Subcutaneous Injection: What Is It and How to Give One Ro GHK CU Beverly Hills Rejuvenation Center Subcutaneous Injection: What It Is and How to Give One Everything you need to know about GHK Cu WHAT IS IT? A copper peptide your body naturally produces but production drops by 60% by age 60. It's one of the most Redness after a peptide injection can feel alarming but in most cases, its completely normal. , If youve noticed a pink or red halo at the injection site especially with peptides like GHK Cu