liposomal glutathione pure health Encapsulations - Immune Support & Liver Detox* - Antioxidant Protection - With Setria Glutathione - Non-GMO Liposomal Glutathione Supplement 500mg -

Bibcode:1955Natur.176..325H

Given that GHK-Cu is a naturally occurring molecule present in human plasma, concerns about long-term topical use seem largely theoretical

doi:10.1146/annurev.nu.05.070185.000555

Dosage, reconstitution protocols, and sterile technique decisions should be made in consultation with institutional research oversight or qualified professionals familiar with peptide handling standards

The technique, timing, and storage requirements are consistent across these GLP-1 class peptides

I think if you're at a frequency that suits you, you roll along feeling OK, unless something rocks the boat, like an infection or overdoing it for example