Melanin is the pigment responsible for skin colour, and inhibiting its production can result in a lighter complexion
Adding to doctors worries are concerns about purity and dosing, because users typically buy from websites selling unregulated Chinese product some of which comes from plants that previously produced the deadly opioid fentanyl
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Full description GHK-Cu (glycyl-L-histidyl-L-lysine copper) is a natural tripeptide complex 'glycine + histidine + lysine' bound with copper ion (Cu)

Key Ingredients Salmon Collagen Peptide 1,000mg, Liposomal Glutathione 100mg, Elastin 10mg, Hyaluronic Acid 10mg, Vitamin C Full Ingredients Purified water, white sugar, liquid fructose, peach concentrate (peach 100%, Israeli) 10%, fructooligosaccharide, salmon collagen (Norwegian), citric acid (acidity regulator), malic acid (acidity regulator), Vitamin C (nutrient fortifier), calcium dihydrogen phosphate (nutrient fortifier), mixed preparation (gum mix: xanthan gum, agar, carrageenan, locust bean gum, tamarind gum, dextrin, tara gum), guar gum, liposomal L-glutathione yeast 9 [dextrin, yeast food (yeast extract 100%)], lecithin, citric acid, elastin (elastin hydrolysate 100%), hyaluronic acid mixed powder (hyaluronic acid, dextrin), enzyme-treated stevia, peach flavour, yogurt flavour Contains: Soy Manufactured in a facility that also processes milk, wheat, peanuts, buckwheat, mackerel, crab, shrimp, pork, tomato, sulphites, abalone, squid, shellfish (oyster, abalone, mussel), chicken, beef, and peach

A few found it expensive, and one reported unexpected weight gain