A cyclic lactam analog of alpha-MSH that agonises melanocortin receptors non-selectively. MC1R activation on melanocytes drives eumelanin synthesis (tanning); MC4R activation in the CNS drives appetite suppression and erectile effects; MC3R and MC5R engagement adds further off-target activity. The lack of selectivity is the core problem — every effect arrives together, wanted or not.
Never completed clinical development. The selective successor bremelanotide (PT-141) was carried forward instead, and afamelanotide (a different MC1R-selective analog) was approved narrowly for erythropoietic protoporphyria. Melanotan II itself has no controlled efficacy evidence.
Not approved in any jurisdiction. Multiple national health agencies — including in the UK, Australia, and across the EU — have issued public safety warnings specifically against it. Sold illicitly online.
The clearest safety signal in this library. Documented in the case literature: changes in melanocytic naevi, including reports of melanoma diagnosed in users — a stimulator of melanocytes is not a benign thing to inject. Also reported: rhabdomyolysis, posterior reversible encephalopathy syndrome, priapism, severe nausea, and renal infarction. Unregulated supply means identity and purity are unverified on top of the pharmacology. This is not a peptide with theoretical concerns; it is one with published harm.
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Regulatory status changes. This page reflects our reading of public sources as of July 2026 and should be independently verified before it is relied upon.