Bruised Toenail: Causes, Treatment, and How to Run Again

Finishing the Chicago Marathon I expected my legs to hurt, but I was unprepared to find that taking off my shoe was extra painful due to a bruised toenail from running. In other words, a black toenail!

In two decades and 9 marathons this was a first for me!

It didn’t make me thing “now I’m a real runner”. I know that for many runners, it’s a sign they’ve pushed hard and feel like a bad ass.

But I was thinking “dang it, I’ve always done things to avoid this“! And again, it provided another chance to learn something new and improve on what I was doing.

Let’s start with this, runner’s toe is not required to be in the club and not something that you MUST endure.

Beyond slapping some shoes on your feet, they rarely get the same level of care and attention we provide to our knees and hips. But those toes are working hard with every step and once you’ve dealt with a broken toe while running or a bruised toenail, suddenly they feel far more important.

In this article, we’ll discuss everything you need to know to deal with a black toenail form walking or running. More importantly, with what you can do to prevent it from ever happening to you as a runner. And finally, how to treat it if you have it at this very moment.

Black Toenail from Running

The name itself tells you what we’re looking for. A toenail that now looks bruised and is often very sensitive to touch, including simply pulling on socks.

The area under or around the toenail turns dark purple or black, which is called a hematoma or bleeding under the toenail. It most often occurs when your toe repeatedly slams into your shoe or rubs against it.

While it can happen to any toe, we see it most in the longest toes which are more likely too be crowded in the shoe: big toe and second toe. The impact of the toe hitting the soft interior of the shoe, cause a microscopic amount of damage each time.

Since running is a repetitive sport, this results in repetitive trauma. And these microtraumas eventually add up leading to bleeding under your nail, which then starts to look black.

Black Toenails from Running

Medically, this condition is known as subungual hematoma. Subungual literally means under the nail, while hematoma means a collection of blood outside of blood vessels.

Common Causes of Bruised Toenails in Runners

As mentioned above, the most common cause of bruised toenails in runners is the repetitive pressure from the running shoe. This pressure is exacerbated by running on hard surfaces, running downhill, and running long distances without proper footwear.

Wrong Shoes (size or support)

Plus, inadequate foot support can cause excessive movement in the feet, which can also contribute to the development of bruised toenails.

Toenail Trimming

Another potential cause of bruised toenails in runners is improper toenail trimming. If toenails are trimmed too short or at an angle, it can cause them to dig into the surrounding skin and tissue, leading to bruising. It is important to trim toenails straight across and not too short to avoid this issue.

Foot Issues

Plus, certain foot conditions such as hammertoes or bunions can also increase the likelihood of developing bruised toenails while running. These conditions can cause the toes to rub against the inside of the shoe, leading to increased pressure and potential bruising.

Infections

In rare situations, a black toenail can also be caused by fungal infection, chronic ingrown nails, diabetes, or malignant melanoma, which is a type of skin cancer.

Identifying a Bruised Toenail

If you suspect that you have a bruised toenail, there are a few key symptoms to look out for. The affected toe may appear swollen, red, or black and blue in color.

You may also experience pain, discomfort, or sensitivity when walking or running. In severe cases, the toenail may even detach from the nail bed.

If you are experiencing any of these symptoms, it is important to take action to treat the injury. Ignoring a bruised toenail can lead to more serious complications, such as infection or permanent damage to the nail bed.

Keep an eye out for signs of infection

In general, this is more of a nuisance injury than one that requires medical intervention. But as with any bleeding we want to pay attention to the area and take action if needed.

This pain might feel more severe to some people suffering from runner’s toe, depending on the amount of pressure that’s building up under the toenail from the bleeding.

If even after two to three days you’re still experiencing a lot of pain and swelling, it could be a sign that your toenail is infected.

Signs of an infection:

some bad smell
oozing pus
along with the sharp pain
swelling
possible fever because of an infection

If you’re experiencing all these symptoms, then it’s time to head to the doctor straight away.

7 Tips to Prevent Bruised Toenails from Running

The repetitive nature of running as a sport really contributes to how much more likely runners are to suffer some bruised toenails. But it can also happen to walkers, hikers, triathletes and cyclists whose foot is pushing in to the front of the shoe.

The foot is moving in your shoe with every single stride you take, and the foot is producing tremendous force into the ground.

1. Larger Toe Box

A too-tight toe box means that with each step the shoe is compressing the top of the foot, which often leads not just to toe issues, but top of foot issues.

In fact, my Chicago marathon issue was exactly this. I had worn the Saucony Endorphin Pro for long runs up to 18 miles, but always in cool weather.

Once we hit Chicago where it was 80 degrees and humid, the swelling in my feet increased and without enough room in the toebox, my toe began to hit the top of the shoe with every single stride.

✅This is one reason many runners have found success with Altra Running shoes and their foot shaped toebox.

Checkout my list of the best wide toe box running shoes >>

2. Correct Shoe Sizing

Just like a too small shoe is going to squish your toes, a too large shoe allows for too much movement of your foot. This can easily lead to issues like blisters as well.

I’ve provided a detailed article on how to tell if your shoe fits properly, but some basics:

Being able to place a thumbwidth in front of your longest toe to the end of the shoe
No pinching or tightness across the top of your foot
Foot isn’t moving around a great deal with each step

Changing the way you lace your running shoes can often have a big impact. So before you give up on them, checkout those different techniques to see what might help.

3. Downhill Padding

Downhill running also presses the foot forward in the shoe, which is going to increase total pressure no matter how well your shoe fits.

If you’ll be doing a downhill race then, I recommend Toe Caps or pads.

What are toe caps?

The big thing is to ensure you don’t create new problems by adding bulk to your shoe or rubbing on other toes creating pain or blisters.

