CalcMyPeptide
Skin & CosmeticAlso known as: MT-2, Melanotan 2

Melanotan II

Melanotan II (MT-2) is a brutally potent alpha-melanocyte-stimulating hormone (α-MSH) analog originally designed to prevent UV-induced skin cancer. Widely infamous as the "Barbie Drug," it aggressively forces melanogenesis—creating deep, protective pigmentation with absolute minimal UV exposure. Beyond intense photoprotection, it is a highly volatile, multi-receptor peptide that notoriously triggers immediate, involuntary erections, intense nausea, and powerful appetite suppression, making its dosing curve notoriously difficult to navigate.

Reviewed by CalcMyPeptide Editorial Team
Last updated: April 2026Evidence: Moderate1 peer-reviewed citation

Quick Stats

Half-Life~1 hour
Dose Range250-500 mcg/day (loading)
FrequencyDaily (loading 2 weeks), then 1-2×/week maintenance
Vial Sizes10 mg
Bioavailability~100% (subcutaneous)
Year Developed1981

Scientific Data

Molecular Formula
C50H69N15O9
Molecular Weight
1024.18 g/mol
CAS Number
PubChem ID
Developer
University of Arizona (Victor J. Hruby lab)

Mechanism of Action

Melanotan II (MT-2) is a synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH) that activates multiple melanocortin receptors. MC1R activation stimulates melanocytes to produce melanin, resulting in skin darkening (tanning) without UV exposure. MC3R/MC4R activation produces sexual arousal effects (the pathway that led to PT-141 development) and appetite suppression.

MT-2 is a non-selective melanocortin agonist, which means it produces multiple effects simultaneously: tanning, sexual function enhancement, and modest appetite reduction. The tanning effect is cumulative and persists for weeks to months after discontinuation.

Source: PMID: 10221658

Background & History

Melanotan II (MT-2) was developed at the University of Arizona in the 1980s–90s by Mac Hadley and colleagues seeking a method to induce melanogenesis without UV exposure for skin cancer prevention. It is a cyclic analog of alpha-MSH with 1000× greater potency than natural α-MSH at MC1R. Serendipitously, researchers discovered its potent sexual arousal and appetite suppression effects via MC4R activation. It has never received regulatory approval and is considered a research compound.

Research Use Cases

  • Tanning/melanogenesis without UV radiation
  • Erectile dysfunction and sexual arousal (via MC4R)
  • Appetite suppression for weight management

Dosing Protocol

Typical Dose250-500 mcg/day (loading)
FrequencyDaily (loading 2 weeks), then 1-2×/week maintenance
Half-Life~1 hour
Common Vial Sizes10 mg

Dosing Protocols

Loading Phase

Dose
250 - 500 mcg
Frequency
Daily for 2 weeks
Note: Inject before bed. Start at 100-250 mcg if nausea-sensitive during loading.

Maintenance Phase

Dose
250 - 500 mcg
Frequency
1-2x per week
Note: Brief UV exposure (10-15 min) enhances melanin activation.

Body-Weight Dosing Reference

Estimated doses extrapolated from the published research range of 250500 mcg/day (referenced to 70 kg / 154 lb). These are approximations — consult a qualified healthcare provider for personalised guidance.

WeightLowTargetHigh
120 lb(54 kg)193 mcg289 mcg386 mcg
140 lb(63 kg)225 mcg338 mcg450 mcg
160 lb(73 kg)261 mcg391 mcg521 mcg
180 lb(82 kg)293 mcg439 mcg586 mcg
200 lb(91 kg)325 mcg488 mcg650 mcg
220 lb(100 kg)357 mcg536 mcg714 mcg
250 lb(113 kg)404 mcg605 mcg807 mcg

💉 For exact syringe units based on your vial concentration, use the Melanotan II Reconstitution Calculator →

Administration

Route
Subcutaneous injection
Timing
Before bed to minimize nausea impact. Fasting not required.
Fasting Required?
No — food timing not critical

Expected Timeline

Week 1-2 (Loading)
Gradual skin darkening begins. Nausea most prevalent in this window.
Week 3-4
Visible tan develops. Nausea typically subsides as loading completes.
Maintenance
Tan sustained with 1-2 doses/week. Persists weeks-months after stopping.

Who Is It For?

Skin Tanning

High

Strong melanin production with or without UV. Tan persists after cycle ends.

Sexual Function Enhancement

Moderate

MC4R activation produces arousal effects — the pathway that led to development of PT-141.

Reconstitution Example

Vial
10 mg
Water
2 mL
Concentration
5 mg/mL
Per Unit (100u syringe)
50 mcg
Dose of 250 mcg = 5 units on a 100-unit insulin syringe

Safety & Considerations

Research peptide — not FDA-approved. Monitor existing moles for changes. Common: nausea (loading phase), facial flushing, spontaneous erections (males). Not for use with history of melanoma.

Regulatory & Legal Status

FDA Status (US)
Research Only
WADA Status (2026)
Not Listed

Not currently on the WADA 2026 Prohibited List. Policies may change — verify before competition.

Classification

Research Chemical

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Interactions & Contraindications

MC1R activation causes mole darkening and new nevus formation — regular dermatological monitoring essential. Nausea common especially at higher doses. Spontaneous erections in men at standard doses. Do not use with cardiovascular disease. Use cautiously in patients with history of melanoma — theoretical risk of activating dormant melanocytes.

Synergies & Common Stacks

PT-141 is a more selective MC4R agonist derived from MT-2 with reduced melanogenic side effects — often preferred over MT-2 for pure sexual function goals.

Dosing Quick Reference

Melanotan II— Dosing Guide
Dose Range
250-500 mcg/day (loading)
Half-Life
~1 hour
Frequency
Daily (loading 2 weeks), then 1-2×/week maintenance
Route
Subcutaneous
10 mg vial
💧 2 mL BAC water📐 5 mg/mL concentration💉 50 mcg/unit (100u syringe)
Skin & Cosmeticcalcmypeptide.com

Frequently Asked Questions

How does the Melanotan II loading phase work?
Loading: 250-500 mcg daily for 2 weeks. Maintenance: 250-500 mcg 1-2x weekly. Brief UV exposure (10-15 min) enhances activation.
Do I still need sun exposure with Melanotan II?
UV enhances MT-2 results but is not mandatory. Noticeable darkening can occur without UV over a full loading period.
Is Melanotan II the same as Melanotan I?
No. Melanotan I (Afamelanotide/Scenesse) is a selective MC1R agonist FDA-approved for erythropoietic protoporphyria. Melanotan II is non-selective, affecting tanning, sexual function, and appetite.

References

  1. Wessells H et al. "Melanotan II: a review of the clinical and experimental findings".” International Journal of Impotence Research (2000). PMID: 10893508

📚 Related Articles

Looking for a trusted source? See our recommended suppliers →

Independently tested · COA-verified · Save 10% with our exclusive code