Peptide education
Melanotan-2
Melanotan II · MT-2 · MT-II · MII
Melanotan-2 is a synthetic ring-shaped relative of the tanning hormone alpha-MSH that never became a medicine. It activates several melanocortin receptors at once, which is why a single gray-market vial gets sold for tanning, libido, and appetite suppression at the same time. Small, older human studies did find real pigmentation and real erectile effects, so the biology behind the reputation is not imaginary. What is imaginary is the product: no approved version appears anywhere in the cited sources, and published testing of internet vials found contents that did not match their labels.
The peptide itself does roughly what its reputation says, at least in small old studies: it darkens skin and it can produce erections. The problem is everything after that: no approved product, warnings from the FDA, TGA, and Health Canada, and internet vials that tested well short of their labeled 10 mg with unknown impurities mixed in.
Overview
Quick answer
Melanotan-2 is not afamelanotide, Melanotan-1, Scenesse, PT-141, or Vyleesi. Afamelanotide is the regulated Scenesse implant for erythropoietic protoporphyria, and bremelanotide is the regulated Vyleesi injection for a narrow HSDD indication. Those products show that the melanocortin pathway can support regulated drugs, but they cannot tell you whether a gray-market Melanotan-2 vial or nasal product contains the right compound, is sterile, is accurately dosed, or is safe for tanning use.
What is Melanotan-2?
A synthetic cyclic heptapeptide: seven amino acids in a ring, built from alpha-MSH, that agonizes melanocortin receptors MC1R, MC3R, and MC4R. That receptor spread is the compound's whole personality: MC1R gives the tanning, MC4R gives the libido and appetite effects, and the lack of selectivity gives the nausea, yawning, and flushing.
What do people use it for?
Mostly tanning: a pre-holiday or pre-competition tan, often alongside sunbeds, with libido and erection effects treated as a bonus or a nuisance and appetite suppression claimed around the edges. The published human basis for all of this is a handful of small old studies showing pigmentation and erectile effects. Weight-loss claims have no comparable human data behind them.
What route and exposure patterns are reported?
The studies used monitored subcutaneous dosing, down to 0.025 mg/kg in the erectile-function work. The market speaks a different language: community protocols describe roughly 250 to 500 mcg a day during a 2 to 4 week loading phase, then 500 mcg to 1 mg once or twice weekly, plus nasal sprays with per-spray claims nobody verifies. Study dosing was monitored research; community schedules are reported practice, not validated regimens.
What is the product-level bottom line?
Assume the vial is the weakest link. When researchers bought and tested internet MT-II, products labeled 10 mg contained about 4.32 to 8.84 mg, with unknown impurities around 4.1% to 5.9% in some samples. A compound this biologically active deserves better dose math than that.
Reported practice
Commonly reported protocol
Injectable loading-and-maintenance protocols. Community-reported patterns, not verified by controlled human trials and not a use recommendation. Full use-pattern detail
Evidence
Evidence snapshot
Small human studies found pigmentation and male erectile-function findings. They show the compound can act biologically, but they do not define a safe tanning product, a wellness use, or a dependable use pattern.
FDA enforcement material treated injectable Melanotan II marketing as unapproved new-drug promotion, and regulator warnings in other countries describe melanotan products as unauthorized or illegally promoted online.
The available warnings line up with concerns about product identity, concentration, labeling, contamination, storage, and manufacturing. Published testing found internet-sold vials labeled 10 mg that contained about 4.32 to 8.84 mg MT-II, with unknown impurities around 4.1% to 5.9% in some samples.
