Top 5 Mistakes Runners Make with Their Toenails

Top 5 Mistakes Runners Make with Their Toenails

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Top 5 Mistakes Runners Make with Their Toenails

Which is better…clear healthy toenails or thick, yellow, black and blue or missing toenails? Running can be hard on the feet. We all know that lots of runners bash their toes. But neglected tootsies can lead to discolored toenails and even lost toenails if you’re not careful.

I’m Dr. Christopher Segler and I am a sports medicine triathlete who treats runners and triathletes and here are the top 5 mistakes I see runners make that can lead to funky looking toenails.

1. Wearing shoes that are the wrong size.

Without a doubt the most common complaint I hear from runners about toenails is that they often get bruised after long runs and marathons. The bruising under the toenail is just a sign of trauma. You can hit the toenail once with a hammer or 10,000 times on the inside of a running shoe yet the cumulative force applied to the toenail can be about the same.

The result is a black or blue toenail. That is basically a bruise or blood blister under the toenail. Repeatedly beating up your toes in this way leads to several common problems:

  • Toenail Soreness. The toenail can become sore because a blood blister is causing pressure underneath the toenail. In some cases when this happens a doctor has to drain the blood from underneath the nail to relieve the pressure.
  • Lost Toenail. The toenail can actually fall off because the blood blister is so extensive that it lifts the nail plate right off of the nail bed. This can put you at risk of a variety of different infections including fungal infections and bacterial infections.
  • Permanent Thickening. As the root of the nail getting smashed (which leads to a bruise under the toenail) the root of the nail or “toenail matrix” can get so smashed it deforms and becomes misshapen. The problem here is that when the root of the nail (which doctors call the “matrix”) becomes deformed the toenail then grows out in the same shape as the smashed thickened matrix. Then the toenail grows out thicker. It may be greyish, or yellow in color and often looks like a fungal toenail, but it may not have any fungal infection in the nail. Toenail fungal infections are treatable and curable, but permanent thickening because of repeated trauma to the toenail is permanent ugliness.

If you’re running in shoes that are the wrong size for you, the toe may be tapping the toe on the inside of the shoe repeatedly. Although it may not hurt at the time it can result in the cumulative trauma the can lead to all of the different problems that we just mentioned.

What most patients find hard to understand is that the same problem can happen when their running shoes are either too small or too big.

Most runners understand that if their shoes are too tight the toes are going to be compressed on the inside of the shoe. So if they get shoes that are too tight often times they’ll just go up a half a size or a full-size when buying their next pair of running shoes.

The problem with this strategy is that if the shoes are too big, the foot can slide forward when running downhill and impact the inside of the toe box. The end result is trauma to the toes and funky looking toenails.

2. Improper trimming of toenails.

The length of your toenails can have a huge impact on the amount of friction and irritation to the toenails themselves. If your toenails are even a little bit too long it’s much easier for them to scrape the inside of the running shoe when you’re running uphill or downhill.

So, in general, when runners keep the toenails trimmed short, the toenails are much less likely to hit the inside of the shoes and sustain the kind of trauma that can lead to bruising, soreness or damage to the toenails.

If you think about the amount of friction that occurs when the nails actually hit the inside of the shoe you can understand that actually smoothing down the edge of the toenail can help a lot. It only takes a few minutes and it’s worth the effort to file the edges of the toenails whenever you cut your toenails. Freshly cut toenails have sharp edges. Those sharp edges are more likely to catch on your shoes and your socks. And again, too much friction can lead to trouble.

But a word of caution. Don’t go crazy trying to cut the toenails as short as you can. The goal is to make sure that the toenails not going to impact the inside of the shoe. But if you trim the toenails too short you can put yourself at risk of ingrown toenails. I get calls from runners all the time who have ingrown toenails that are not only painful, but in some cases can lead to infections that require antibiotics and even minor surgery. So trim those nails with care!

3. Not using skin lubricant on long runs.

Whenever a patient calls me after they have done a marathon and they complain of sore toenails, my first recommendation is to check the shoes. Provided that they have been running in those shoes and haven’t had other issues on shorter runs then it is likely safe to continue using those same shoes and just add a skin lubricant to decrease friction to the toenails.

