Real human data. Wrong route.
GHK-Cu has actual clinical evidence behind it. Most peptides in this niche don't. But "evidence exists" and "evidence applies to how you're using it" are two different claims — and this compound is the clearest example of why that gap matters.
What it is
GHK-Cu — glycyl-L-histidyl-L-lysine bound to copper — occurs naturally in human plasma and declines with age. It has real, published human trials. All of them tested topical application on skin.
The mechanism
Copper-peptide complexes like GHK-Cu are studied for their role in modulating collagen synthesis, tissue-remodeling gene expression, and antioxidant enzyme activity at the skin level — the basis for the cosmeceutical research that exists on this compound.
The evidence, by route
Tier B Topical — small-to-moderate human studies on skin appearance, collagen markers, and wound healing exist and are published. This is genuinely one of the better-supported peptides in the category, within that context.
Tier C Injectable — no comparable human trial evidence. What exists there is preclinical.
The framework
Before accepting "human data exists" as evidence for a use case, ask: data exists for which route, which dose form, which population? Evidence doesn't transfer across routes just because the molecule is identical. This is the single most common evidence-bridging error in the category — citing a real study while quietly changing the route it was studied in.
Looking for a specific product or batch?