Melanotan II
Melanotan II (MT-II)
Also called Melanotan II, MT-2, MT-II, the Barbie drug
Tanning and libido through the melanocortin system
Melanotan-2 makes your skin produce pigment without sunlight, which is why it got the nickname. It also, as a side effect nobody planned, causes erections, which is how the erectile dysfunction drug PT-141 came to exist. It is unregulated, widely used, and the compound in this catalogue whose side effects people most consistently underestimate.
A synthetic analog of alpha-MSH that activates the melanocortin receptors, driving skin pigmentation (tanning) through MC1R and sexual arousal and appetite suppression through MC4R. Its dual action — and a tendency to cause nausea and existing-mole darkening — makes individual response highly genotype-dependent.
- Half-life
- ~33 hours
- Route
- Subcutaneous injection
- Typical dose
- 0.25–0.5 mg (titrate up)
- Availability
- Research-only
Studied in people, and well studied in animals
What people use Melanotan II for
Reported uses, roughly in order of how often they are the reason someone goes looking. Whether it works for any of them is a separate question, answered under each one.
- Tanning without the sun
- The main reason people use it. It switches on the same pigment machinery UV does, so you darken without the burning. People with fair skin who do not tan easily are the usual users.
- Libido and erections
- The accidental discovery. The effect was strong enough in early trials that researchers built a separate drug around it, which became PT-141.
- Appetite suppression
- A third effect people notice rather than seek. The same receptor family is involved in appetite, and reduced hunger is commonly reported.
Mechanism of Action
How Melanotan II works
Melanotan II is a broad melanocortin-receptor agonist:
- MC1R activation (pigmentation) — stimulates melanocytes to produce eumelanin, increasing tanning with less UV exposure. The strength of this response is tightly tied to your MC1R genotype.
- MC4R activation (libido & appetite) — engages central MC4R pathways that increase sexual arousal and suppress appetite, the basis for its libido and mild weight effects.
- Non-selectivity — because it hits multiple melanocortin receptors, it commonly causes nausea, flushing and darkening of existing moles and freckles.
- Central nervous action — the arousal effect is centrally mediated, distinct from blood-flow agents, and overlaps mechanistically with PT-141 (a related melanocortin peptide).
Melanotan II dosage calculator
Opens at 0.25 mg, from the doses reported for Melanotan II. Change any box to match your own vial. It works out where to pull the plunger to.
How much is in the vial?
Printed on the label, in milligrams
How much water did you add?
Bacteriostatic water, in millilitres
What dose are you taking?
The dose you already intend to use
Which syringe?
Barrel size, printed on the wrapper
Draw to
5 units
on a 0.5 mL insulin syringe (0.05 mL)
- Strength once mixed
- 5 mg/mL
- Doses in the vial
- 40
10 mg in 2 mL makes 5 mg/mL. A 0.25 mg dose is 0.05 mL of that, which is 5 units.
Want a rounder number? Adding 4 mL instead would put this dose at exactly 10 units, which is easier to draw accurately.
This is arithmetic, not advice. It converts a dose you already have into a mark on a syringe. It does not tell you what dose to take, and Melanotan II is not prescribed by us. Dosing belongs with a qualified clinician.
Melanotan II side effects: what people reported
This one has a lot, they are common rather than rare, and the first dose is usually a memorable experience. Most people who describe the compound fondly are describing it after they lowered the dose.
What most people notice
- Nausea, often within an hour of the first doses and strong enough to be memorable
- Facial flushing
- Spontaneous erections, including at unhelpful moments
- Reduced appetite
- Tiredness or a heavy feeling after a dose
Worth keeping an eye on
- Existing moles and freckles getting darker, and new ones appearing. This is extremely commonly reported
- Uneven pigmentation, including patches that darken more than the rest
- Darkening that persists long after stopping
The one that matters
- Because it changes moles, it can mask or mimic the changes dermatologists look for when checking for skin cancer. Anyone using it should be getting skin checks and telling the doctor they are using it, which people rarely do
- Case reports exist of melanoma diagnosed in users. Cause is not established, but the effect on moles is a genuine complicating factor
Dose matters. Nausea and flushing track the dose closely and are worst in the first few days. Most protocols start at a fraction of a full dose for this reason.
Source: Reported use and early trial work; there is no approved product to draw formal data from. This is a summary of published findings, not a complete safety profile and not medical advice. Melanotan II should only be considered with a qualified clinician who knows your history.
