For many runners, thousands of miles of pounding the pavement leads not only to a lean physique and strong legs, but also to unsightly toenails. Toenails that are completely black are not uncommon among runners who tackle high mileage, and although some see them as a nuisance, many shrug them off as a well-deserved mark of their dedication to the sport. Though a lot of runners tend to ignore them and run through the pain, black toenails do pose some health risks. Therefore, it's worth your while to prevent and treat them, whether you see them as a curse or a sign of toughness.

Risks Associated with Black Toenails

The main worry associated with black toenails is that they might become infected. When your toenail turns black after a lot or running, it is because the tissue underlying the nail has been damage. A black toenail is essentially a blood blister than has formed under the nail – the black color develops as the blood sits and darkens. Like any wound, the wound bleeding underneath your nail can become infected, and its location makes it hard to treat. An infection that starts beneath your nail bed could spread through your body, even landing you in the hospital.

Treating Black Toenails

If you notice a black toenail developing, take care to keep your foot clean to reduce your risk of infection. Use peroxide or iodine solution to clean the nail and surrounding area several times per day. Usually, a black toenail will fall off within a few weeks. When this happens, resist the urge to pick at the nail, as you may contaminate the area. Apply an antibiotic cream to the nail bed for several days, and let the new nail grow in naturally. Wear loose shoes until the nail heals.

If the area around your black toenail is swollen or more than slightly sore, it's a good idea to see a podiatrist. He or she will determine whether the toe is infected and may need to remove the nail in order to treat the infection.

Preventing Black Toenails

If your toes are in good shape now, wearing the proper running shoes will help keep them that way. For most runners, wearing shoes that are ½ size larger than their street shoe size helps give the toes more room to move, reducing the chances of black toenails. Wearing moisture-wicking socks, especially when it's particularly warm or wet outside, also helps protect the toes. Keep downhill running to a minimum, as this puts increased pressure on the toes.

While showing off your black toenail may convince your friends you're dedicated to your sport, you'll have a hard time running on an infected, painful toe. Avoid black nails when possible, and have them treated by a podiatrist in your area at the first sign of infection.