The easiest thing to do in this situation is to stop taking the supplement and see if your skin improves
Based on studies of electrical stimulation in the normal brain and in disease (human and animal models), there is a general consensus that stimulating the cerebellum has profound effects on behavior
For topical applications Some users reconstitute GHK-Cu for topical rather than injectable use
GHK-Cu (skin, hair, inflammation) Article: GHK-Cu studied for skin, hair and healing GHK-Cu is a naturally occurring copper-binding peptide discovered in human plasma that activates thousands of genes involved in healing, reducing inflammation, and protecting against oxidative stress
Conclusion To answer the original question directly: high B12 levels themselves don't typically cause symptoms
an unusual or allergic reaction to cyanocobalamin, cobalt, other medicines, foods, dyes, or preservatives