Potential for Kidney Problems High doses of L-carnitine over long periods could potentially strain the kidneys, particularly in individuals with pre-existing kidney conditions
However, as reassuring as all of this is, there are a couple of things to remain mindful of: Copper toxicity Because GHK-Cu contains copper, it does pose a potential risk of copper toxicity,12 the symptoms of which include abdominal pain, vomiting, chest pain, chills, cough, fever, general weakness, anemia, burning sensations, tremors, and a metallic taste in the mouth.13 The risk is small, as the concentrations of copper in the peptide are typically well within safe parameters, but its good to be aware of it
doi: 10.1093/nutrit/nuad082
"CuZnSOD deficiency leads to persistent and widespread oxidative damage and hepatocarcinogenesis later in life"
For optimal results, combine both approaches