Ingredient or product comparison
Absence of head-to-head human comparison
There is no published human study that directly compares injectable GHK-Cu against topical GHK-Cu for any skin endpoint. The comparison in this article is therefore assembled from separate bodies of evidence — human topical cosmetic studies on one side, animal
This source-based comparison does not add ratings or recommend a winner.
- There is no published human study that directly compares injectable GHK-Cu against topical GHK-Cu for any skin endpoint. The comparison in this article is therefore assembled from separate bodies of evidence — human topical cosmetic studies on one side, animal and mechanistic work on the other — rather than from a single trial that pits the routes against each other. Cross-body-of-evidence comparisons are inherently weaker than a controlled head-to-head, and readers should hold the “topical wins on evidence” conclusion as a statement about what has been studied, not a proven verdict that topical outperforms injection.