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 ...

Toenail fungus, or onychomycosis, is a nail infection that can make your toenails thicker, change color, or break apart. It affects about one in 10 people and is common in adults over 60. While fungi ...