Had the same issue — I'd heard people talking about injecting BPC/TB-500 directly into the problem area or even "in the knee," so I tried the back of my thigh and still got a little itchy spot. Switched to the belly and it was totally fine. Since I'm new to this I was also wondering what injecting "in the knee" actually means in practice, though I did read that since peptides are systemic it doesn't really matter where you inject and fatty areas like the belly work just as well.