How to Prevent & Treat Black Toenail from Running

Written By: Jeremy N


 Black toenail is one of the most common problems runner’s face when it comes to their feet, and they can happen to runners and race trainers of all types. 

Even if you’ve never had a it before, it is important to know what it is and how to prevent it if you are going to start training for any kind of race. 

Before we dive into detailed tips to help prevent and treat it, let's talk about what it is and the causes for it. 

5 Ways to Treat It Black Toe Nail Safely:

  • Try Toe Spacers. They can help absorb some of the pressure from running
  • Switch Your Running Shoe to One That Fits Properly
  • Trim Your Toenails 
  • Tie Shoe Strings Properly
  • Wear good socks

How to Prevent & Treat Black Toenail from Running

How to Prevent and Treat Black Toenail from Running

What Causes Black Toenail?

The first sign of it is a dark purple, green, or black color that appears under the nail and hurts when pressure is applied. This is a result of bruising under the nail from having too much friction with your running shoes. In most cases you will see it in your big toe before the other toes. 

Unlike a normal bruise, blood blisters that form underneath your nail have no room to swell or “breathe” so they tend to be more painful and take much longer to heal than a normal bruise. 

black toe from running

via the Cleveland Clinic

Many new runners panic and schedule a visit with their doctor. If the problem persists, I would recommend scheduling an appointment.

A quick 15 minute tele-health appointment with a doctor can provide a tremendous amount of additional information and guidance. 

Typically, they last until the nail falls off due to a new nail growing in.

While the biggest contributor is improperly fitted running shoes, they can also appear from wearing the wrong socks (which can also create blisters), doing a lot of downhill running, or from training intensely or for long distances at a time.

How to Prevent Black Toenail From Running?

  • The best way to prevent it is to make sure you have the right fitting shoes. Make sure you select shoes that are ½ to a full size larger than your regular size. There should be about a thumb’s length between your longest toe and the end of the shoe, and you you should have plenty of wiggle room for your toes.
  • Heat and humidity make your feet swell, which allows them to make more contact with the roof and front of your shoes when running. No matter what the climate is, your feet will most likely get hot and sweaty in your shoes when you are working hard, so make sure to wear quality moisture-wicking, temperature regulating socks, and avoid cotton socks.
  • Keep your toenails trimmed and clean. If you can feel your toenail making any contact with the roof or the front of your shoe when you run, that is the first sign of it potentially popping up.
  • Keep your feet moisturized with a good lotion or oil. This is a good way to keep your feet’s skin and nails healthy and less likely to separate from the pressure that’s applied to them from your shoes. Just don’t lather them up before you stick them in your shoes for a run, or else you will create a humid environment that is actually a contributor to the problem.
  • Toe Spacers are a good option that help reduce the impact. Here are the five toe spacers I recommend and the benefits of them
  • If you are running a hilly course, tighten your laces near the front of your shoes, to keep your feet more securely in place as you run up and down the hills. This helpful video shows you how to lace up your shoes to avoid it: 
  • Trim your toe nails. This is a biggie. Longer toe nails are more prone to black toenails
  • Tie your shoes correctly. The video below will help make sure you are doing it correctly. 
  • If you notice that your feet slide around a bit in your shoes, consider getting a rubber or gel insole, which tends to help keep your feet stay in place as you run.
  • As with every other part of your body, your nails benefit from having a healthy diet. Having a diet rich in calcium and biotin will help keep your nails strong and resistant to injury.
  • You can also receive these essential vitamins by taking a supplement, if it becomes a regular problem for you.

How to Treat Black Toenail From Running?

  • Treat it at the very first sign of bruising, and you might be able to save your nail from falling off completely. Treat the bruising with an antibiotic ointment and soak your feet in warm water mixed with peppermint essential oil, or a bath of peppermint tea. The use of peppermint is known to reduce hematoma (black deoxygenated blood) under the nail. Personal preference - I like to use the Majestic Pure Therapeutic Pepermint Oil.  It serves as a great anti-inflammatory and there is not a strong smell like other brands.  
  • If it’s too late to reverse the bruising, then the best way to treat it is to simply leave it alone and let it run the course. Do not force the old nail off or otherwise poke, pull or try to drain the blood. Doing so is painful, unnecessary, likely to cause infection, and will only prolong the healing process. Keep the nail bandaged and treated with antibiotic ointment until it falls of naturally.
  • If you are experiencing a lot of pain, notice redness, swelling or infection - see a doctor. Draining the blood from the nail is an effective way to reduce the pain and swelling, but should be done by a professional in a sterile environment.
  • This might be the toughest of the treatments - Lay off running while the nail is healing, and utilize cross-training workouts. Use a pool workout, a stationary bike, or strength training as substitutes. Don’t worry about losing a week or two of running, cross-training engages different muscle groups and can greatly increase your strength and endurance as a runner. It is recommended to utilize cross-training throughout your entire training process to prevent injuries of all kinds. You can resume running when it is no longer painful to do so, but make sure you keep the damaged nail tightly bandaged and treated with antibacterial ointment.
  • If the nail is partially disconnected from your nail bed, you can gently clip off the dead nail using sterilized clippers. You can also soak your feet in warm water mixed with Epsom salt to help keep it clean and aid in the falling off process.
  • Once the nail falls off, use a topical antifungal to make sure it grows back healthy. The prevents any fungal infection to form. It takes about six months for the nail to grow back completely, and will likely be a little thicker than it was before. While it is growing back, it helps to take a biotin supplement, which is proven to help nails (and hair) grow faster and look healthy. It will take about 4-6 months for the new toe to grow back in. 