Pro-Tec is one of the most commonly recommended silicone gel toe caps, likely because it’s thin.
You don’t want to wear them on all toes, so pick the ones you most often have issues with (usually a big toe for downhills or if you have a longer toe).
Some folks like to wear these with the Injini toe socks for a little added comfort that they will stay firmly in place.
Definitely look at sizing – I haven’t tested these but I know sizing is one thing to consider when getting a good fit (i.e. do they have Big toe vs other toe options like Zen Toes).

toe caps for running

4. Keep Toenails Short

While there’s barely enough of a toenail for me to bother with a pedicure, my feet remain tremendously happier with very short toenails.

A longer toenail could be hitting the front of your shoe, which is then putting pressure on the toenail with each step you take. It’s important to cut the nail straight across to prevent ingrown toenails.

You can also happily get a pedicure asking them to go short and see exactly how the nail looks for your own future trimming.

5. Invest in Good Running Socks

Another area that so many of us try to skimp on when we start out is socks. I mean $15 for a pair seems insane.

Until you have a foot issue and realize you can’t even get your shoe on without pain, then they’re worth every penny.

Yet again, the process of helping to move moisture away from the feet is going to help prevent this issue. According to the Clevelend Clinic it helps to reduce friction.

I like to focus on thinner socks for any long run because of the foot swelling, I want to ensure plenty of room remains in the shoe and my feet remain dry.

✅Checkout my best running socks for some ideas >>

✅Also, always use one of these anti-chafing creams >>

Those sticks and creams provide another barrier to prevent friction.

6. Don’t Increase Mileage Too Quickly

Forever and ever I’ll be preaching the mantra of not doing too much too soon.

It’s a major cause of most running injuries.

Your feet, just like your thighs, knees, hips and back need time to adjust to this new pounding.

Many people like to follow the 10% rule to increase running mileage. That’s the process we follow for the majority of our athletes to avoid injury.

7. Improve Your Footstrike

Many times, the problem that leads to a black toenail from running is poor running form and especially in this case how your foot is landing.

If you’re often landing up on the ball of your foot, then you’re pushing the foot farther forward and overworking the calves at the same time.

Learning to land with more of a flat foot under your body is a great start.

✅Get detailed instructions in our Running Form for Beginners Course >>

runner feet

How to Treat a Bruised Black Toenail

While the temptation is HUGE to pull of the nail, that’s a no, no unless advised by a doctor. Instead, we’re looking at a long term process of regrowth.

Step 1: Finding Relief

In the first few days after the Chicago marathon, it hurt when the sheets touched my toe. But I needed to put on shoes to walk around so I found a few things that helped:

Wearing flip flops or going barefoot as much as possible
Covering the toenail with a band-aid or moleskin for extra padding (it hurts to put on but then was a constant pressure that felt better than the random ouch it hit my shoe)
OTC pain relievers to help with the inflammation – not a fan of these prior to running, but helped initially

Once I was ready to run again, I stuck to very thin socks, my roomiest running shoes and avoided a lot of downhill areas sticking to the flats.

Within a few weeks I was largely able to pull on shoes without thinking about it, but still had little flare ups of pain.

Step 2: Allow the Black Toenail Time to Heal

This might be the weirder part of the process. Your bruised or blackened toenail will continue to grow out and overtime be replaced with a nice new toenail.

You might even see a line that looks like a break between the two as the nail plate grows out.

Expect the nail to remain discolored anywhere from a few weeks to a few months depending on how fast your toenails grow. I’m on month six of watching mine slowly grow out. It’s weird.

It might then eventually fall off and you’ll notice a new one growing in its place underneath it.

Why do runners toenails fall off?

Oddly this is not something to worry about. The toenail falling off is common when you have a mild case of runner’s toe.

Usually, after this damage has occurred, the body starts to grow a new toenail.

Eventually, it pushes off the dead toenail…or sometimes the dead toenail comes off before you have that new one.

If this happens and there isn’t any bleeding, apply an antibiotic ointment to the exposed nail bed. This is again why the toe caps can become a good tool (see more below).

runner's toe — A painful example of runner’s toe from TheSoWhatLife

Should You Cut Off a Black Toenail?

NO. You will end pulling off live skin, creating an additional problem and an area now prone to infection from being constantly damp with sweat.

If the bruised toenail is painful and creating a lot of pressure, you can attempt to alleviate it much like a blister.

Sterilize a needle
Try to get the needle just under the toenail where you see a volume of fluid and create a small puncture allowing fluid to release
Apply Neosporin or another anti-bacterial cream
You can try to cover the nail with a Compeed for your toe, they tend to stay on better than a band-aid
Once you are done running and in a clean place, try giving the area time to air out by not using any covering

If the area of pressure is right in the middle of the toenail and not near the edge, the treatment starts to feel a bit more intense. One of the most common recommendations is:

heat a paperclip
place the hot end on the nail and let it melt through the nail
this creates a hole for the fluid to escape
follow the above tips to prevent infection

If you are doing ANY of these during a race please, please follow a few rules:

You have to keep cleaning the area and putting on anti-bacterial so it doesn’t become a bigger issue
Don’t take pain relievers and run – they cause liver damage and have been shown in ultra runners to actually create leg fatigue. Try something like Turmeric pills instead to fight the pain and inflammation.

runner toenail issues

What to Do to Ensure Full Recovery from Bruised Toenail?

Even if you’ve suffered from runner’s toe, it doesn’t need to necessarily set you back much time at all.

Reduce your mileage

Get the right shoes

Protect your toes

Cut back on downhill runs

You’ll be back to training before you know it! Work on your technique till then and follow all the prevention methods listed in this article to reduce the chance of injury in the future.