Great question! I had to dig into this myself awhile back which is why I changed our recipe around to use the Timeless HA serum. The central reason is that we have a chemistry problem.
GHK-Cu is a copper peptide complex where a copper ion is bound (chelated) to a short chain of amino acids (Glycyl-L-Histidyl-L-Lysine). This bond is incredibly fragile.When you dump raw GHK-Cu powder into a cosmetic formula that wasn't explicitly built for it, you introduce two massive chemical conflicts:
Chelator Competition: Ready-made cosmetic serums often contain chelating agents (like Disodium EDTA, Tetrasodium Glutamate Diacetate, or Citric Acid) to trap stray minerals and preserve the product. Strong chelators will ruthlessly strip the copper ion away from your GHK peptide, thus essentially destroying it.
pH Mismatch: GHK-Cu requires a highly specific, neutral pH environment (typically between 6.0 and 7.0) to remain stable. Many of The Ordinary’s popular serums, especially their direct acids (Salicylic, Glycolic, Lactic) and Vitamin C solutions—have highly acidic pH levels. Putting GHK-Cu into an acidic serum triggers acid hydrolysis, which permanently breaks down the peptide bonds and renders the mixture useless.
According to the ingredient list for Timeless HA, this serum contains only four ingredients: Water, Sodium Hyaluronate (HA), Benzyl Alcohol, and Dehydroacetic Acid. It completely lacks strong heavy-metal chelators like Disodium EDTA, which means there is nothing in the bottle to strip the copper away from your GHK peptide. It also has a friendly pH.