What now?” Well, the ugly truth is… the nail’s probably toast.
Nail Fall-Off Timeline: 1–3 Weeks (Give or Take)
If the bruise under the nail was big, the connection at the base is likely shot.
Within a week or two, you’ll notice it loosening—maybe catches on socks, maybe starts to lift. Sometimes, a new nail starts growing underneath and slowly pushes the old one off.
I’ve had one take a month to finally pop. Another one bailed after two weeks. Everyone’s feet write their own story.
Rule of thumb: Don’t rip it. If it wants to leave, it’ll leave. Until then, keep it clean, tape it down during runs, and trim any snags.
But What If It Stays Put?
Lucky you.
If the bruise was small or shallow, the nail might not fall off at all—it’ll just grow out over time.
You’ll watch that black spot move up the nail month by month like some kind of slow-motion scar.
Eventually, you’ll clip it away and be done with it. Best-case scenario, honestly.
New Toenail? Don’t Hold Your Breath.
Alright, real talk — toenails grow slower than a long run with dead legs. If you’ve ever lost a toenail (hi, marathon training), you already know: it’s not coming back anytime soon.
We’re talking 6 to 18 months for a full toenail regrowth.
Yeah, you read that right — a year or more for the big toe. Smaller toes are a bit quicker, but still slow.
Fingernails? 4 to 6 months.
Toes? Grab a snack. It’s a long ride.
I lost my big toenail after Mantra 166 Trail race in East Java, and it took close to 8-9 months before it looked like a toenail again — and not some zombie horror prop.
While your body’s working behind the scenes to rebuild it, you’ll notice some changes: the skin underneath (the nail bed) starts to thicken and toughen up.
That’s your body throwing down some natural armor.
When the nail starts growing back, it might be thinner, ridged, or even look a little off. Don’t panic — that’s normal. It strengthens up over a few trim cycles.
Sometimes It Grows Back… Funky
Let’s be honest — that new nail might look like it came back from war. It’s not always pretty. After trauma, it’s pretty common for the first regrowth to be:
- Thicker
- Bumpier
- Curved weirdly
If you yanked the nail off too aggressively or wrecked the nail matrix (the growth zone), you might have a permanent ridge or odd shape.
Dr. Botek says tearing a nail can scar the nail bed, and yeah — the nail may never grow back exactly the same.
Been there. After one nasty subungual hematoma (that’s the gross blood blister under the nail), my toenail came back like it had armor plating. Stayed that way for a year, then finally chilled out.
Quick PSA: Keep the area clean while it’s regrowing. Fungal infections love damp, damaged nail beds — and they’ll leave your new nail thick, yellow, and gnarly.
Some of us just accept the gnarly. If your toenails look like they’ve been through combat, you’re not alone. Calluses under the nail, weird edges — they’re mostly cosmetic. If it bugs you, a doc can grind it down or treat for fungus. But if it’s not hurting? Just roll with it.
Dean Karnazes (yep, the ultrarunning legend) once said:
“Toenails are overrated.”
He’s not wrong.
No Toenail? You Can Still Run
This might surprise you — you don’t actually need a toenail to run. I’ve run plenty of miles with nothing on the big toe but tough skin. Once it doesn’t hurt, you’re good to go.
Some runners even have chronic toe issues and choose to get the nail removed permanently. Extreme? Maybe. But if that nail keeps falling off every race season, I get it.
Point is — don’t obsess. Your body knows what it’s doing. That new nail will grow in on its own schedule. All you’ve gotta do is protect it, keep your shoes dialed in, and be patient.
Final Word from Coach Dack: Black Toenails Ain’t a Badge
After pounding pavement for over 15 years — and losing more toenails than I care to admit — I’ve finally stopped treating black toenails like battle medals. Yeah, I used to think they meant I was tough. “Look at me, real runner stuff!” But truth is? They’re not a badge. They’re a signal. And usually, they’re your feet yelling, “Yo! Something’s off!”
Here’s the real talk: black toenails are preventable. And no, I’m not saying you’re soft if you get one. It happens. But don’t wear it like it’s something to celebrate either. Like I tell my runners all the time — pain isn’t proof of progress. It’s feedback. And if your nail turns purple and dies? That’s feedback you can’t ignore.
Maybe your shoes are too tight. Maybe you’re bombing down hills with sloppy form. Or maybe those toenails are long enough to carve a turkey. Whatever the reason, that little mess under your sock is a coachable moment.
What to Do Instead? Run Smart, Not Bloody
Want to keep your toenails? Cool — then here’s what you do:
- Size up your shoes: You want enough toe room, especially for downhills.
- Trim your nails: Don’t let ‘em dig in.
- Sock game matters: Look for blister-free, sweat-wicking socks that don’t bunch.
- Fix your downhill form: Lean slightly forward, keep your cadence up, and control the descent.
When you do that stuff right, your toenails stay pink and boring — just how we like ’em.
If You’ve Got One Now…
Got a black nail right now? First off — respect. You earned that gnarliness. It’ll fall off eventually, and yeah, it’ll look gross for a bit. But you’ll live. Just don’t let it happen again if you can help it. Learn from it. Adjust.
Use it as part of your runner war stories:
“Remember that race where my nail came off at mile 12 and I kept going?”
Classic. Just… aim for it to be the last time you tell that story firsthand.
Got a Toenail Tale? Let’s Hear It.
Look, runners are a strange and resilient tribe. If you’ve got a horror photo, a clever hack, or a toenail prevention trick that saved your soles — drop it in. I’ve heard everything from duct tape wraps to silicone toe caps and even DIY toenail rituals worthy of a garage horror movie.
We share this stuff not to brag about pain — but to stay in the game longer. Stronger. Smarter.
Wrap It Up: Keep the Toenails, Skip the Drama
I get it — losing a toenail can feel like part of the runner rite of passage. But the truth is, your best runs happen when your feet aren’t screaming at you. Trust me. It’s way more hardcore to line up healthy and ready than limping through with bandaged toes and bloodied socks.
Take care of your feet. Stay one step ahead. And remember, toenails might be overrated… but not having to explain your missing one every time you wear sandals? That’s the real win.
Keep running strong — and may your toenails stay boring as hell.