Melanotan II: Everything You Need to Know

What Is Melanotan II?

Melanotan II (MT-II) is a synthetic analog of alpha-melanocyte-stimulating hormone (alpha-MSH), a naturally occurring peptide that regulates skin pigmentation. Developed at the University of Arizona in the 1990s, MT-II was originally researched as a potential treatment for skin conditions and as a protective agent against UV-induced skin damage.

MT-II is a cyclic heptapeptide (7 amino acids) that binds to multiple melanocortin receptor subtypes, particularly MC1R (pigmentation), MC3R (energy homeostasis), MC4R (sexual function and appetite), and MC5R (sebaceous gland function). This broad receptor activity explains its diverse effects beyond tanning.

How Melanotan II Works

The tanning mechanism involves binding to MC1R on melanocytes in the skin. This triggers a signaling cascade that increases production of eumelanin, the brown-black pigment responsible for darker skin tones. The process mirrors what happens naturally with UV exposure, but MT-II accelerates and amplifies it.

Importantly, MT-II does not require UV exposure to increase melanin production, though combining it with moderate UV exposure produces faster and more even results. The peptide essentially primes the melanocytes to produce pigment, and UV light activates those primed cells.

Dosing Protocol

Loading Phase (Weeks 1-3)

• Starting dose: 100-250 mcg per day (start low to assess tolerance)
• Target loading dose: 250-500 mcg per day
• Duration: 2-3 weeks or until desired pigmentation level is reached
• Injection route: Subcutaneous, typically in the abdomen

Maintenance Phase

• Dose: 250-500 mcg, 1-2 times per week
• Frequency depends on UV exposure and individual melanin retention
• Some individuals maintain pigmentation with as little as one injection per week

Peptide Calculator Settings for MT-II

MT-II typically comes in 10 mg vials. Using the Peptide Calculator Plus:

• 10 mg vial reconstituted with 2 mL BAC water = 5,000 mcg/mL
• For a 250 mcg dose: draw 5 units on a U-100 syringe
• For a 500 mcg dose: draw 10 units on a U-100 syringe

Side Effects and Management

MT-II's side effects are well-documented and generally manageable:

• Nausea -- The most common side effect, affecting most users during initial doses. Starting with a low dose (100-150 mcg) and increasing gradually minimizes this. Some users take the injection before bed to sleep through the nausea.
• Facial flushing -- Temporary redness of the face lasting 30-60 minutes after injection. Harmless but noticeable.
• Mole darkening -- Existing moles and freckles may darken. Monitor moles for changes in shape, size, or border irregularity. Consult a dermatologist if concerning changes occur.
• Increased libido -- MT-II's activity on MC4R receptors produces a noticeable increase in sexual arousal in many users. This effect is dose-dependent and is the basis for the related peptide PT-141 (Bremelanotide).
• Appetite suppression -- MC3R and MC4R activation can reduce appetite in some users.
• Fatigue -- Some users report feeling tired for 1-2 hours after injection, particularly during the loading phase.

Safety Considerations

The primary safety concern with MT-II relates to mole changes and the theoretical risk of melanoma promotion. While MT-II has not been shown to cause melanoma in studies, it stimulates melanocyte activity, and there is a theoretical risk that it could promote growth of pre-existing melanocytic lesions. Individuals with a history of melanoma, dysplastic nevi, or a family history of melanoma should exercise extreme caution.

Regular skin checks by a dermatologist are recommended for anyone using melanotropic peptides.

MT-II vs MT-I (Afamelanotide)

Melanotan I (afamelanotide) is a linear peptide that selectively targets MC1R. It has been approved in Europe as Scenesse for the treatment of erythropoietic protoporphyria (EPP), a condition causing severe light sensitivity. MT-I produces tanning effects with fewer non-pigmentation side effects compared to MT-II, as it does not significantly activate MC3R, MC4R, or MC5R. However, MT-II remains more widely available in the research peptide market.

Storage and Handling

Lyophilized MT-II should be stored in the freezer (-20C) for long-term storage or the refrigerator (2-8C) for short-term use. Once reconstituted with bacteriostatic water, the solution must be refrigerated and used within 4-6 weeks. Protect from light at all times, as UV exposure can degrade the peptide in solution.