Afamelanotide and bremelanotide are separate approved melanocortin products with their own indications and labels. They help explain the pathway, not the safety or legality of MT-II products.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Anecdotal evidence | Verdict |
|---|---|---|---|---|
| It darkens skin or increases tanning. | Early human pigmentation findings appeared after subcutaneous exposure. That shows a narrow biologic finding, not an approved cosmetic indication or a reliable tanning regimen. | Melanocortin signaling through pigmentation biology gives the claim a plausible mechanism, especially through MC1R-related melanogenesis. | Online tanning discussion commonly describes injectable powders, nasal sprays, pre-holiday use, sunbed co-use, and physique-focused use, but those reports cannot show safety or dose reliability. | There is a real pigmentation finding, but the evidence is too limited and the market too unreliable to treat MT-II as a safe tanning product. |
| It boosts libido or erections. | Small older placebo-controlled male ED studies found erection and sexual-desire findings after monitored subcutaneous dosing. | The melanocortin pathway is plausibly involved in sexual function, and bremelanotide's separate label shows that this drug family can have approved sexual-function use in a different molecule and population. | Forum and gray-market discussion often attaches libido or erection expectations to MT-II, sometimes as an unwanted effect and sometimes as the intended effect. | The finding is credible enough to mention, but the evidence does not make gray-market MT-II a general libido or sexual-performance product. |
| It helps appetite control or weight loss. | Small ED-study safety observations included decreased appetite, but convincing MT-II human weight-loss evidence was not found. | MC3R and MC4R biology connects melanocortin signaling to energy homeostasis, so appetite discussion is biologically plausible. | Online use sometimes mentions appetite suppression or physique goals, usually mixed with tanning and bodybuilding contexts rather than controlled weight-loss data. | Appetite effects can be discussed as a possible melanocortin effect, but reliable MT-II weight-loss efficacy has not been shown. |
| It replaces sunscreen or protects against skin cancer. | MT-II has not been shown to work as a sunscreen replacement or skin-cancer-prevention product. | More pigment can change appearance, but tested UV protection and skin-cancer prevention are different claims from darker skin. | Tanning-product marketing and forum discussion can imply safer tanning, but regulators warn against treating melanotan products as protective. | No. TGA specifically warns against relying on melanotan products instead of sun protection, and FDA enforcement material treated skin-cancer and rosacea claims as unlawful promotion. |
| A vendor COA makes the vial safe. | A vendor document may describe a test result, but it leaves the practical safety questions open: finished-vial sterility, endotoxin control, correct concentration, clinical outcomes, and whether the shipped lot matches the document. | This is a manufacturing and supply-chain problem, not a receptor-biology problem. | Gray-market listings may present purity, COA, or research-use language while still leaving the buyer with no regulated finished-drug assurance. | A COA is a narrow sample document. For MT-II, product identity and finished-product controls matter as much as the pharmacology. |
Bottom line
Main takeaway
Melanotan-2 is the unapproved tanning injection regulators keep warning about. The effects people describe are plausible enough, and the products being sold are still unverified, mislabeled, or both.
Do not let the melanocortin family blur the comparison. Scenesse and Vyleesi prove this pathway can support regulated drugs; neither one says anything about what is in an MT-II vial or whether a nasal spray delivers a known dose.
The useful anchors are the review-summarized early human studies for the pigmentation and ED signals, the FDA, TGA, and Health Canada materials for market reality, and the approved Scenesse and Vyleesi labels as contrast. Together they describe the compound better than any vendor page.
Identity
What it is
Melanotan-2 is a synthetic cyclic heptapeptide analog of alpha-MSH: the natural tanning hormone rebuilt as a small ring-shaped molecule. PubChem lists it as melanotan-II, sequence Ac-Nle-Asp(1)-His-D-Phe-Arg-Trp-Lys(1)-NH2.
The ring changed the pharmacology. Where its linear cousin Melanotan-1 leans toward the pigment receptor MC1R, MT-II hits MC1R, MC3R, and MC4R together, so one molecule produces a tan, sexual effects, appetite changes, and the nausea-yawning-flushing cluster users report. The same research lineage eventually refined the sexual branch into bremelanotide, the drug now approved as Vyleesi.