On a personal note I can tell you that when I do marathons and Ironman triathlons if I put body glide on my second toenails I have no pain and no issues at all. Yet if I don’t put body glide on my second toenails then I will most often have soreness in the toenails, visible bruising in the toenails or even lost toenails after those races. I have experimented and this is consistently true for me.

I am quite certain that I’m using the right shoes. And I also know that I can run up to 20 miles without developing enough trauma to cause any pain or damage to my toenails. But when I run longer I am at risk. The skin lubricant applied my second toenails decreases the friction and irritation just enough that I don’t get any cumulative trauma that could lead to toenail damage.

4. Forgetting to dry shoes.

Anytime you run your feet are going to sweat. Even if you run in a dry climate like California or Arizona, your feet are going to be damp. The result is that the inside of your shoes are going to be wet. Moisture in your shoes will create the perfect environment for fungus. The fungus that thrives in shoes can lead to athlete’s foot and/or toenail fungus infections.

To get a toenail fungus infection you have to have the live fungus or fungal spores present. And the fungus has to have some way to get into the toenails. Trauma is the way that the spores and fungus get into the toenail. So we already talked about how trauma can lead to damage of the toenails. If you have that trauma (as in the toes tap on the inside of the shoe) and you happen to have fungus on the inside of your shoes, those little bugs can get in there and start trouble.

Toenail fungus is notoriously difficult to treat. But it’s really easy to prevent it. The best way to prevent toenail fungus is to keep the moisture out of your shoes.

All you have to do is leave your running shoes in the sunlight or near a heating or cooling vent in your home after you go running. If you want to be especially thorough you can even remove the inserts from the shoes to make sure they will dry completely.

The next time you go for run take off your running shoes and pull the insert out of your shoes. Then look at the bottom of the insert in the inside of the running shoe and see just how much moisture has accumulated in the foot bed. I think you’ll be surprised by how damp the shoe is.

The very worst thing that you can do is run at the gym and then toss your running shoes inside a gym bag, zip it up and toss it in the trunk of your car or your closet. If you’re damp post-run running shoes are left enclosed in a gym bag they will stay moist and create the perfect opportunity for fungus to thrive.

Take time to dry your shoes after you run and you will dramatically reduce your risk of fungal infections that can lead to nasty thick, yellow toenails.

5. Not treating toenail fungus as soon as it starts.

Toenail fungus is extremely common. It is also progressive. Toenail fungus virtually never goes away on its own. And although it doesn’t usually get worse very quickly it will get worse over time. The longer you have the toenail fungus infection the thicker the nail will become. That of course makes it even more likely that the nail will continue to impact to the inside of the shoe when you run. Overtime this can lead to chronic pain in the toenails.

And yes, fungal toenails are ugly! They are thick, yellow and they’re just plain gross. The main reason that people call me asking to treat their toenail fungus is not because of pain, but because the toenails themselves just look disgusting. You don’t have to be embarrassed by your toes! Don’t let it get to the point that you don’t even want to go barefoot or wear flip-flops. Don’t let it get to the point that you’re afraid to show off your toes. Toenail fungus can be really embarrassing but it is certainly treatable.

The fact of the matter is that the toenail fungus will damage the toenail. And as the toenail fungus filaments bore through the toenail and separate the layers of keratin, the nail gets thicker and thicker. Over time, the damage just continues to spread.

It’s much easier and much faster to treat toenail fungus right when it begins. If you have notice any yellow or white areas of discoloration, find a toenail expert and make sure that you treat it as quickly as possible. Don’t wait until the entire nail becomes infected. It’ll just take longer to fix it.

Just because you love running you don’t have to live with discolored thick toenails. All you have to do is figure out what is causing the damage to your toenails and stop doing it!

But you don’t have to stop running. You just have to make sure that you’re wearing shoes that the right size, keeping your toenails smooth and an appropriate length. When necessary use a skin lubricant to decrease the irritation to the toenails. And if you have any suspicion that you might have developed a fungal infection that is causing damage and discoloration to the toenails you should certainly get it checked out by a podiatrist so you can start getting back on track to clear healthy toenails right away.

If you have a question that you would like answered as a future addition of the Doc On The Run Podcast, send it to me And then make sure you join me for the next edition of the Doc On The Run Podcast.