Melanotan II (MT-II) Overview

Melanotan II (MT-II) is a synthetic, cyclic peptide developed as an analogue of α-melanocyte-stimulating hormone (α-MSH). It works as a non-selective melanocortin receptor agonist, meaning it can activate multiple melanocortin receptors involved in pigmentation and other physiologic effects. (The International Peptide Society)

MT-II is best known for its ability to stimulate melanin production (tanning) in humans, but it is also associated with a range of systemic side effects and safety concerns, especially when used via unregulated products. (PubMed)

Pigmentation and “Tanning” Effects

Increases melanin production and visible pigmentation

Early clinical pharmacology research demonstrated that MT-II can produce tanning activity in humans after a limited number of subcutaneous doses in controlled research conditions. (PubMed)

Important context: demonstrating tanning activity is not the same as proving long-term safety—particularly for products sold outside regulated clinical manufacturing and medical supervision. (DermNet®)

Mechanism of Action

MT-II is described in the scientific literature as a melanocortin receptor agonist (often discussed across MC1R/MC3R/MC4R/MC5R activity). Pigmentation is primarily linked to melanocortin signaling in the skin (classically MC1R), while other receptor activity is associated with non-pigment effects (e.g., appetite/sexual side effects discussed in reports). (The International Peptide Society)

Safety, Adverse Effects, and Regulatory Concerns

Commonly reported short-term effects

Medical dermatology references describe short-term effects such as nausea, flushing, reduced appetite, and (in males) spontaneous erections, with concern for prolonged erections/priapism. (DermNet®)

Serious adverse event reports (case literature)

Peer-reviewed case reports and reviews describe serious events temporally associated with MT-II use, including ischemic priapism and renal infarction/kidney injury. (PMC)

Skin lesion changes and melanoma concern

Dermatology sources warn about new or changing moles, darkening lesions, and melanoma concern, particularly given melanocortin stimulation combined with UV exposure behaviors that often accompany “tanning” use. (DermNet®)

Public health warnings about unregulated products

Regulators and clinical organizations have issued safety communications warning against melanotan products due to reported adverse effects, product variability/contamination risk, and potential long-term harms. (Therapeutic Goods Administration (TGA))

Not FDA-approved / enforcement history

FDA records document concerns with marketing Melanotan II (MII) as an unapproved “new drug” without an approved application, reflecting the regulatory status and enforcement posture toward such products. (U.S. Food and Drug Administration)

Melanotan II Specifications

From NIH PubChem and FDA’s GInAS entry for the substance:

• CAS Number: 121062-08-6 (PubChem)

• Molecular Formula: C₅₀H₆₉N₁₅O₉ (PubChem)

• Molecular Weight: ~1024.2 g/mol (PubChem)

• Peptide type: cyclic melanocortin analogue / melanocortin receptor agonist (The International Peptide Society)

(Note: supplier listings sometimes also reference salt forms such as acetate, which can differ in formula/mass.)(PubChem)

Important Notice

Melanotan II is not an FDA-approved medication for cosmetic tanning, and it is frequently encountered in unregulated products (injections, nasal sprays, etc.) with significant safety concerns. Any description intended for commerce should remain consistent with in vitro research-only positioning and should not present MT-II as a drug, supplement, cosmetic, or food product. (U.S. Food and Drug Administration)

References

1. Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide, in humans (tanning activity). PubMed record (1996). (PubMed)

2. DermNet NZ. Melanotan II (side effects; mole changes; melanoma concern; rhabdomyolysis/encephalopathy warnings). (DermNet®)

3. Therapeutic Goods Administration (Australia). Don’t risk using tanning products containing melanotan (Jan 24, 2025). (Therapeutic Goods Administration (TGA))

4. Health Products Regulatory Authority (Ireland). Reminder of serious health risks with Melanotan 2 self-tan products (Aug 10, 2023). (HPRA)

5. Peters B, et al. Melanotan II: possible cause of renal infarction (case report/review). BMJ Case Reports / PMC(2020). (PMC)

6. Dreyer BA, et al. Melanotan-induced priapism (case report). BMJ Case Reports / PMC (2019). (PMC)

7. Mallory CW, et al. Melanotan tanning injection: a rare cause of priapism (case report). Urology Case Reports(2021). (ScienceDirect)

8. FDA docket document referencing FDA warning letter concerns about marketing MII as an unapproved new drug. (U.S. Food and Drug Administration)

9. NIH PubChem. Melanotan II compound record (CAS, formula, molecular weight). (PubChem)

10. FDA GInAS substance entry. MELANOTAN II (formula and molecular weight). (precision.fda.gov)

Complete Disclaimer

This product is sold exclusively for laboratory research purposes under Section 351 of the Public Health Service Act. It is not intended for human or veterinary use, nor for diagnostic, therapeutic, or cosmetic applications. Purchaser certifies they are properly licensed and equipped to handle research compounds in compliance with all local, state, and federal regulations. EaglePeptidesUSA assumes no liability for misuse or unauthorized handling. By purchasing, you affirm this material will not be introduced into interstate commerce or used in food/drug products.