The human data are real and thin. Review literature summarizes an early study in which three men tanned after five low every-other-day subcutaneous doses, plus small placebo-controlled crossover studies in which 0.025 mg/kg produced clinically apparent erections inside a six-hour window, with nausea and yawning prominent. That is enough to call the compound biologically active and nowhere near enough to call it a safe tanning product.
Everything past that is a market story. No approved MT-II product appears in the cited sources; FDA enforcement treated injectable Melanotan II marketing as unapproved new-drug promotion, and Australian and Canadian regulators warn against melanotan products outright. The vials and sprays people actually buy have been lab-tested and found short of their labels, which is the detail that should anchor every conversation about this compound.
How people talk about it online
MT-II threads read like vacation prep crossed with side-effect management: loading schedules timed to holidays or physique shows, sunbed co-use, appetite suppression as a bonus, and long arguments about whether darkening moles are part of the look or a reason to see a dermatologist. The mole changes are the detail that matters most and gets treated most casually.
Route talk is confident and unsupported. Injectable powders, nasal sprays, and drops get discussed as simple preferences, but the human studies used monitored subcutaneous dosing, per-spray peptide delivery is imprecise by design, and regulators have flagged nasal spray formats specifically.
Vendor pages lean on purity percentages and COAs. Keep in mind what published testing actually found in this market: vials labeled 10 mg testing at 4.32 to 8.84 mg, with unidentified impurities alongside. A certificate that cannot guarantee the amount in the vial is not a safety document.
Use context
Routes, doses, and cycle patterns
MT-II use information splits into two very different categories. The study material used monitored subcutaneous mg/kg exposure in very small human studies. The real-world material describes unapproved injectable powders, nasal products, vendor listings, and forum use. Public discussions mention loading and maintenance, but none of that establishes a dependable tanning schedule.
Human studies and product labels
No FDA-approved Melanotan-2 label
- Purpose
- Approval-status check
- Context
- FDA enforcement and regulator warnings
- Route
- No FDA-approved MT-II route
- Amount
- No FDA-approved MT-II amount
- Frequency
- No FDA-approved MT-II frequency
- Duration
- No FDA-approved MT-II duration
FDA enforcement material treated Melanotan II marketed as an injectable tanning product as an unapproved new drug. TGA and Health Canada warnings likewise describe unauthorized or illegally promoted melanotan products.
Early pigmentation exposure in historical human study
- Purpose
- Human tanning and pigmentation signal
- Context
- Small early human study summarized in review literature
- Route
- Subcutaneous
- Amount
- Low-dose subcutaneous exposure in a monitored study setting
- Frequency
- Every other day in the early low-dose study setting
- Duration
- Tanning activity described after five low doses
Pigmentation effects were observed in humans. The dose details belong to historical monitored research, not an approved cosmetic regimen or an answer to long-term skin or product risk.
Male ED monitored crossover exposure in historical study
- Purpose
- Erection signal in men with psychogenic ED
- Context
- Small placebo-controlled human crossover study summarized in review literature
- Route
- Subcutaneous
- Amount
- 0.025 mg/kg in a monitored study setting
- Frequency
- Single monitored exposure versus placebo
- Duration
- Six-hour monitoring window
Review literature describes clinically apparent erections after MT-II, along with nausea, yawning, stretching, and decreased appetite. The study shows a finding, not a general sexual-performance regimen.
Male ED repeated crossover exposure in historical study
- Purpose
- Erection and sexual-desire signal in men with organic and psychogenic ED
- Context
- Small placebo-controlled human crossover study summarized in review literature
- Route
- Subcutaneous
- Amount
- 0.025 mg/kg in a monitored study setting
- Frequency
- MT-II and vehicle were each administered twice under crossover conditions
- Duration
- Six-hour monitoring windows
More subjectively reported erections and higher sexual-desire scores were described after MT-II than after placebo, with nausea and yawning remaining prominent adverse effects. This remains early monitored research, not a basis for gray-market libido or performance use.
