Tell Me Tuesday: All About the Black Toenail

The black toenail: newbies fear them, pros welcome them like a badge of courage. While they're not the most aesthetically pleasing bi-product of long-distance running, they're a normal result of upping your miles, and Dr. Douglas Comeau, DO, CAQSM, FAAFP, medical director, sports medicine at Boston Medical Center and the Ryan Center for Sports Medicine at Boston University, answers your most common questions, so you can rest easy (when you're not running, of course).

Yes, we're sparing you the unsightly "black toenail" image, because we all know what they look like. Above: Let's just say there are A LOT of them in this crowd.

What causes them?
Dr. Corneau says there are two causes of a black toenail. The first is a sub hematoma, which is caused by a blow to the toe and bloodflow pools underneath the nail bed. But that's probably not why *you* have the BT. You, my friend, have/will have/have had what's also known as "runner's toe."

Increases in running volume, particularly training for a marathon or other long distance, are the culprit. The reason? "A major increase of a forward motion means more friction and more capillaries will burst," Dr. Corneau explains. "As pressure builds, blood pools underneath the nail bed." Dr. Corneau also cites biomechanical issues as a culprit, such as toes to lifting up against the shoe or gripping too tightly. Frequent downhill running can push the toes against the end of the shoe, too.

How do you prevent them?
Unfortunately, Dr. Corneau says there's no way to 100% eliminate the possibility of black toenails, especially if you're training. Make sure your shoes fit properly, with enough room in the toe box. Major mileage in hot weather will increase the chances of a BT, as your feet tend to swell. But really, this Tribe is tough and driven. We won't let our training and race schedules be driven by the temperature or season!

How do you treat them?
Most black toenails can go untreated. "The nail bed regenerates in about threes months," Dr. Corneau says. A severely damaged BT will fall off once a new, fresh toenail grows underneath, so once the pain wears off, it's simply an aesthetic issue. But if it's extremely painful, you can visit your doctor or podiatrist, who can perform a decompression and drain the liquid underneath the nail bed to relieve the pressure and pain. Dr. Corneau, who admits he has self-drained before (remember: licensed professional), says the worst thing you can do is DIY it at home in a non-sterile environment. Short story: If it's unbearable, head to the doctor.

Can you cover them up?
We've all wondered is a nice coat or two of nail polish can conceal a black toenail without hindering the healing process. Dr. Corneau says paint away. "The nail's already dead; it's not healing," he explains. "You're simply waiting for it to fall off naturally."

But they ain't pretty! Tell us the funniest reaction you've received to a black toenail (your husband, your child, your pedicurist, a complete stranger, etc.) in the comments section on our web site.

12 responses to “Tell Me Tuesday: All About the Black Toenail

  1. My sister got married a few weeks after my first Full Marathon and I suffered a BT. We went in for pedicures and the poor employees face and look of disgust when he saw it. Then trying to explain what happened because I think he was afraid to touch it. I’ve been lucky since, I don’t really get them after wearing a running shoe 1/2 – 1 sizes bigger than I need.

  2. When I was trying on my bridesmaids dress for my brother’s wedding my mother looked down at my feet and said “Why on earth did you only paint one toenail?”. I explained it was from running and I got back “You better do something to cover that up before the wedding!”

  3. Because I started running in the 70s and bought men’s shoes, they were always a little big-especially in the toe box. Which turned out to serve me well in my mountain runs. I still got a few black toenails running down the North Rim of the Grand Canyon…it’s so steep for so long!

  4. my poor pedicurist! now she just shakes her head at me like I am an errant child. but when I first went in, 3 of them had to look over my feet as though perhaps they weren’t sure what was going on. she is gentle with the callouses and blisters, puts unknown ointments on various parts to do various things (she doesn’t speak english very well so I have no clue what she is actually doing), and does a great job of making my toenails (the black and the not black) ones nice and short but still cute for sandals. she mothers all the injured ones along their way and talks to each of them like someone might a houseplant.

  5. I suffered with black toenails for years, and then a shoe fitter told me to buy my running shoes a size bigger than my casual wear shoes. He explained that the pressure in the front of the shoe when running down hills caused the big toe to drive into the top of the shoe frame. Once I increased my shoe size I have now run for decades without any issues. I am old…. so yes decades. Ugh. CH

  6. I haven’t lost a toenail yet (fingers crossed), but I have fewer blisters on my toes now that I lace my running shoes through the “extra” holes on my shoes (you can google ‘what are those extra holes on my running shoes for?’ To see a video). It keeps my shoes tighter around my ankles and my feet don’t push forward as much.

  7. I have also never had black toe nail. I have trained for 2 marathons and a dozen halfs. I love to wear my shoes a half size to big and for several years I have been wearing the Altra’s which have a large toe box. I also treat myself to a pedicure about every 6 weeks to keep my cuticles healthy. Plus my feet look pretty in sandals!

  8. I had a black toe nail once. I didn’t realize it until I took my polish off. Two days later, my wonderful hubby asked to put polish back on it. He was grossed out by it.

  9. I’ve been running for nearly 6 years with 2 marathons under my belt and have never had a black toenail. I consider myself lucky!

  10. The black toenail polish fad was the best thing ever. I still paint my toes dark gray or black to cover the ugly. 🙂 And there are no discounts on pedicures when you have fewer than 10 toenails, either. That’s not fair! The funniest reaction to one of mine in the “almost falling off stage” was my kids calling it my “alien toe.”

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