Black toenails are usually the result of toenail injury. However, there are other things that can cause a black toenail, including fungal or bacterial infections. Most cases of black toenails aren’t ...

If you're a runner, you know that black toenails are common—but that doesn't mean you have to put up with them. Black toenails are common among marathoners and other serious runners, but you don't ...

When Maria Delgado noticed a dark streak under her big toenail, she assumed it was from dropping her gym bag on her foot. Six months later, that seemingly innocent mark led to a diagnosis that saved ...

Tucked inside their favorite pair of running shoes you’ll find what runners consider both a disgusting side effect of the sport and a badge of honor: bruised, black toenails (if the nail is still even ...