As you might guess, there were lots of toe and toenail issues at Western States and Badwater. There were blisters on and between toes, blisters under toenails, toenails floating on top of fluid filler blisters, and toe blisters with blood inside. Some were major and some minor – but to the runner whose feet they were on, they were bad.

Here are two photos I took that shows what is often common at race finish lines. Neither is pretty. The first shows a foot with a large blister under the big toenail. The nail has lifted off the nailbed and there is trauma to the whole area. You can see how the back of the nail is pushed backwards and upwards. The second toe also has a blister. Both have blood inside. The big toenail is thickened.
The second photo shoes a foot with some gnarly toenails. These nails are possibly inflicted with nail fungus, which has gone untreated. You can see the irregular nail surfaces and how thickened some have become. There is some tissue damage but it is hard to tell from the photo if blisters are present. The nail on the second toe may have a blister under it.

These show a common problem that many athletes have not learned – proper toenail care. Thickened nails should be filed down to reduce their height and raised forward edge. Typically, all nails could use some degree of filing to clean up any rough edges. The front edge of all nails should be filed smooth so that when you draw your finger up and over the front of the toe, there is no edge felt.
Any nail rough edge can catch on socks and cause nailbed trauma leading to blister formation. Raised, thickened nails and rough edges lead to problems when the shoe’s toebox is too short or not high enough. Wearing a thick sock, or two socks can add to the bulk inside the shoe and cause pressure on the nails and nailbed. Additionally, socks catching on rough edges of toenails force the nail backwards. Any of these three conditions can lead to toe blisters and blisters under the nail, commonly referred to as “black toenails.”
Care of your toenails should be a regular part of your daily hygiene. Trim them and file them smooth. It a new nail is coming in to replace one lost, file it thin and wrap a Band-Aid around the toe to shape it. New nails often come in irregular in shape and height. While you are at it, use a pumice stone on any toe calluses, especially on the bottom of the baby toe.
If you have toenails that are discolored (with white, yellow, or even brown and black) patches on or under the nail, are thickened, or the nail is crumbling, you may have toenail fungus. The earlier you take care of this, the better. Schedule an appointment with your doctor. Toenail fungus can get worse over time.
If nothing else, before a big race or event, spend some time trimming and filing your toenails to give yourself a better chance of completing the race without problems.