Melanotan II

Melanotan II is a synthetic, cyclic peptide and an agonist at several melanocortin receptors. It is a different type from the weight-loss peptides: instead of metabolism, it acts on the melanocortin pathways, which among other things control skin pigmentation, libido and appetite.

In a research context it is mainly linked to two effects: stronger skin tanning and an effect on sexual function. It is used subcutaneously, dosed in micrograms, as a freeze-dried powder you dissolve in bacteriostatic water.

Melanotan II engages several melanocortin receptors at once. Via the MC1 receptor it prompts the skin's melanocytes to produce more melanin, which in a research context is described as stronger tanning, even with less UV. Via the MC4 receptor in the brain it is linked to libido and erection as well as to appetite suppression.

Important: stronger tanning does not mean the skin is protected from UV damage. UV protection does not rise to the same degree as the pigmentation.

Melanotan II is used subcutaneously. You need:

The powder is dissolved in bacteriostatic water. How much water you add sets the concentration and therefore how many units you draw for your dose on the insulin syringe.

Use the peptide calculator for this: pick the water volume to see the concentration and units per dose. Because Melanotan II is dosed in small microgram amounts, a not-too-high concentration is practical so the units stay easy to read.

When dissolving, just add the bac water, it does not matter if it hits the powder directly. Then swirl or shake until everything has dissolved, both are fine.

The injection is subcutaneous, into the fat layer under the skin, classically the abdomen (keep about two finger-widths clear of the navel), the front and the inner side of the thigh or the back of the upper arm.

Rotate the site each time.

The evidence on Melanotan II is small and old. That deserves to be said. In a phase I study (Dorr, 1996) it led to visibly stronger pigmentation in the subjects. In studies from the late 1990s and early 2000s (Wessells), the melanocortin agonist was linked to erection and sexual motivation. Large, modern safety studies are missing. There is no approved product either. Meaning: the effects are described, but the data base is thin.

The studies with links are in the source block below.

Melanotan II has a more noticeable side-effect profile than most other peptides here, so honestly and clearly:

• Nausea, mainly in the early phase and after each dose. Starting low helps the most.
• Facial flush (heat, redness) and occasionally loss of appetite.
• Spontaneous erections, often together with yawning and stretching.
• Darkening of moles and freckles. Keep an eye on new or changing pigmented spots and, when in doubt, have them checked by a dermatologist. This is the most important safety point.

Never too much at once. Single case reports with untested products describe serious courses:

• Melanoma in a 20-year-old after injections plus tanning beds (Hjuler 2014)
• Toxicity with muscle breakdown (rhabdomyolysis) and worse kidney values after a man injected six times his starting amount at once (Nelson 2012)
• Painful persistent erection (priapism) that needed surgery (Mallory 2021). An erection that does not subside is an emergency.
• Kidney infarction, most likely caused by Melanotan II (Peters 2020)

A few things that matter:

The undissolved powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. The reconstituted solution goes into the fridge (2 to 8 degrees) and stays stable there for at least 4 to 6 months with barely any loss of potency, in practice considerably longer. The bacteriostatic water brings a preservative that keeps the dissolved form stable for longer.