Amazon.com: Copper Peptides Serum for Face Peptides Collagen Renewal & Anti Aging Serum GHK Cu, EGF, Hyaluronic Acid,Collagen Anti Wrinkle, Firming, Moisturizing Korean Skin Care,25mL 0.88 Fl Oz : Beauty & Personal Care GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? If your GHK injection site gets irritated try this , 1. Dilute it by adding more water to the syringe , 2. Let it sit until it reaches room temperature , Also, make sure youre rotating injection GHK CU, Why this audio? Because injecting feels like a constant wasp sting so it takes me about 15 seconds to pin .2 mL. I dread this shot every night for that reason. Also, it leaves me bruised, so I