I've also seen a lot of talk about GHK-Cu lately, especially for hair and scalp. The interesting thing is that there's a plausible biological basis, but when you look at human studies on hair regrowth, the data is still quite limited.
I work with
Peptides.io , and we've compiled what's really known about GHK-Cu, including its effects on hair, here:
https://peptides.io/peptides/ghk-cu/
Personally, I'd see it more as a complement than a replacement for treatments with more solid evidence. Has anyone here been using it for at least 3–6 months and noticed any real differences in density or hair loss?