Melanotan II

Melanotan II (MT-II) is a synthetic peptide analog of the naturally occurring alpha-melanocyte-stimulating hormone ((\alpha )-MSH). It is designed to stimulate tanning by increasing melanin production, often sold as injections or nasal sprays, and is recognized as a cyclic heptapeptide that acts on melanocortin receptors.

Key Benefits

• May support increased skin pigmentation and tanning with reduced sun exposure
• Commonly researched for promoting a more even and longer-lasting tan
• May help support libido and sexual function in some individuals
• Research suggests potential benefits for skin appearance and UV-related skin protection mechanisms

Uses

Conditions where Melanotan II has been clinically studied:

• Skin tanning (Phase 1 clinical study completed — Dorr et al. 1996)
• Erectile dysfunction (Phase 2 completed — Wessells et al. 2000)
• Prevention of skin cancer from sun exposure (proposed; not completed)
• Rosacea (proposed; limited data)
• Fibromyalgia (proposed; limited data)

Trade Names in USA and Manufacturers

Discovery and development history:

• Synthesized at the University of Arizona (Tucson, AZ) in the late 1980s by Prof. Mac Hadley, Prof. Victor Hruby, and colleagues
• Originally developed as a potential tanning agent and melanoma prevention tool
• Competitive Technologies licensed Melanotan I (tanning) to Epitan/Clinuvel and Melanotan II (sexual dysfunction) to Palatin Technologies
• Palatin ceased Melanotan II development in 2000; subsequently developed bremelanotide (PT-141/Vyleesi) — a likely metabolite of MT-2 with a carboxy group instead of an amide — which became FDA-approved in 2019

Molecular identity:

• Synthetic cyclic heptapeptide (7 amino acids in closed ring)
• Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂
• MW: ~1,024 Daltons
• Shares the same cyclic peptide scaffold as bremelanotide (PT-141) with one key difference: amide (-NH₂) vs. carboxy (-OH) at C-terminus

Dosage

LOADING PHASE (Weeks 1–3):

• Starting dose: 0.25 mg SC once daily (first 2–3 days to assess nausea tolerance)
• Standard loading: 0.5 mg SC once daily
• Total loading duration: 2–3 weeks until desired pigmentation level achieved
• UV exposure during loading: Low-level UV exposure (outdoor or tanning bed) accelerates pigmentation

MAINTENANCE PHASE:

• Dose: 0.5–1 mg SC once or twice weekly
• (Once desired tan level achieved; significantly less product needed)

Clinical study reference doses:

• Phase 1 tanning study (Dorr et al., 1996): 0.025 mg/kg SC doses
• Phase 2 erectile dysfunction study (Wessells et al., 2000): 0.025 mg/kg intranasal (~1.75 mg for 70 kg)

Nasal spray (grey-market ‘tan jabs’):

• Sold online; doses vary widely; efficacy and safety completely unverified
• Nasal bioavailability for MT-2 not established

Reconstitution (injectable vials):

• Lyophilized powder (typically 10 mg/vial)
• Add 2 mL Bacteriostatic Water → 5 mg/mL working solution
• Store lyophilized at -20°C; reconstituted solution refrigerated; use within 28 days

Pricing

10 mg vial: ~$20–$50
Monthly cost (loading phase, 0.5 mg/day): ~$30–$80/month
Monthly cost (maintenance, 1 mg/week): ~$10–$25/month
[Among the most affordable research peptides per dose due to small amounts needed for maintenance]

Note: Very small maintenance doses required (0.5–1 mg/week) make this relatively inexpensive per month after loading. However, the safety risks are significant regardless of cost.

