What Is Melanotan I? Dosage, Half-Life & How to Track It

What Melanotan I is and how it works

Melanotan I is a synthetic peptide analog of alpha-melanocyte-stimulating hormone (α-MSH), the natural hormone that activates melanocortin receptors on skin pigment cells (melanocytes) to ramp up melanin production — the pigment responsible for tanning. It was developed by the same University of Arizona research program that produced Melanotan II, aiming to isolate the tanning effect from other melanocortin-driven effects like appetite and libido.

The distinction from its better-known sibling, Melanotan II, is not primarily about receptor selectivity — like MT-2, Melanotan I is a non-selective melanocortin agonist, activating the MC1, MC3, MC4, and MC5 receptors rather than binding narrowly to the MC1 receptor most responsible for pigmentation. Its milder side-effect profile relative to MT-2 — MT-2 is associated with side effects like appetite suppression and spontaneous erections that MT-1 is not reported to share — is not simply explained by tighter receptor selectivity. Melanotan I is, in fact, the same peptide as afamelanotide, FDA-approved under the brand name Scenesse — a slow-release implant of that identical peptide, not a separate compound — for erythropoietic protoporphyria, a rare condition causing severe light sensitivity, a real regulatory pathway that MT-1 sold as a research peptide has not gone through.

Worth being precise about the evidence: afamelanotide's approval means the melanocortin-tanning mechanism itself is clinically validated, but research-grade MT-1 sold outside that approved formulation and indication has not been through the same trials, and is not FDA-approved for cosmetic tanning use.

Typical dosing & reconstitution

Melanotan I ships as a lyophilized powder reconstituted with bacteriostatic water. Community protocols typically use a loading phase of about 0.1–0.3 mg subcutaneously once daily for the first 1–2 weeks to build initial pigmentation, then step down to a maintenance dose (often every other day or a few times a week) to sustain the tan with continued modest sun exposure.

Reconstitution options set concentration and units:

At 5 mg/mL, a 200 mcg loading dose is 4 units on a U-100 insulin syringe. The reconstitution calculator handles the concentration math for any vial and water amount actually on hand.

Half-life & what it means for frequency

Research-grade Melanotan I clears relatively quickly from the blood, with estimates in the range of 30–50 minutes — short enough that the once-daily loading schedule is about sustaining a repeated pigmentation signal, not maintaining a constant blood level. That is broadly consistent with other short synthetic peptides in this library, though MT-1-specific human PK data is limited compared to the FDA-reviewed afamelanotide formulation.

The maintenance phase (spacing doses out once a tan is established) works because melanin production, once triggered, persists in the skin independent of continued receptor stimulation — you are not chasing a blood level, you are maintaining a pigmentation state that decays slowly on its own.

What to track & common side effects

Reported side effects are generally milder than Melanotan II's — the most common are injection-site irritation, mild nausea (especially early in loading), and flushing. MT-1 is not more MC1-selective than MT-2, but users generally do not report the appetite suppression or spontaneous erections associated with MT-2 to the same degree, though individual response varies and the reason for the difference is not fully established.

As with any melanocortin agonist, the most important thing to track over time is skin changes — new or changing moles are worth photographing and monitoring, since melanocyte stimulation is systemic, not confined to sun-exposed areas. Logging the loading-vs-maintenance dose and UV exposure alongside it also helps separate the peptide's effect from ordinary sun tanning.

Frequently asked questions