Some say it’s a badge of honor for any runner. Others shudder in disgust. Whichever camp you fall in, if you’ve ever had a toenail falling off running, you’ve experienced the unfortunate situation referred to as runner’s toenail.
A survey of 719 trail runners found that toenail injuries were actually the most commonly reported injuries amongst the runners, with 24.8% (nearly 1 in 4!) of the runners noting runner’s toenail, a toenail falling off from running or other toenail injuries in the past 12 months.
In this guide, we will discuss runner’s toenail and ways to stop a toenail falling off from running.
We will cover:
- What Is Runner’s Toenail?
- What Causes Runner’s Toenail?
- How Does Running Cause Toenails To Fall Off?
- Other Causes Of Runners’ Toenails Falling Off
- Does It Hurt If Your Toenails Fall Off After Running?
- Problems Associated With Toenails Falling Off From Running
- 6 Ways To Stop A Toenail Falling Off From Running
Let’s get started!
What Is Runner’s Toenail?
Runner’s toenail, which is the common term for the medical condition called subungual hematoma, refers to a condition where your toenail becomes black or bruised from running.
Whether your toenail looks black, blue, or purple, the discoloration associated with runner’s toe is due to blood trapped under the nail that has leaked out from broken blood vessels.
A “hematoma” is a bruise, so runner’s toenail, or subungual (under the toenail) hematoma, is essentially a bruised toenail.
Oftentimes, the bruised toenail from running will eventually fall off, which is why toenails falling off from running is quite a common malady amongst distance runners.
What Causes Runner’s Toenail?
Runner’s toenail is primarily caused by repeated stress on your toenails as you run.
Rather than resulting from one acute misstep while you run, runner’s toenail or toenails falling off after running is typically because of the accumulated microtraumas your toe experiences during the gait cycle.
In other words, black toenails in runners are more likely to result from the toenail repeatedly ramming into the front of the shoe while running rather than from the runner accidentally taking a swift kick to a big rock or tripping on a curb.
The most common toenails to fall off running or after running are the big toenail and the second toe’s toenail.
This is because they are usually the longest toes; therefore, these toenails are most likely to take the brunt of the force or trauma inflicted on the toenail during the running stride.
How Does Running Cause Toenails to Fall Off?
So, how exactly do toenails fall off because of running?
Let’s look at what happens with runner’s toenail:
When you run, your toenails can be subjected to repetitive micro-traumas that, together, sum to cause noticeable damage.
Essentially, there are two phases in the running stride that can inflict itty-bitty damage to your toenails.
The first occurrence is at the initial impact of each foot with the ground. This ground contact phase results in a brief moment where your foot is still moving forward in your shoe, but your shoe itself is planted and not moving.
As your foot slides forward in your running shoe, the toenails may ram into the inside end of the shoe.
The second occurrence in the gait cycle where your toenails may take on excessive stress is when you push off—referred to as the toe-off phase—to propel the next stride forward.
During this motion, your toenails may ram into the footbed of your shoe as they dig into it when you press into the ground.
Because you take thousands of strides per run, the stress of these injuries, although seemingly tiny, accumulates and can damage the blood vessels under the toenail and supply the nutrients the nails need to survive.
Not only does this result in a visible bruise or black toenail, but it can also cause a runner’s toenail to fall off because, without an adequate blood supply, the toenail will die.
Other Causes of Runners’ Toenails Falling Off
Runner’s toenail is the primary reason why runners’ toenails fall off, but there are a few other potential reasons why your toenails might fall off.
Some runners get blood blisters under their toenails, which can eventually cause the toenail to fall off.
Blood blisters under toenails usually result from repetitive friction over damp or sensitive skin.
For example, your toenail might be shearing back and forth against the top surface of the inside of your running shoe as you run.
Although toenails falling off from running are usually due to bruised toenails from runner’s toenail, there are a few other potential causes of bruising and bleeding under the toenail in runners, such as:
- Fungal infection
- Heart or kidney disease
It is advisable to consult your healthcare provider if you have concerns about any of the above conditions.
