Overview
Melanotan II (MT-2) is a synthetic cyclic heptapeptide developed in the late 1980s at the University of Arizona alongside its less-promiscuous sibling Melanotan I. Unlike MT-1 (which became the FDA-approved drug afamelanotide / Scenesse for erythropoietic protoporphyria), MT-2 was eventually abandoned as a pharmaceutical candidate but became — and remains — one of the most heavily community-used research peptides on the gray market, primarily for its ability to drive deep cosmetic tanning. The same non-selective melanocortin-receptor activity that made it a tanning agent also produces a meaningful safety burden: priapism (MC4R-mediated, the same mechanism that makes the related compound bremelanotide / PT-141 effective for HSDD), nausea, blood pressure spikes, and changes in pigmented skin lesions that have raised melanoma surveillance concerns. This entry must lead with the safety flags.
Mechanism
Non-selective agonist at all four melanocortin receptors expressed in skin and the CNS: MC1R (drives melanogenesis — the cosmetic tanning effect), MC3R / MC4R (modulates appetite, sexual function, and blood pressure — the source of the priapism, nausea, and BP effects), and MC5R (sebum, less clinically prominent). The non-selectivity is the key differentiator from MT-1 (more selective for MC1R) and from PT-141 / bremelanotide (developed specifically as a more selective MC4R agonist for sexual function).
Evidence by indication
We classify each indication separately. The same peptide can be Tier 1 for one use and Tier 4 for another. Tiers reflect the published literature, not the strength of community framing.
Cosmetic tanning
MT-2 reliably drives melanogenesis in users — that biological effect is real and replicated in early-phase human work. Cosmetic tanning is not a regulator-approved indication, no controlled trial has established safe long-term dosing, and the safety burden (priapism, melanoma surveillance, BP, nausea) is substantial in a population using it for cosmesis rather than medical necessity.
Erectile / sexual function (community / off-label)
MC4R activation is clinically validated for sexual function via the related, more-selective drug bremelanotide / PT-141 (FDA-approved 2019 for HSDD in women). MT-2's non-selectivity drives meaningful adverse effects including priapism, which is the reason a more-selective compound was developed. Use of MT-2 for sexual function is mechanism-as-evidence with worse safety than the actually approved compound.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Appetite suppression / weight loss
MC4R activation suppresses appetite — MT-2 does cause meaningful early-dose anorexia. Not pursued clinically as a weight-loss agent (the GLP-1 class displaced this and other melanocortin approaches). Mechanism is real, clinical-outcome data is essentially absent.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Studied dose ranges
The ranges below come from published trial protocols where available, and from documented self-experimenter consensus where the literature does not include human dose-finding work. The notes flag which is which.
Community 'loading then maintenance' protocols are not based on dose-finding clinical trials. Start at the very low end (e.g., 100–250 mcg) to assess tolerability — initial doses commonly cause significant nausea and flushing.
Contraindications
- Personal or family history of melanoma or significant atypical-mole syndrome — STRONG contraindication; cases of melanoma developing during MT-2 use have been reported in the dermatology literature
- Pre-existing erectile-priapism risk (sickle cell trait/disease, cavernosal pathology)
- Uncontrolled hypertension (BP elevations reported)
- Cardiovascular disease (BP and tachycardia effects)
- Pregnancy and breastfeeding
- Significant pre-existing pigmented lesions requiring monitoring
- Hypersensitivity to peptide formulations or excipients
Reported side effects
- Nausea, especially with initial doses (often significant)
- Flushing, dizziness
- Spontaneous penile erection / priapism (MC4R-mediated; can be prolonged and require medical intervention)
- Increased blood pressure
- New or darkened nevi (mole surveillance is essential during and after use)
- Reports of melanoma developing during MT-2 use (causation vs surveillance bias contested; the signal warrants serious caution)
- Yawning, drowsiness post-injection
- Decreased appetite
- Long-term safety in chronic recreational use is unknown
Reconstitution & storage
Lyophilized powder reconstituted with bacteriostatic water. A 10 mg vial in 5 mL BAC water = 2 mg/mL, making a 250 mcg dose ~12.5 units on a U-100 syringe. Use the Juno calculator to verify. Initial dose should be the lowest possible volume (~50 mcg) to assess tolerability.
Storage. Lyophilized: refrigerate. Reconstituted: refrigerate 2–8 °C, use within 30 days.
Open the peptide calculator → to compute exact draw volumes for your specific vial and BAC water choice.
Editorial note
DRAFT — pending Wayne's review. MT-2 is the entry where 'community popularity does not affect tier and absolutely does not soften safety' has to land. Lead with the safety flags. The melanoma reports in the dermatology literature are not proof of causation but the surveillance signal is real, and dermatology specialists generally counsel against MT-2 use for cosmetic tanning. Disambiguate explicitly from MT-1 / Scenesse (the FDA-approved sibling). Pair with PT-141 entry — PT-141 is the more selective MC4R agonist developed specifically because MT-2's non-selectivity caused priapism and BP issues.
Citations
- [1]Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical studyDorr RT, Lines R, Levine N, et al. · Life Sciences · 1996 · PMID 8841168Anchor early Phase I work characterizing pharmacology and the priapism/nausea side-effect profile.View source
- [2]The use of melanotan injections for tanning: A literature reviewHabbema L, Halk AB, Neumann M, Bergman W. · Journal of Cosmetic Dermatology · 2017 · PMID 30171848Safety-focused literature review including reports of melanoma during MT-2 use; supports the cautionary editorial framing.View source