Tips

• FDA-approved alternatives exist for MT-2’s primary applications: Afamelanotide (Scenesse) is FDA-approved — but only for erythropoietic protoporphyria; not for cosmetic tanning. For sexual dysfunction/HSDD: Bremelanotide (Vyleesi/PT-141) is FDA-approved for women with HSDD — a cleaner, better-studied option
• If libido/ED is the goal: PT-141 (bremelanotide) is FDA-approved, commercially available, and has an established safety profile vs. unapproved MT-2
• MOLE MONITORING IS MANDATORY: If using MT-2, baseline dermatological examination and regular monitoring of all moles is essential. Any new, changing, or unusual mole must be evaluated by a dermatologist immediately. Do NOT use if you have any pre-existing atypical moles, a history of melanoma, or family history of melanoma.
• Social media ‘tan jabs’ / tanning nasal sprays: These products are unregulated, unverified, and actively flagged by UK CTSI and FDA. A 2015 analysis found MT-2 products at only 43% labeled dose; sterility is not guaranteed.
• Monitor the July 2026 PCAC review outcome carefully — given the significant safety signals associated with MT-2, the PCAC decision may be more restrictive than for other peptides reviewed in July 2026.

Side Effects

Significant and well-documented side effect profile from Phase 1–2 clinical trials, case reports, and community use:

Very common (>10% in clinical studies):
– Nausea: Most common; occurs rapidly post-injection; dose-dependent; can be severe
– Flushing / warmth: Occurs shortly after injection; very common
– Fatigue / drowsiness: Common; MC4R-mediated central effect
– Spontaneous erections (men): Documented in 17% of men in Phase 2 trial — can be prolonged and painful (priapism risk)
– Compulsive yawning and stretching: Characteristic and well-documented; mechanism not fully understood but linked to central MC4R activation

Common (2–10%):
– Decreased appetite: MC3R/MC4R hypothalamic effect; may be severe in some users
– Headache
– Dizziness
– Abdominal pain / GI discomfort

Skin-related (significant safety concern):
– Darkening of pre-existing moles: Well-documented; reversible in most but not all cases
– New mole formation: Documented in multiple case reports
– Change in mole size, shape, or color: Requires immediate dermatological evaluation
– Melanoma: Multiple case reports in the medical literature. Causality debated (2013 review: ‘no conclusive evidence’; 2021 review: increased melanoma risk likely explained by associated UV-seeking behavior). Risk is UNRESOLVED.

Cardiovascular:
– Blood pressure elevation: Documented; dose-dependent
– Elevated heart rate
– Priapism (prolonged painful erection): Medical emergency requiring immediate treatment; permanent penile damage possible if untreated

Contraindications

Based on clinical trial data, case reports, and pharmacology:

Absolute avoid:
– Personal or family history of melanoma or atypical nevi
– Pre-existing atypical or dysplastic moles (without prior full dermatological evaluation)
– Uncontrolled hypertension or cardiovascular disease: BP elevation with each use
– Men with risk of priapism (sickle cell disease, multiple myeloma, leukemia, or use of medications that cause erections): Priapism risk — medical emergency
– Fair-skinned individuals (Fitzpatrick Skin Type I–II): Highest risk of mole changes and adverse pigmentation events
– Pregnancy and breastfeeding: No safety data; MC receptor effects are widespread

Strong caution:
– Any personal or family history of any skin cancer
– Patients with blood pressure disorders: BP monitoring required
– Men with any erectile dysfunction or urological history: Prolonged erection risk
– Patients taking medications that may interact with melanocortin pathways (e.g., antidepressants acting on serotonin system)
– Hypersensitivity to Melanotan II or components

Pharmacology

Melanotan II (MT-2) is a synthetic cyclic heptapeptide (7 amino acids; closed ring structure) and non-selective agonist of melanocortin receptors (MCR). Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂. MW ~1,024 Daltons. Developed at the University of Arizona in the late 1980s.

Relationship to other melanocortin drugs:
– Precursor relationship: MT-2 is structurally related to bremelanotide (PT-141/Vyleesi) — which is a likely metabolite of MT-2 with -OH replacing -NH₂ at C-terminus. PT-141 is FDA-approved (2019) for HSDD.
– Afamelanotide (Melanotan I / Scenesse): FDA-approved (2019) for erythropoietic protoporphyria; MC1R-selective; different molecule from MT-2.