Real-world discussion
Injectable loading-and-maintenance protocols
- Purpose
- Tanning, with libido and appetite discussion
- Context
- Forums, vendors, and protocol blogs
- Route
- Subcutaneous injection
- Amount
- Usually described around 250 to 500 mcg per day during loading, then 500 mcg to 1 mg once or twice weekly as maintenance. Community sources often suggest starting at the low end because nausea and flushing are dose-related.
- Frequency
- Daily while loading, then weekly in most descriptions
- Duration
- Loading commonly described as 2 to 4 weeks, maintenance open-ended
The loading-then-maintenance pattern is the stable community convention for MT-2. Nausea, facial flushing, and darkening of existing moles are the most consistently reported effects, and the mole changes are the reason dermatology voices object. These are reported patterns, not recommendations.
Nasal sprays and nonstandard formats
- Purpose
- Tanning without injection
- Context
- Vendor listings and regulator material
- Route
- Intranasal sprays and drops
- Amount
- Spray products are marketed with per-spray mcg claims that vary widely and are not independently verified
- Frequency
- Daily use is commonly marketed
- Duration
- Marketed as ongoing
Regulators have flagged nasal spray formats specifically; per-spray delivery of a peptide is inherently imprecise, and these products sit outside any quality framework. These are reported patterns, not recommendations.
What varies
- Goal: tanning, sexual-function, and appetite claims have different evidence strength and different safety questions.
- Route: subcutaneous studies tell you the monitored research route; nasal sprays, drops, oral products, and vendor route claims still require absorption, dosing, and safety evidence.
- Amount: mg/kg study exposure cannot be read straight across to multi-milligram vials when the actual vial content and dilution math may be wrong.
- Frequency: every-other-day study exposure and monitored ED doses do not define a tanning-season loading, maintenance, or cycling plan.
- Product quality: identity, concentration, sterility, endotoxin, storage, shipping, reconstitution, and dose math can change the actual exposure.
- Skin monitoring: darker pigmentation, changing moles, new lesions, sun exposure, and sunbed use all complicate interpretation.
Human data
Human evidence
The human evidence for MT-II is old, small, and real. An early study in three volunteers reported tanning after five low every-other-day subcutaneous doses, and two small placebo-controlled crossover trials in men with erectile dysfunction found more erections and higher desire scores after 0.025 mg/kg, with nausea, yawning, stretching, and appetite loss tagging along. That is the entire positive record: concept-level data from monitored research settings, never developed into an approved product. The strongest current human-relevant literature sits on the other side of the ledger: regulator warnings and case-report reviews documenting mislabeled products and cutaneous complications.
Evidence maturity
Melanotan-2's research lineage produced an approved drug for a different molecule; MT-2 itself remains an unapproved market product with accumulating regulator warnings.
The same research family produced the approved afamelanotide implant.
Community loading-and-maintenance schedules without any approved product.