Your Genetics & Melanotan II
The genes involved in how Melanotan II works
Melanotan II works through the receptors these genes build, and the genes vary from person to person. Researchers have linked some of that variation to differences in how people respond. A DNA report tells you which versions you carry.
MC1R · ••
The R151C red-hair-associated variant reduces MC1R signaling toward eumelanin. Carriers (often fair-skinned, red-haired) tan poorly even with Melanotan II, since the receptor it targets for pigmentation signals weakly.
MC4R · ••
Variants near MC4R alter central melanocortin signaling. This influences how strongly Melanotan II drives the libido and appetite-suppression effects, which run through MC4R rather than MC1R.
OCA2 is central to melanin production. Variants here shape baseline pigmentation capacity and therefore how visible a tanning response is once MC1R is stimulated.
COMT · ••
The Val158Met variant changes how quickly catecholamines are cleared, which can modulate the nausea and flushing many users experience with melanocortin agonists like Melanotan II.
The dots after each gene are where your own result goes. Your report fills them in with the two letters you carry at that position.
Which variants do you carry?
Upload your DNA data, or get tested through our partner, to find out.
Commonly combined with
What Melanotan II is most often paired with, and why:
PT-141
Sexual Health StackStrong EvidencePT-141 (Bremelanotide)
An injection taken before sex, approved as Vyleesi for low sexual desire in premenopausal women. Viagra and its relatives work on blood flow; this works on wanting, acting on the part of the brain that sets drives like hunger and arousal. That is why it can help where the plumbing was never the problem.
Sourcing & access
Where to buy Melanotan II
Melanotan II is sold as a research compound, not a licensed medicine, so quality and legal status vary widely by country and vendor. If you're sourcing it, treat independent purity testing as non-negotiable.
- Insist on a recent third-party Certificate of Analysis (COA) for the exact batch — labs like Janoshik verify purity and identity.
- Check the legal status where you live before ordering — it differs from country to country.
- Reconstitute correctly with bacteriostatic water and start at a conservative dose.
Melanotan II
Tanning and libido through the melanocortin system
$27.96at Swiss Chems
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Before you buy: see whether your DNA actually responds to Melanotan II, and at what dose. Analyze my DNA — $99 →
Educational information only, not medical advice. Some outbound links are affiliate links (disclosed, at no extra cost to you). Most peptides are not FDA-approved — consult a qualified professional and check your local laws before purchasing.
Worth knowing before you consider Melanotan II
Interactions and situations where there is a specific reason to be careful. Where the honest answer is that nobody has studied something, it says so and says what that leaves open.
- Tell your doctor if you get a mole checked
- The single most useful thing on this page. A mole that has changed is the main warning sign for skin cancer, and this compound changes moles. A dermatologist who does not know that is working with bad information.
- Start far lower than you think
- Almost every horror story about the first dose is a dosing story. People who ease into it describe a very different experience from people who do not.
- It does not protect you from burning
- Pigment is not sunscreen. People assume a tan means they can stay out longer, which is how they end up burnt anyway.
Last updated
Frequently Asked Questions
Why do some people barely tan on Melanotan II?
Tanning runs through MC1R, the melanocortin-1 receptor. People carrying loss-of-signal MC1R variants (commonly fair-skinned or red-haired individuals) have a receptor that signals weakly toward pigment, so even with Melanotan II the tanning response is muted. Your MC1R genotype is the main predictor.
How is Melanotan II related to PT-141?
PT-141 (bremelanotide) is a closely related melanocortin peptide derived from the same family. Both act centrally on melanocortin receptors for arousal, but PT-141 is more selective for the sexual-arousal pathway, while Melanotan II also drives pigmentation through MC1R.
Does genetics affect Melanotan II response?
Yes, strongly. MC1R variants determine the tanning response, MC4R variants shape libido and appetite effects, OCA2 sets baseline pigment capacity, and COMT influences nausea and flushing. A genetic peptide report profiles these so you know what to expect before starting.
Learn more about Melanotan II
Your next move
Two ways forward with Melanotan II.
Not sure it's for you?
How does Melanotan II relate to your genes?
Your report scores Melanotan II against your receptor, pharmacogene and pathway variants and shows the genetic markers relevant to it, with commonly cited dosing information to review with a clinician.
Analyze my DNA — $99Already decided?
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