7 Tips to Prevent Bruised Toenails from Running

The constant contact that runners' feet have with their shoes means that they are more likely to suffer from bruised toenails. But it can also happen to walkers, hikers, triathletes and cyclists whose foot is pushed into the front of the shoe.

As you take each stride, your foot produces a lot of force against the ground.

1. Larger Toebox in Your Shoes

If a toe box is too tight, it will compress the top of the foot with each step. This often leads to not only issues with the toes, but also problems along the top of the foot.

The Altra Running shoes have been successful for many runners because of their uniquely shaped toebox.

2. Choose the Correct Shoe Sizing

Black toenails can be created by wrong sized shoes.

  • Shoes that are too small will squish your toes, and shoes that are too large will allow for too much movement of your foot. This can lead to issues like blisters. I’ve provided a detailed article on how to tell if your shoe fits properly, but here are some basics:
  • - Being able to place a thumb width 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

If you're considering getting new running shoes because yours seem uncomfortable, try changing the way you lace them first. It might make more of a difference than you think!

3. Extra Downhill Padding

Toe caps or pads are recommended if you'll be running downhill in a race because it will press your foot forward, increasing total pressure.

What are toe caps?

You should avoid adding extra bulk to your shoe or accidentally stepping on other toes, as either of these can create new problems like pain or blisters.

  • The Pro-Tec silicone gel toe cap is recommended by many social media influencers and users, possibly because it's thin.
  • Depending on the shoes you wear or how often you are exercising, decide which toes to put them on (usually just the big toe covers enough area).
  • I personally like to use these with Injini toe socks for additional comfort and stability. Always size up when getting a good fit since they tend to run small.
20 Pieces Gel Toe Cap, Silicone Toe Protector, Toe Guards for Feet, Protect Toe and Provide Relief from Corns, Callus, Blisters, Ingrown Toenails, Toenails Loss - Size Small
  • Silicone gel material: made of soft and durable medical-grade silicone gel material which is non-toxic, odorless and free of latex! Totally environmental-friendly and healthy toe caps!
  • Prevent painful rubbing: toe caps can protect yourself from calluses, blisters and irritation which caused by walking or light activity.
  • Easy to adjust: if toe cap is too long, you can trim down the ends with scissors to fit your toes size.
  • Simple and comfortable to wear: our toe caps are stretchy which can be worn easily. Slim design fits easily in most shoes, boots or sneakers.
  • Large amount: you will receive 20 gel toe caps, and there are enough for you to replace. You needn't worry about damage.

4. Trim Your Toenails

Having short toenails may not be aesthetically pleasing, but they are much healthier for your feet.

Longer toenails can get caught on the front of your shoe and cause pain with every step. Its important to cut them straight across so you don't have any ingrown nails.

You can also go get a pedicure and ask them to make your nails shorter so you can see how it looks yourself for future reference

5. Invest in Good Running Socks

Although it may seem exorbitant, paying $15 or more for a pair of good quality socks is worth it to avoid foot pain down the road. Moisture-wicking and anti-friction properties will help reduce swelling and discomfort during long runs.

Look for thinner sock options to allow plenty of room in your shoes and keep feet dry.

Here are my favorite blister preventing socks

6. Ease Into More Miles

I will never stop preaching the importance of taking things slow at first. Injuries are often caused by doing too much too soon.

Your feet, like the rest of your lower body, need time to get used to the impact of running before you can increase your mileage. The 10% rule is a good way to avoid injury when increasing running mileage.

7. Evaluate & Improve Your Footstrike

Oftentimes, black toenails from running are attributed to incorrect running form. In order land correctly, your foot should be flat with most of the weight falling in the middle. This will take pressure off of the balls of your feet and alleviate strain on the calves.

Last update on 2023-09-25 / Affiliate links / Images from Amazon Product Advertising API

Hi, Jeremy Here, 

I am the the guy behind Train for a 5K. On this site, I share everything that learned along my running journey. The content I create is the running training I wish I had before we started this journeyAbout Jeremy. 

I have run over 250 races including the California International Marathon, Clarksburg Country Run, and various other 5K & 10K races throughout the United States. I am a former Athletics department employee at University of the Pacific and Shoe Consultant with Dicks Sporting Goods

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