Why Do Runners Lose Toenails? Plus 3 Preventative Actions

Runners lose toenails

Whether you’re a current or aspiring runner, it's essential to know that losing toenails can be a side effect of high-impact running. But why do runners lose toenails? Read on to find out!

There’s nothing like the gut-wrenching feeling of pulling off your shoes after a long run to find a toenail inside your sock instead of on your toe. It wasn’t until I was in that position myself that I learned runners lose toenails because of trauma to the toe, causing blood to build up and dislodge the nail. Luckily, the situation isn’t as grave as it seems.

Why Do Runners Lose Toenails? The Science Behind The Query

why do runners lose toenails
Running is a high-impact form of exercise.

As a runner, you put your feet through high-impact, repetitive stress. And unfortunately for your toenails, some of that stress comes from them hitting against your running shoes.

No matter how well-fitting your running shoes are (which they should be), it’s impossible to completely prevent your toenails from having run-ins with the front, top, and sides of your shoes.

The result is that blood starts to accumulate beneath the nail plate, a condition that causes your toenails to turn black or deep blue. Black toenails can happen on one or more nails, and it’s rarely a cause for concern as long as it’s not causing you pain.

However, ongoing trauma to your already black toenails via running can cause so much blood to build up beneath the nail that it dislodges from your skin, pushing away until it falls off.

So, what’s the bottom line? 

If you notice one or more of your toenails turning black, you can prevent the nail from falling off by laying off your running until the color turns back to normal. But as a fellow runner, I know this is easier said than done.

The Purpose of Toenails

Whether or not toenails serve a purpose in modern-day life is up for debate. Aside from annoying us long-distance runners, they might help protect blood vessels at the tip of your toe. 

Of course, toenails will be of little help if you drop a heavy object on your foot. But our ancestors likely used their toenails to grasp branches and remove ticks or other external parasites. Scientists also believe that toenails played a crucial role in helping our ancestors dig.

Here’s the good news: You don’t need toenails to run well. So, if you're a runner who lost their toenail, you can expect to have the same performance as before your toenail turned black and fell off.

When to Seek Medical Help

In most cases, black toenails and even toenails that fall off aren’t a cause for concern. However, if you feel pain, you should schedule an appointment with your doctor.

If the discoloration inches its way beyond one-quarter of your nail, it’s also wise to have a doctor check it. In that case, they may end up draining the blood or even removing the nail before it has the chance to dislodge from your toe, which can sometimes be a painful process when it happens on its own.

Preventing Toenail Issues When Running in 3 Steps

Why do runners lose toenails?
Choose suitable running shoes that fit well and leave ample room for your toes.
  1. One of the best ways to present toenail problems is by purchasing running shoes that properly fit your feet. An ample toe box is vital, as it offers toes more space for wiggle room. How you lace up your running shoes can also impact comfort and performance. Check out how to tie your shoes for running and ensure you are getting it right. 
  2. Stick with a regular toenail cutting regime. That way, you won’t have to worry about long nails jutting out into the sides of your shoes, increasing the risk for trauma. The good news is that toenails grow about three times slower than fingernails. So, you won’t have to cut your toenails as frequently. That said, if your toenail falls off from running, it could take as long as 1.5 years for it to grow back fully. Toenails have a growth rate of around 1.62 millimeters per month, so all I can say is follow the age-old advice: a watched pot never boils.
  3. Finally, wearing socks with a cushion in the toe area or purchasing special toe caps are excellent ways to prevent or reduce the impact of runners experiencing toenail loss. 

And remember, your trainers are taking the impact as well, so make sure you know how often to change running shoes.

Regrowing Your Toenail

So why do runners lose toenails? Now you know. But here’s some reassuring news—most toenails regrow. 

Time is the best remedy for runners who lose toenails. That said, it’s helpful to use petroleum jelly on the nail bed as a moisturizer. You can also soak your toes in salt water, which will simultaneously help with healing and kill any bacteria, should there be open wounds on your skin.

As the nail begins to grow, ensuring you keep it protected from further trauma as your run is vital. Otherwise, you could end up at square one with your regrowing toenail falling off.