Pharmacological selectivity profile:
MT-2 is non-selective across four melanocortin receptors:
– MC1R: Expressed on melanocytes → tanning (melanin production)
– MC3R: Hypothalamic → energy homeostasis, appetite
– MC4R: Hypothalamic and CNS → appetite (satiety), sexual arousal, blood pressure
– MC5R: Sebaceous glands, exocrine function, immune modulation

Mechanism of action

Melanotan II activates four melanocortin receptors with distinct physiological consequences at each receptor:

1. MC1R activation (melanocytes in skin and mucosa):
→ Stimulates tyrosinase activity → increases eumelanin (dark, UV-protective melanin) production over pheomelanin (lighter, less protective)
→ Produces tan/darkening of skin, mucous membranes, and existing moles
→ Also responsible for persistent focal hyperpigmentation and new mole formation

2. MC4R activation (hypothalamus, CNS — primary for sexual effects):
→ Increases dopamine signaling in mesolimbic pathway → sexual arousal and desire
→ Produces satiety signals → decreased appetite and food intake
→ Contributes to blood pressure regulation (central sympathetic activation)
→ Mechanism of spontaneous erections in men (central dopaminergic arousal pathway)
→ Same receptor targeted by PT-141 (bremelanotide/Vyleesi) for FDA-approved HSDD treatment

3. MC3R activation (hypothalamic):
→ Energy homeostasis modulation
→ Contributes to appetite suppression
→ May contribute to sexual arousal (working in conjunction with MC4R)

4. MC5R activation (sebaceous glands, immune):
→ Exocrine gland function modulation
→ Minor immunomodulatory effects

Key clinical consequence of non-selectivity:
Unlike PT-141 (which primarily targets MC1R and MC4R) or afamelanotide (MC1R selective), MT-2’s activation of all four receptors simultaneously produces a broader and less predictable side effect profile — the reason FDA-approved derivatives are more selective by design.

Result Claims By Different Companies

University of Arizona research group (Hadley, Hruby et al.) and clinical investigators:

Phase 1 tanning study (Dorr et al., Life Sciences, 1996):
– Demonstrated dose-dependent melanotropic activity (skin darkening) in human volunteers
– First clinical evidence of MT-2 efficacy in humans
– Nausea as primary dose-limiting side effect identified

Phase 2 erectile dysfunction study (Wessells et al., Journal of Urology, 2000):
– Intranasal MT-2 (0.025 mg/kg) in men with organic ED
– Statistically significant improvement in erections vs. placebo
– 17% of men experienced spontaneous erections
– High nausea rate limited further development
– These results led Palatin to pursue the modified metabolite bremelanotide (PT-141) as a cleaner alternative

Melanotan I / Afamelanotide (related compound; FDA-approved 2019):
– MC1R-selective (unlike MT-2’s non-selective profile)
– FDA-approved for erythropoietic protoporphyria
– Demonstrates proof of concept that MC1R targeting for pigmentation is clinically achievable safely

Case report literature (concern):
– Multiple published case reports of melanoma, eruptive nevi, and atypical nevi associated with MT-2 use (Hjuler et al., JAAD, 2014; Sivyer et al., Case Rep Dermatol Med, 2013)
– 2013 review: ‘No conclusive evidence’ MT-2 causes melanoma
– 2021 review: ‘Increased risk of melanoma in Melanotan users can probably be explained by more UV exposure’

UK CTSI formal warning (2025): Life-threatening health risks; unregulated products; no guarantee of purity or dosing.

Disclaimer

This content about “Melanotan II is for informational and educational purposes only, is not medical advice, does not replace consultation with a licensed healthcare professional, and affiliate links may result in compensation at no additional cost to you.