FDA vendor action in 2016 plus later TGA and Health Canada warnings.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| Early human pigmentation finding under monitored subcutaneous exposure | Three healthy male volunteers | Small early human study summarized in review literature | Investigational MT-II, not a marketed tanning product | Human tanning activity was reported after subcutaneous low-dose exposure, including five low doses every other day in early monitored research. | The sample was tiny, the work was early, and the finding is a weak historical human finding. It does not give a cosmetic-use schedule, long-term skin safety, or gray-market product reliability. | Weak human concept evidence |
| Small monitored ED crossover finding | Men with psychogenic erectile dysfunction | Small double-blind placebo-controlled crossover study summarized in review literature | Investigational MT-II under monitoring | Clinically apparent erections were described after 0.025 mg/kg subcutaneous MT-II, with more monitored high-rigidity time than placebo during the observation window. | The study was small, male-only, old, and monitored for hours after dosing. It does not show general libido enhancement or gray-market personal-use safety. | Moderate finding, weak practice evidence |
| Small repeated ED crossover finding | Men with organic and psychogenic erectile dysfunction | Small placebo-controlled crossover study summarized in review literature | Investigational MT-II under monitoring | More subjectively reported erections and higher sexual-desire scores were described after MT-II than after placebo, with nausea and yawning as common adverse effects. | The findings support real biologic activity, not a broad sexual-performance product claim, and they do not address women, healthy people, nasal products, or repeated real-world cycles. | Moderate finding, weak practice evidence |
| Regulator and review evidence for unapproved melanotan products | People exposed to online melanotan products and marketing | Regulator warnings, FDA enforcement material, and peer-reviewed review | Unapproved, unauthorized, or gray-market products | FDA, TGA, Health Canada, and review material warn about unapproved marketing, unauthorized products, cutaneous complications, online promotion, label reliability, and product quality concerns. Published testing adds a concrete quality finding: internet 10 mg vials contained about 4.32 to 8.84 mg MT-II, with unknown impurities around 4.1% to 5.9% in some samples. | This material is better for risk and market interpretation than for efficacy or adverse-event rate estimates. | Strong for warnings |
| Approved comparator labels | Scenesse-labeled EPP patients and Vyleesi-labeled HSDD patients | Approved product labels for different melanocortin drugs | Regulated afamelanotide and bremelanotide products | The labels show that related melanocortin products have specific approved uses, formulations, indications, warnings, and clinical programs. | Comparator labels explain the pathway and naming confusion. They do not settle whether Melanotan-2 vials or sprays contain the stated compound, deliver a known dose, or support tanning claims. | Strong for distinction, not MT-II efficacy |
Cautions
Safety and unknowns
- Nausea is one of the clearest recurring adverse effects in the small human ED studies, along with yawning, stretching, decreased appetite, and severe nausea at higher study exposure.
- Pigmentation changes are the point of many tanning claims, but changing moles, newly appearing lesions, and darker melanocytic lesions can create real dermatology concerns.
- Sexual effects can be unwanted as well as intended. FDA safety materials include erection-related concerns, including priapism in case-report summaries.
- Flushing, blood-pressure changes, sympathomimetic toxidrome reports, posterior reversible encephalopathy syndrome, renal events, rhabdomyolysis, and other case-level concerns make the risk profile more serious than ordinary tanning marketing suggests.
- MT-II has not been shown to make skin-cancer prevention or sunscreen-replacement claims credible. A pigment change is not the same as tested UV protection, and regulator warnings push against that marketing.
- Long-term repeated-cycle safety is not characterized well enough for tanning-season, bodybuilding-season, or repeated maintenance use.
- Nasal sprays, drops, and injectable vials may carry different exposure and contamination risks. Nasal products need their own dose-equivalence and safety evidence.
- Product quality problems can turn every claimed dose into an estimate. Identity, sterility, endotoxin, concentration, impurities, degradation, reconstitution, storage, shipping, counterfeit risk, and lot mismatch all matter.
Product quality
A vial label is only a starting point
Melanotan-2 is usually encountered outside a regulated finished-drug channel, so the product problem is central rather than incidental.
Health Canada warns that unauthorized injectable peptide products may contain too much, too little, or none of the active ingredient, may include contaminants or unlisted ingredients, and may be made, stored, or labeled improperly.
TGA warns against online melanotan products and says they have not been assessed for quality, safety, or effectiveness.
FDA's bulk-substance safety materials support concern about peptide aggregation, impurities, missing safety information, and product controls for compounded or nonapproved peptide substances.
Identity
A product sold as MT-II may not match the label, the lot document, or the route described in a forum post.
Concentration
Even if the molecule is present, the amount in the vial or spray can differ from what the label, calculator, or forum post implies.
