Subcutaneous Injection Sites and Instructions for Safe Self Administration The tripeptide GHKCu complex ameliorates lipopolysaccharideinduced acute lung injury in mice Oncotarget For subcutaneous injections, using shorter needles (4 5mm) is the safest choice to ensure medication stays in the fatty layer and avoids muscle injury. A 4mm needle is ideal, minimizing pain while keeping GHK Cu Copper Peptide Benefits, Uses & Safety Intra V Ghk Cu Intra Nasal Spray 50 mg 0.34 oz.