warmer climates are more likely to suffer because their feet swell in the heat. To prevent black toenails, make sure your running shoes are at least half a size bigger than your normal shoes. Trim your toenails regularly and keep your feet dry for as long as possible during a long run, making sure that you wear proper wicking socks and not cotton ones. Lace your shoes tighter along the front if
you are doing a lot of downhill running to stop the toes from sliding down and
hitting the shoe. If you have a black toenail, the pain should subside after the
first day, and the nail will probably eventually fall off and make way for new
nail growth. If at any point you notice redness or infection, see your doctor,
as antibiotics may be required.