The Fix

How to Deal with Black Toenails

I’ve had more black toenails than I can count,” says Krista DuChene, the Brantford, Ont.-based marathoner who finished third in the 2018 Boston Marathon. “I’ve accepted the fact that I would not be a foot model.” If you’ve experienced a black toenail or even a few, you’re in good company.

Black toenails (also sometimes referred to as runner’s toe) are caused by a subungual hematoma – a bruise or blood blister under the toenail. The good news is they are not harmful. They’re also treatable, and in many cases, preventable.

The first step is understanding why it happened. Marathoner and 2015 Pan Am bronze medallist Rachel Hannah shares her experience:

“When I started increasing my mileage and running marathons, I started to get some black toenails. Thinking back to what caused them, it was actually shoes that were too tight, not the running itself. Fortunately, I am sponsored by New Balance, and they make different widths in shoes, so I switched to a D width and that solved the issue. I also go a half size up in some models.”

Hannah also works with Jim Marando, a chiropodist at the Niagara Foot Care Clinic in Grimsby, Ont., who has treated many runners with this injury. “Jim has made me custom, running-specific orthotics over the years and has helped with manual adjustments to my feet to keep me running healthy,” she says.

Marando is quick to point out that there may be other contributing factors besides how your shoes fit: “Body alignment and imbalances, foot mechanics, foot shape, or even having a toe that is longer than the next, like a Morton’s toe (in which the second toe is longer than the big toe) are all part of the mix,” he says. “Often these bruised toenails are correlated to f lat feet and loss of the metatarsal arch, toenail fungus or toes retracting and the top of the toenail going down into the shoe.” He says that all of these conditions can lead to black toenails, which, in themselves, are not harmful.

Although the importance of proper footwear and fit cannot be overstated, pro triathlete and pedorthist Ryan Grant of SoleFit in Vancouver suggests another way to prevent black toenails is to increase your distance gradually, so that your toes get used to the added pressure of longer mileage. “Remember, every time you take a step, your toes get an injection of blood, and in warmer conditions, your feet swell, adding to the internal shoe pressure,” Grant points out. If you’re training for marathons or ultramarathons and putting in long mileage, sometimes black toenails are unavoidable, simply due to the repeated trauma over time.

Should you pop the blood blister to relieve pressure? “It’s always recommended to seek the advice of a medical practitioner to have it properly diagnosed, especially if you’re experiencing any pain,” says Dr. Michael Clarfield, a sports medicine physician at the Cleveland Clinic in Toronto.

Ill-f itt ing shoes can be eit her too big or too small, so, t ake your time and try on a few styles. As a marathon runner, Hannah puts in up to 160 kilometres a week, and she is still affected by runner’s toe. So, it doesn’t matter how experienced you are and how well your shoes may be f itting at the time – black toenails are about repeated trauma over time. Find your cause, and you’ ll f ind t he solut ion.

Marylene Vestergom is a regular contributor to Canadian Running. She’s covered sports, including multiple Olympic Games, for over 20 years.