Melanotan II (Tan Jabs): Why They're Not Worth The Risk Peptides for tanning do exist. Melanotan 1 and Melanotan 2 both work at increasing melanin in the skin. Melanotan 1 takes longer to activate. Melnotan 1 is FDA approved. Melanotan 2 does libido, Been testing out MT 1 peptide (Melanotan I) lately and honestly this stuff works. Originally developed for skin protection and UV resistance, but most people know it now for boosting melanin and giving How Long Does It Take For Melanotan To Work? Insights into Tanning Biology and Tanning Products JCAD The Journal of Clinical and Aesthetic Dermatology