Does It Hurt If Your Toenails Fall Off After Running?
Generally speaking, if you lose a toenail after running due to runner’s toenail, it will be relatively painless.
The toenail falls off because it has died, so it should be less sensitive already.
However, before the nail falls off, a black toenail from running may feel tender or more sensitive if it does bump up against the inside of your shoe.
The most common signs and symptoms of runner’s toenail include a darkening of the toenail (usually the first or second toe), pain and tenderness, pressure under the toenail, a loosening of the nail from the nail bed, and the toenail falling off from running.
Problems Associated With Toenails Falling Off From Running
Aside from causing discomfort, toenails falling off from running can leave your nail bed vulnerable to injury.
The nail bed has very delicate and sensitive skin, which is why the toenail is normally there to protect the tissue.
If your toenail falls off from running, you might want to cover the nail bed in a light, protective dressing such as a sterile Band-Aid or gauze.
Depending on the condition of the nail bed, remaining toenail fragments, and blood vessels, it is also possible for the area to become infected. Signs of an infected toenail include redness, swelling, more intense pain, warmth, and drainage or pus.
To prevent infection after your toenail falls off, soak the affected foot in warm salt water several times per day and wear clean, dry socks.
6 Ways to Stop a Toenail Falling Off from Running
Runners don’t need to lose a toenail to show that they are gritty and hardcore. Preventing runner’s toenail will save you from cringing at the unsightliness of your toes and the associated discomfort of losing a toenail from running.
Here are the top ways to stop a toenail falling off from running:
#1: Trim Your Toenails
Regularly trimming your nails so that they stay neat and short can prevent them from jutting out beyond your toe.
When your toenails are too long, they extend beyond your toe, leaving them in a vulnerable position to collide with the inside of the shoe.
To minimize the risk of ingrown nails, clip your toenails straight across rather than in a curve.
#2: Wear Running Shoes That Fit
When it comes to getting the proper fit with running shoes, most people focus solely on the size of the shoe, but it’s also important that the shape and width of the shoe adequately fit your foot.
Different running shoes have slightly different shapes, especially in the toe box.
The running shoe should have about a thumbnail’s width between the end of your toes and the shoe in terms of length.
In terms of width and volume, you should be able to freely wiggle your toes without them bumping into the sides or top of the shoe. The shape of the toe box should mimic the same of your toes. For example, some running shoes have a more tapered toe box that comes to a point, whereas others are more squared off and broad.
If the shoe is squishing your toes together, your toenails are more apt to run against the sides or front of the shoe, which can cause bruised toenails.
#3: Use Your Laces
Shoelaces are there for a reason: they allow you to tighten your shoe and customize the fit.
Runner’s toenail can occur from excessive sliding of your foot inside the running shoe.
Lace your shoes tight enough to hold your foot in place.
There are different running shoe lacing patterns that you can use, and it’s usually helpful to play around with each to see what works best for you.
#4: Wear Running Socks
Runners focus a lot on their running shoes in terms of preventing toenails from falling off running, but your socks matter, too.
Cushioned running socks with a seamless toe can help absorb force and shield your toenails from ramming into the end of the shoe.
With that said, it’s important to ensure your running shoes still fit properly with a thicker, more cushioned sock. You should ideally bring the running socks you want to wear with you when you are fitted for running shoes, or speak to the specialist to get the right socks while you are there.
Running socks should be moisture-wicking.
#5: Watch Your Terrain
Excessive downhill running can cause your toenails to take a beating, hitting the inside of your shoe.
#6: Use Moleskin or Silicone Pads
If your shoes fit well and your toenails are trimmed, but you’re still having toenails fall off from running, you can place adhesive moleskin or silicone pads at the ends of your toes to act as shock-absorbing bumpers inside the running shoe.
We want to prevent runner’s toenail and any other impediment that can hold up our running.
Take preventative care of your feet to try and avoid any and all issues that could come up. For more tips on how to care for your feet, check out our preventative care guide for distance runners.