What to Do If Your Toenails Turn Black From Running
If your legs hurt on short runs, you are probably just wearing the wrong shoes. But toenail problems often occur when you start increasing your mileage, for example when preparing for a marathon. Here’s what to do if you have black toenails or worse.
(What could be worse than black toenails? Turns out toenails can fall out if they are traumatized enough. If this has never happened to you, you are probably completely disgusted now. If it happened – and I was there – you know it’s not really that important and they grow back. But more on that in a second.)
Why do my toenails turn black?
Typically, a black (or blue or purple) toenail is just a bruise that you can see because you have a clean toenail. We will talk about this today. These bruises can appear suddenly – for example, if you drop a dumbbell on your toe – or they can occur when you bump your toes in front of your boots thousands of times every mile.
There are other reasons why toenails can change color, some of which are described in this World of Runners article . These include normal pigmentation changes that can occur over time, various types of toenail fungus, and even some types of skin cancer. For example, discoloration that extends beyond the nail is cause for concern; so is the black spot that stays in place for months and does not grow or disappear. But usually, if you increase your mileage and your toes start to blacken, the reason is obvious.
Choose your shoes
Toenail bruises are common among people who run a lot, but are by no means inevitable. If you have bruises on your feet all the time, it is likely that your shoes are too tight in the toes.
My first black toenails came when I started training for a marathon after years of never running more than three to five miles in a row. I bought a size 8 trainer to fit my 8 foot size and have been fine all these years. But when it came time to buy a new pair, I switched to 8.5. My toenails stopped blackening, and as a bonus, my blisters stopped appearing.
Your feet swell a little as you run, so it’s wise to buy shoes that keep this in mind. (As long as you keep the laces tight against the instep, the shoe won’t slip.) You may not need the extra space on short runs, but when you’re hitting serious mileage, that half size makes a big difference.
Change socks
If you are running in thick socks, switching to thinner ones will save space. As a bonus, thin socks made specifically for running often make your feet less prone to blistering.
Cut your nails
Another way to keep your nails from getting into the front of the shoe is to trim them. Cut them as short as you like ( too short can also be irritating), and trim or file them often to stay that way.
Color them maybe
In the summer I had all those black toenails and started buying nail polishes in interesting colors. The bruises will show through anything, but it was fun experimenting with dark colors, including blues and purples.
I could not find a consensus of experts on whether it is bad to paint bruises on the legs. It is not true that nails have to “breathe” (toned tissues get oxygen from our blood, not directly from the air), but in some cases the nail polish and chemicals we use to remove it can help dry the nails out, or they can simply make it difficult to check if the nail underneath is healthy.
I will say that many runners paint their nails without any side effects, but if you have any doubts, you can save the nail polish for special occasions as well. The dark color of the bruise will grow over time.
Get help if they are injured
The accumulated blood under a bruised toenail can cause pressure so hard that it hurts. A doctor or other healthcare provider may pierce the nail to drain fluid and relieve pressure.
There is no shortage of instructions on the internet for how to do this yourself, using a hot needle, paper clip, or even a drill. Although people have done this, we do not recommend self-surgery. Either way, toenail drainage is necessary when the pressure of the fluid under the nail is causing pain. It won’t do anything with toenails that are painless or mildly painful after being blackened from a slight bruise.
Looking forward to when they fall
This is the fun and rough part; sometimes injured toenails fall off. Sometimes they turn black and then fall off, but they can also fall off without obvious bruising, or vice versa.
This is less harsh than it sounds, because the new nail begins to grow under the old one. You may not even notice what is happening until the new nail is mostly in place. One day, you’ll just trim your nails and notice that one of them comes up easily – it’s the older, upper nail that is getting ready to go out.
This transition period can be awkward and you have two options. First, if the nail is still mostly stuck, cover the nail with tape or sports tape, making sure the loose edges do not snag on the toe or inside of the shoe. Since the fresh new nail underneath is thin and may not yet cover the entire nail bed, leaving the old nail will help protect your toe.
Another option is to remove the old nail, which you can do as soon as you feel it is better than sticking it on. Consider using a nail trimmer to get the job done neatly (instead of being blunt and hoping for the best), then use a file to smooth out any irregularities.