I've used it.
Works but if you are having pain you need to think about a few things:
1) Why are you having pain?
2) Is masking the pain really worth it right now?
3) Do you really like the smell of soured milk?
I've taken things for pain before. 6 days before my last contest (big one) I tore something in my right foot. It still isn't right but MUCH better. I did all I could to try and compete on contest day...including taking lots of local and intramuscular injecions of pain meds and killers (ones that would not hurt my mood or performance). Had to...it was for TV, money, and of course for the love of the sport and representation of my USA Country and Flag.
When it was all said in done...I did 1 event and was hurt so badly that I couldn't even get my shoe off. My foot didn't even look like I foot at that point either.
Regret it? Nope...I just wonder how much of that injection that I should have taken to kept the swelling down and the pain away till the contest was over.
B True