Melanotan II
Synthetic analogue of alpha-MSH, an agonist of melanocortin receptors
In volunteers, Melanotan II increased skin pigmentation measurably within a few days, with minimal sun exposure (Dorr, Life Sciences, 1996).
It is a cyclic analogue of alpha-MSH, the hormone that drives melanin production: it resists breakdown and activates several of the five melanocortin receptors.
It is also studied for libido: in a placebo-controlled trial, 8 men out of 10 had an erection (Wessells, 1998). It was developed at the University of Arizona in the 1990s.
- Half-life
- Longer than the natural hormone thanks to its cyclic structure; the effect on pigmentation builds up and persists for weeks.
- Route
- Subcutaneous injection.
Technical sheet
- Family
- Synthetic analogue of alpha-MSH, an agonist of melanocortin receptors
- Half-life
- Longer than the natural hormone thanks to its cyclic structure; the effect on pigmentation builds up and persists for weeks.
- Route
- Subcutaneous injection.
- Time to effect
- Progressive tanning over two to four weeks, faster with moderate sun exposure; effect on libido within the hours that follow.
- Level of evidence
- Documented in humans
Melanotan II amplifies the skin's response to light: sun exposure still needs to be measured carefully, and sun protection remains essential.
Chemical identity
- Form
- Synthetic peptide, values for the base form
- CAS No.
- 121062-08-6
Salt form: as stated on the lot's certificate of analysis.
Melanocortin: a system with several receptors
Alpha-MSH acts on five melanocortin receptors (MC1R through MC5R), in the skin, the brain, and the immune system. Melanotan II, a cyclic, shortened analogue of the hormone, resists breakdown, activates several of them at once, and acts much longer than the natural hormone.
MC1R: melanin
In the skin, the MC1R receptor on melanocytes triggers the production of eumelanin, the dark pigment: the complexion darkens gradually, more evenly than with sun exposure alone. A darker complexion does not protect you from UV rays: sunscreen is still needed, and so is watching your moles.
MC3R and MC4R: desire and appetite
In the hypothalamus, the MC3R and MC4R receptors take part in controlling appetite and sexual response: hence the effect on libido, discovered during the earliest trials, and the reduced appetite often reported.
Effects and realistic timelines
Fast tan: measurable pigmentation within a few days, with little sun
Two to four weeks
Sexual desire: an erection in 8 men out of 10 in a placebo-controlled trial
Hours
Appetite: it activates MC4R, a hypothalamic receptor that regulates appetite
Days
What you may feel
- Nausea and flushing within the hour that follows, especially at the start.
- Darkening of existing moles and spots; appearance of new moles.
- Spontaneous or prolonged erections in men.
- Temporary fatigue or drowsiness.
Stop and consult if
- A mole that changes shape, colour, or border: have it examined without delay.
- An erection that lasts more than four hours.
- Persistent nausea, vomiting.
When to abstain
- A personal or family history of melanoma, or numerous atypical moles.
- Pregnancy or breastfeeding.
- Uncontrolled hypertension or cardiovascular disease.
- Minors.
The effects to watch for, and how to reduce them
This sheet is educational. It replaces neither a diagnosis nor follow-up: for any medical condition, pregnancy, breastfeeding or current medication, talk to a health professional.
- PT-141Its specialized derivative for sexual response, without the tanning effect; you choose one or the other, never both on the same day.
- GHK-CuTwo peptides studied for the skin through two separate pathways: Melanotan II for pigmentation, GHK-Cu for collagen and elastin.
To avoid
- Intense sun exposure without protection: the peptide amplifies the skin's response, it doesn't replace sunscreen.
- PT-141 on the same day: same receptors, nausea and blood pressure increases that add up.
Melanotan II has been studied in humans since the 1990s: pigmentation in volunteers, then erectile function, with an effect measured against placebo. This work established the mechanism and tolerability, and paved the way for bremelanotide (PT-141).
1996 · Dorr et al., Life Sciences
Healthy human volunteers, subcutaneous Melanotan II
Measurable increase in skin pigmentation after a few days, with minimal sun exposure; transient side effects (nausea, fatigue) and spontaneous erections were reported.
1998 · Wessells et al., Journal of Urology
Double-blind, placebo-controlled trial in men with erectile dysfunction
Erections achieved in a large majority of participants on Melanotan II, with increased desire reported: the demonstration of a central effect on sexual response.
2000 · Wessells et al., International Journal of Impotence Research
Controlled trial in men with erectile dysfunction of psychogenic origin
Confirmation of the effect on erection and desire, independent of direct stimulation, via central melanocortin receptors.
Does it tan without sun?
It needs little sun: moderate exposure speeds up and evens out the result, and with no light at all the effect comes more slowly and more lightly. Sun protection is still necessary: a darker complexion isn't a full sunblock.
Why keep an eye on your moles?
Because the peptide stimulates all melanocytes, including those in moles, which darken. Any mole that changes in shape, colour, or border should be examined; a skin check before starting is a good habit.
Why does appetite drop?
It activates MC4R, a hypothalamic receptor involved in controlling appetite and sexual response: hence the reduced appetite often reported, alongside the effect on desire.
Glossary (5)
- Alpha-MSH
- A melanotropic hormone that controls pigmentation and also acts on appetite and desire.
- Melanocyte
- A skin cell that manufactures melanin.
- Eumelanin
- The brown-black pigment of skin and hair, protective against UV rays.
- Melanocortin receptors (MC1R through MC5R)
- A family of alpha-MSH receptors, found in the skin, the brain, and immune cells.
- Cyclic peptide
- A peptide whose chain is closed back on itself, which makes it more stable.