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How To Prevent Black Toenails (Or Hide Them With Nail Polish)

A bruised toe nail, otherwise known as a black toenail, can be a problem for runners of all distances.

The typical cause of a black toenail are running shoes that are too small. However unfortunately they can also happen during long distance events such as the marathon, when there is a repeated force on your toes for an extended period of time.

To prevent this from occurring you want to make sure you are purchasing the correct size running shoe. Your running shoes are going to be larger than your regular shoes. So if you are say an 8, you will likely be an 8.5 or a 9, depending on the brand, how large your feet typically swell during exercise, or even the time of year it is.

Claire Wood, Sr. Footwear Product Manager, Global Running, at New Balance explains it like this:

Bruised toe nails, and even toenail loss, is most often due to too much pressure on the front of our shoes as we run. While the shoes may not feel too small at try on and actually may feel perfect, the extra room, often a “thumbs nail length”, is recommended to accommodate slight foot swelling or even simply what we refer to as “toe splay”. With each step, we push off of our forefoot, and our toes spread, or “splay” as we say. This is why we engineer a forefoot area, that has mesh or overlay placement to accommodate this. At New Balance we hyper-focus on heel fit so that the collar area and materials hold the heel in snugly, as well as a nice midfoot wrap around the arch area. The key fit in these other areas are truly all working to allow the forefoot the important freedom it needs.  If our foot is even a little too close to the edge of the shoe, mile after mile, this will only become tighter, resulting in some toe nail damage. Worse than toe nail damage, if your shoes are way too small, you could risk injury to other areas due to compensation.

It’s always wise to make sure one of the biggest shoe sizes in your house is your running shoes. I assure you that half size up will make your feet much happier and your pedicures more enjoyable.

Now that we know how to prevent this from happening here are some color tips and nail polish colors to cover up your black toenail in the meantime!

Tips for picking a color:

  • Stay away from reds, they will end up looking purple on the offending toe
  • Stay away from light colors
  • Spice up black by using a top coat with glitter
  • Deep purples, dark grey, and black work best

Here are six nail polish colors that are great for hiding that black toenail until it returns back to normal!

Opi Lincoln Park After Dark

Opi Vant To Bite My Neck

Opi Black Cherry Chutney

Opi Eiffel For This Color

Essie For The Twill Of It

Essie Licorice

Read More About Foot Care:
The Foot Treatment An Ultrarunner Says Is Crucial
4 Products For Happy Runner Feet


Mile Posts

Mile Posts

Dorothy Beal is the creator of the #irunthisbody and #IHaveARunnersBody MOVEments and the owner of, a website that sells fun running tees and jewelry! She is a mother of three who started running in college as a way to lose weight literally and figuratively and got hooked in the process. In 2003 she completed her first marathon and has run 31 of them since. Sharing her passion for running is one of the things she most enjoys behind being a mom. You can find her writing about life as a runner on her personal blog at and follow her on Instagram, where she shares her life in photos @mileposts.