Dear Running Doc:
I am a 26-year-old runner and in my career of running I have had multiple black toenails which have fallen off. Fortunately, it’s my toe which gets covered by a shoe or nail polish. Maybe I am just prone to black nails. Recently I pinched my pinky finger nail. I don’t want it to turn black and fall off. Will that happen?
Andrea L., San Francisco, CA
Thanks Andrea for the excellent question. There are no articles I’ve read that find that people are prone to black nails. Perhaps we need a better understanding.
Bleeding that occurs under a toenail is from repetitive trauma where that toe hit the end of your shoe. If the toenail has leaked to relieve the pressure that can cause pain, so much the better. If it hasn’t and the condition is painful, a doctor can put a hole in the nail to relieve the pressure. In any case, the black color is just the blood under the nail drying up. It will be reabsorbed. The nail may die and fall off; no worries, a new nail will grow in behind it.
To prevent black toenails, follow these guidelines:
1. Make sure your running shoes fit properly. Buy them at the end of the day when your feet are the most swollen. Make sure there is a thumbnail’s distance between your longest toe (which may be your second toe) and the end of the shoe.
2. Make sure your toenails are trimmed before you run. Sometimes an extra long nail can hit the front of the shoe and cause bleeding beneath the nail.
3. Make sure your insole or orthotic is not slippery. Sometimes slippery insoles make the foot slide forward and the toe hits the front. Try putting a nonslippery covering over your insole or orthotic; something like those Dr. Scholl’s foam pads (white with little holes in them) you can find in almost all drugstores will work for this purpose.
Fingers and toes are very different. No repetitive injury with your hands is possible. Fingernail injuries can be traumatic and black nails formed with blood under the fingernail are commonly seen in high impact pinching like getting caught in a car door.
Andrea, it is hard to tell you if what happens to your toe will happen to your finger. Fingers are much rarer than toes. If it bleeds beneath the nail make sure there is a small hole to drain the blood. Soak the finger daily in warm water to help prevent losing the whole nail.
I hope this helps. If you have any further questions do not hesitate to write.
Enjoy the Ride!
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Lewis G. Maharam, MD, FACSM is one of the world’s most extensively credentialed and well-known sports health experts. Better known as Running Doc™, Maharam is author of Running Doc’s Guide to Healthy Running and past medical director of the NYC Marathon and Rock ‘n’ Roll Marathon series. He is Medical Director of the Leukemia & Lymphoma Society’s Team in Training program. He is also past president of the New York Chapter of the American College of Sports Medicine. Learn more at runningdoc.com.
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