Is it necessary to cycle on and off of every peptide? The answer may not be as simple as you think, and it depends on *why* the peptide is being used., The standard logic for cyclingusing something GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? The GHK Cu pen works. But needles at home were never the answer. We took the same clinically backed copper peptide complex and put it into a serum you can use in 30 seconds, 7% GHK CU ACCELERANT Platinum Skin Care