Sterility and endotoxin
Injectable or mucosal products need finished-product controls; purity percentages alone do not answer sterility or endotoxin safety.
Impurities and aggregation
Peptide-related impurities, degradation, and aggregation can change both immune risk and exposure.
Nasal versus injectable products
A nasal product is not automatically safer, equivalent, or easier to interpret. Absorption, local exposure, preservatives, and dose consistency are separate questions.
Shipping and storage
Heat, time, handling, reconstitution, and shipping conditions can change what the finished product contains.
COA limits
A posted COA may describe one test or one sample. It still leaves lot-linked finished-product release testing for the vial or spray someone receives.
Mechanism
How it is proposed to work
Melanotan-2 works through the melanocortin receptor system. That helps explain why one compound can be discussed for skin pigmentation, erections or desire, and appetite at the same time.
MC1R biology is tied to melanogenesis and skin-pigment response, which explains the tanning interest and why pigmentary changes need skin monitoring.
MC3R and MC4R biology connects melanocortin signaling to appetite and energy-homeostasis pathways, but that does not convert MT-II into a human weight-loss product.
Central melanocortin signaling is plausibly connected to sexual function. Bremelanotide's separate approved label supports pathway plausibility while also showing why molecule, indication, route, and label cannot be merged.
MT-II's broader receptor activity helps explain why off-target effects such as nausea, yawning, stretching, appetite change, and spontaneous erections can appear alongside pigmentation.
The tanning effect is MC1R-driven cAMP signaling that raises MITF and tyrosinase activity in melanocytes.
FAQ
Common questions
Is Melanotan-2 an approved tanning drug?
No. Regulatory warnings treat Melanotan-2 as an unapproved product-risk topic, not an approved tanning, sunscreen, libido, appetite, or wellness product.
Does evidence for Scenesse or Vyleesi apply to Melanotan-2?
No. Scenesse and Vyleesi are different regulated products with specific indications, formulations, labels, and safety systems. Their evidence does not transfer to Melanotan-2 or gray-market melanotan products.
Why discuss gray-market products at all?
Because regulators and review literature describe product-quality, labeling, contamination, and online-promotion risks. Gray-market MT-II does not provide a product-quality standard or how-to-use guide.
Details
Technical details
Sources
References
- 1.
Other. PubChem Compound Summary for melanotan-II 2026.
Accessed 2026-06-09.
PubChem source for Melanotan II identity as a synthetic cyclic heptapeptide, CID 92432, and biologic line notation.
- 2.
FDA. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks 2026.
Accessed 2026-06-08.
FDA summarizes potential significant safety risks and missing safety information for several nominated peptide bulk substances.
- 3.
FDA. Notice of Opportunity for Hearing (NOOH) Manookian, Edward 8/5/16 2016.
Accessed 2026-06-09.
FDA enforcement source describing Melanotan II as an unapproved new drug marketed as an injectable tanning product; used only for regulatory-risk and claim-boundary framing.
- 4.
Other. Don't risk using tanning products containing melanotan 2025.
Accessed 2026-06-09.
Australian TGA warning source for melanotan I/II tanning products, online promotion, unapproved-product quality risk, adverse-event concerns, and advertising restrictions.
- 6.
PubMed. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review 2017.
doi:10.1111/ijd.13585 PMID:28266027 Accessed 2026-06-09.
Review source for unregulated melanotan I and II use, product-quality concerns, and reported cutaneous complications; used as a safety boundary, not as use guidance.
- 7.
DailyMed. SCENESSE- afamelanotide implant prescribing information 2026.
Accessed 2026-06-09.
Current structured label source for Scenesse indication, MC1 receptor mechanism, warnings, clinical-trial safety summary, and product identity.
- 8.
DailyMed. VYLEESI- bremelanotide injection prescribing information 2025.
Accessed 2026-06-09.
Current structured label source for Vyleesi indication, limitations of use, warnings, clinical studies, mechanism, and product identity.