Its 180,000+ studies over decades
The copper content of GHK-Cu formulations has been a theoretical safety consideration, given that excessive copper can be toxic - however, the amounts used in cosmetic and research applications are extremely small, the copper is tightly chelated by the peptide (reducing free copper availability), and topical absorption of copper from these products appears minimal and well below levels that would cause systemic copper accumulation or toxicity
predicted significantly worse patient survival (117)
Renal injuries were scored as follows: 0, no change
DOI Maquart FX, Pickart L, Laurent M, et al
IV Hydration IV Hydration IV hydration therapy delivers fluids, electrolytes, and nutrients directly into the bloodstream for rapid absorption and revitalization