Couch to 5K
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What will happen to my black toenail

My big toenail has gone black and is mega painful!

I thinks its from the Edinburgh 10k, it was really hilly and there was some steep downhill bits and my toes were sore after.

Has anyone had experience of this?? Do i need to do anything or will it just fix itself. I'm hoping it doesn't fall off, I don't like the idea of that at all!

4 Replies

Yeah I had this when I climbed Kilimanjaro, when I was going downhill - it's just from your shoes pressing on your toes.

No need to do anything unless they look like they're getting infected or something, just leave them to it and, as gross as it sounds, it will drop off eventually. When it does, it may leave your toe nail-less for a while which is a bit painful, but just plaster it up :)

Congrats on the 10k, and the hills! I'm struggling to run less than 5k on a slight incline at the moment, so it's good to have something to aspire to!


Just keep dabbing on TCP for any infection and Arnica cream for any bruising and it should take care of itself. Sometimes the nail will just come off, or a new one will grow upwards or underneath and push the old one off.

I would just focus on your fantastic achievement! WOW!


What saffron said - I had both my big toenails go black after loosening (stupidly) my walking boots to come down Snowdon last September. One didn't fall off and half of one did after a few months. Basically watch out for them but it isn't a great problem. If they get loose tape over them.


Well my toe nail went black last year, but not from running, I wore heels that were to high to a wedding and 12+ hours in those shoes left me with two painful and black toe nails. Reading this now, it must have been from my foot sliding forward slightly, rather than running/walking downhill.

My right toe was quite dark, the left a more of a light grey that cleared quite quickly. I didn't loose either toe nail, didn't take a break from running or do anything special because my running shoes were a good fit around my toes and didn't cause any discomfort.

The pain if I recall only lasted a short while, but it seemed like I was left with a black toe nail for a good couple of months at least, which was not a great look in the summer and I was afraid to put nail varnish on as I wanted to monitor it :)


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