Melanotan II
Melanotan II is a synthetic cyclic peptide and non-selective melanocortin-receptor agonist studied for pigmentation, which is unlicensed, sold illicitly, and the subject of UK MHRA safety warnings.
Melanotan II is a synthetic cyclic heptapeptide analog of the endogenous hormone α-melanocyte-stimulating hormone (α-MSH). It was originally developed in academic research as a tool for studying the melanocortin receptor system, and its structure — featuring a lactam bridge cyclization, an N-terminal acetyl group, a C-terminal amide, a non-standard norleucine (Nle) residue, and a D-phenylalanine substitution — was designed to increase potency and metabolic stability relative to native α-MSH.
Pharmacologically, Melanotan II is a non-selective agonist at the melanocortin receptors MC1R, MC3R, MC4R, and MC5R. Activation of MC1R on melanocytes stimulates eumelanin synthesis, producing skin darkening that is independent of ultraviolet exposure, while activation of central MC4R is associated with effects on appetite and sexual arousal. This broad, non-selective receptor activity distinguishes it from more selective analogs that were developed later, such as bremelanotide (PT-141), which arose from research on Melanotan II.
Regulatory status. Melanotan II is not an approved medicine. It is not FDA-approved for any indication and is not licensed in the UK or EU. The UK Medicines and Healthcare products Regulatory Agency (MHRA) has repeatedly stated that products containing Melanotan are unlicensed, illegal to sell and supply, and of unknown safety and quality, and it has acted to shut down suppliers. It should not be confused with the approved melanocortin drugs afamelanotide (Scenesse) and bremelanotide (Vyleesi).
Safety. Because Melanotan II is unlicensed and unregulated, the composition, purity, and dose of marketed products cannot be assured. The MHRA has received reports of suspected adverse reactions spanning stomach, heart, blood, and eye disorders. As it is typically self-injected (and sometimes used as a nasal spray), it carries infection and cross-contamination risks associated with non-sterile or shared needles. Published case reports describe rapid changes to moles and new or darkening pigmented lesions — which can be warning signs of skin cancer — along with nausea and oral mucosal pigmentation. Nasal-spray tanning formulations are specifically flagged as unsafe.
This entry is provided as a neutral scientific and regulatory reference. It is not medical advice and does not endorse human use.
Melanotan II is a synthetic cyclic heptapeptide analog of α-melanocyte-stimulating hormone (α-MSH) that acts as a non-selective agonist at melanocortin receptors (MC1R, MC3R, MC4R, MC5R). Agonism at MC1R on melanocytes drives eumelanin synthesis (pigmentation), while MC4R activity in the central nervous system is associated with effects on appetite and sexual arousal. A lactam bridge cyclization and a D-phenylalanine substitution increase its potency and enzymatic stability relative to native α-MSH.
- Human evidence
- Limited; small clinical/observational studies and adverse-event case reports only
- Regulatory status
- Not an approved medicine. NOT FDA-approved for any indication and not licensed in the UK or EU. The UK MHRA has repeatedly warned that products containing Melanotan are unlicensed, illegal to sell, and of unknown safety/quality, and has acted to close suppliers. Distinct from the approved melanocortin drugs afamelanotide (Scenesse) and bremelanotide (Vyleesi).
- Reference probe in melanocortin-receptor pharmacology research, particularly as a non-selective MC1R/MC3R/MC4R/MC5R agonist.
- Preclinical study of melanogenesis and UV-independent pigmentation pathways.
- Investigation of central melanocortin signaling related to appetite/energy homeostasis and sexual function in animal models.
- Comparator structure in medicinal-chemistry work that led to selective analogs such as bremelanotide.
- UK MHRA warns Melanotan products are unlicensed and illegal to sell, with no guarantee of safety, quality, or efficacy; it has received reports of suspected adverse reactions including stomach, heart, blood, and eye disorders (MHRA; via Cancer Research UK).
- Because it is typically self-injected (or used as nasal spray), it carries risks of cross-contamination and infection from shared or non-sterile needles (NHS / Cancer Research UK).
- Case reports describe rapid changes to moles and new/darkening pigmented lesions, which can be signs of skin cancer, as well as nausea and oral mucosal pigmentation (case reports; PMC case report).
- Nasal-spray tanning formulations are specifically flagged as unsafe and should not be used (Cancer Research UK).
- [1]PubChem CID 92432 — Melanotan IIPubChem
- [2]Tanning, fake tan and MelanotanCancer Research UK
- [3]Changes in Oral Mucosa Associated with Melanotan II Injections: A Case ReportPMC / NCBI
- [4]Melanotan IIDermNet NZ