A change in any mole — size, shape, colour, an irregular border, or bleeding — is the signal that matters most here. Also: severe nausea, or a painful prolonged erection.
Photograph any changing mole and get it seen by a dermatologist promptly — do not wait for a routine appointment. Melanoma has been reported in users.
An erection lasting over ~4 hours (priapism) is a urological emergency. Severe headache with vision change or a seizure (possible PRES), or muscle pain with dark urine (rhabdomyolysis) → 911.
Allergic reaction: hives, swelling of the lips, tongue or throat, wheezing or dizziness can escalate to anaphylaxis within minutes — call 911 immediately. Site infection: spreading redness, heat, swelling, pus or fever is not wait-and-see; an abscess or cellulitis can need drainage or IV antibiotics. Unverified product: grey-market vials are frequently mislabelled or contaminated, so a reaction may be to endotoxin or the wrong contents, not the named compound.
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.
No approved dose and no validated trial regimen exists. Multiple national health agencies warn against using it at all.
Reported from clinical trials or FDA labelling as a matter of record. It is not a recommendation, and for unapproved compounds no dose has been shown safe or effective in humans.
Above is what was administered in trials or on FDA labels, reported as fact. We do not convert it into a personal protocol, calculate a dose for your body weight, or tell you what to inject or how to reconstitute it — that decision belongs with a licensed physician. See our editorial policy.
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.