HUBERMAN: So the point is that if you want a specific biological effect, maybe you want to repair a given injury, or you'd like to get more growth hormone in order, I don't know, to get leaner or to recover from exercise more quickly or to feel more vitality, yes, there are peptides that can impact those pathways, but always, always, always, if you take peptides, especially therapeutic peptides, designed to promote activity within a given pathway for a specific purpose, you are going to activate other pathways as well
People use it to promote healing and reduce inflammation, especially in muscles and the digestive system
[DOI] [PMC free article] [PubMed] [Google Scholar] [10].Moloney RD, Desbonnet L, Clarke G, Dinan TG, Cryan JF

Visual signs of degradation Injectable GHK-Cu changes: Clear to cloudy (bacterial growth or precipitation) Color change (bluish, greenish tint from copper oxidation) Particles floating in solution Separation or settling Topical serum changes: Darker color (oxidation) Layer separation Texture changes (thicker or thinner) Crystallization Powder changes: Color darkening Clumping (moisture absorption) Greenish or bluish tint Loss of fine powder consistency Smell and texture changes Off odors: Metallic smell intensifying (some metallic odor is normal for copper peptides) Sour or rancid smell (bacterial contamination or lipid oxidation in serums) Any unusual smell different from when first opened Texture issues: Serum becoming grainy Unusual thickness or thinning Sticky residue Separation that doesn't re-mix Effectiveness loss Signs of reduced potency: Reduced healing speed (injectable) Less visible skin improvement (topical) Need to use more product for same effect Complete lack of expected results When in doubt: Discard and get fresh product

I use the vitamin C to improve my skin tone and reduce bruising (from medication I take)
Try keeping track of exactly how much vitamin B12 you are consuming on a weekly basis and promptly consult your primary care physician if you start experiencing any adverse symptoms, like trouble sleeping at night or gastrointestinal discomfort you might want to lower your dosage if nothing else but your weekly vitamin B12 consumption has changed