Melanotan 1 vs Melanotan 2 (2026): Afamelanotide, MT-II, Tanning, Skin Cancer Risk and What Changed in Canada

Comparison · 19 min read · Updated October 2026

Melanotan 1 vs 2 at a glance

The Arizona origin story

In the 1980s, researchers at the University of Arizona, including Mac Hadley, Victor Hruby and Norman Levine, set out to answer a public-health question: could people at high risk of skin cancer be given a tan without UV exposure, potentially protecting them from sun damage? Arizona, with its intense sun and largely fair-skinned population, had very high skin cancer rates.

Natural α-MSH, the hormone that triggers tanning, lasts only minutes in the body. The team made modified versions that resisted breakdown. The first, later called Melanotan I, replaced two amino acids to stabilize the molecule. In a 1991 study in JAMA, injections tanned the skin of fair-skinned volunteers without sun exposure. The second, Melanotan II, was a smaller ring-shaped version that was far more potent. In its first small human study in 1996, it tanned the skin after only a handful of low doses, and volunteers reported spontaneous erections.

Those two observations sent the molecules in opposite directions. Melanotan I was developed by the Australian company Clinuvel into a medicine for light-sensitivity disorders. Melanotan II’s sexual effects led to the development of bremelanotide (PT-141), while Melanotan II itself was left behind as a research compound and a grey-market tanning product.

How tanning works: α-MSH and MC1R

When UV light damages skin cells, they release α-MSH, which binds the melanocortin 1 receptor (MC1R) on pigment cells called melanocytes. That prompts them to make more eumelanin, the brown-black pigment, and pass it to surrounding skin cells, where it forms a cap over the cell nucleus that absorbs UV.

People with certain MC1R variants, common in those with red hair and fair skin, respond poorly to this signal and make more of the reddish pigment pheomelanin instead. They tan poorly, burn easily and have a higher risk of melanoma. In principle, a drug that activates MC1R directly could produce protective eumelanin without the UV damage that normally triggers it. That was the original promise of the melanotans.

Structure: linear vs cyclic

The two compounds differ in a way that explains almost everything else about them.

• Melanotan I (afamelanotide) is the full 13-amino-acid α-MSH sequence with two changes: norleucine at position 4 and D-phenylalanine at position 7, written as [Nle⁴, D-Phe⁷]-α-MSH. These swaps make it far more resistant to enzymes and more potent at MC1R. The chain stays linear.
• Melanotan II keeps only the core of α-MSH (positions 4 to 10), with similar substitutions, and closes it into a ring through a lactam bridge. Ring-shaped peptides are more rigid, more stable and better able to reach the brain.

That brain penetration is the key difference. MT-I acts mostly on the skin. MT-II acts on the skin and on melanocortin receptors in the brain, which control appetite, sexual function and nausea.

Receptor selectivity: why MT-II does more

When people describe MT-II’s “bonus” effects (reduced appetite, increased libido), they are describing MC4R activation in the brain. They are also describing the source of its most common side effects: nausea, flushing, yawning and stretching, and in men, unwanted and sometimes prolonged erections.

Melanotan 1: from tanning agent to approved drug

The Australian company Clinuvel Pharmaceuticals licensed Melanotan I and renamed it afamelanotide. Two decisions turned it into a viable medicine:

1. A target that needed it. Instead of cosmetic tanning, Clinuvel focused on people for whom light is genuinely dangerous: patients with erythropoietic protoporphyria.
2. A controlled delivery system. Instead of frequent injections, afamelanotide is given as a small, dissolving implant inserted under the skin by a trained health professional, releasing the drug steadily over about two months.

The Canadian approval, announced by Clinuvel in July 2026, means Melanotan I now exists in Canada as a prescription medicine, but only as Scenesse, only for EPP, and only administered in specialist settings. That is very different from the vials sold online for tanning.

What EPP is, and the afamelanotide trials

Erythropoietic protoporphyria is a rare inherited disorder in which a light-sensitive chemical, protoporphyrin, builds up in the blood and skin. When exposed to visible light, even through a window, it causes severe burning pain, often without visible burns. People with EPP often organize their whole lives around avoiding daylight.

Afamelanotide’s approval rests on two randomized, double-blind, placebo-controlled trials published in the New England Journal of Medicine in 2015 (Langendonk and colleagues):

In both trials, quality of life improved, and side effects were mostly mild. In this population, a modest increase in pain-free time outdoors was meaningful.

Afamelanotide in vitiligo

Vitiligo is a condition in which patches of skin lose their pigment cells. In a randomized multicenter trial published in JAMA Dermatology in 2015, adding afamelanotide implants to narrowband UV-B phototherapy produced faster and greater repigmentation than phototherapy alone, especially on the face and upper limbs, and particularly in people with darker skin types. Clinuvel has continued to develop afamelanotide for vitiligo; it is not yet approved for that use.

Melanotan 2: the unapproved, more potent sibling

Melanotan II was never developed into an approved medicine. Its human data consist of small early-phase studies from the 1990s and 2000s:

• Dorr 1996: a pilot phase I study in three men showed tanning after only five low doses, along with nausea, yawning and spontaneous erections.
• Wessells 2000: two small placebo-controlled studies in men with erectile dysfunction showed MT-II produced erections without sexual stimulation in most participants, along with increased desire, but also frequent nausea and yawning.

Development moved to bremelanotide (PT-141) for sexual function, and to afamelanotide for skin. MT-II itself spread through gyms, tanning salons and online sellers from the mid-2000s onward, sold as “Barbie drug” or “tan jab”, entirely outside regulated medicine.

MT-II side effects

What’s known about MT-II’s side effects comes from the early studies plus case reports and surveys of unregulated use.

More detail is in Melanotan 2 side effects (French version: Effets secondaires du Melanotan 2).

Moles, melanoma and the skin cancer question

This is the most important safety question, and the evidence is uncertain in a way that should make anyone cautious.

What is documented: MT-II reliably darkens existing moles, and dermatologists have published multiple reports of new moles appearing and of moles changing in shape and colour in MT-II users. There are also published case reports of melanoma diagnosed in people using MT-II, such as a 2014 report from Denmark of a 20-year-old woman with fair skin who developed melanoma after a few weeks of MT-II injections combined with sunbed use.

What isn’t proven: case reports can’t establish that MT-II causes melanoma. Many users also use sunbeds and seek intense sun exposure, which are known causes of melanoma, and they are often fair-skinned and at higher baseline risk.

Why concern is reasonable anyway: MC1R activation drives melanocyte activity, and melanoma is a cancer of melanocytes. Darkened and changing moles are also harder to monitor, since colour change is one of the main warning signs dermatologists look for. A 2017 review of unregulated α-MSH analogue use concluded that the risks were real and underappreciated.

Who faces the highest risk

Dermatologists who have written about unregulated melanotan use point to several groups for whom the risks are greatest:

• Fair-skinned people who burn easily, often the most motivated to use melanotan, and also at the highest baseline risk of melanoma.
• People with many moles or atypical moles, or a personal or family history of melanoma.
• People combining it with sunbeds, which the WHO classifies as carcinogenic.
• People with heart or blood pressure problems, given the melanocortin system’s effects on blood pressure.
• Young adults, who feature heavily in published case reports.

Add the product-quality problem (unknown purity and sterility, possible mislabelling between MT-I, MT-II and PT-141) and the risk picture goes well beyond the molecule itself.

Does a melanotan tan protect against sunburn?

Partly, and less than people assume. Eumelanin does absorb UV, and the original Arizona research hoped a melanotan tan would reduce sunburn. Some studies of afamelanotide reported reduced sunburn cells after UV exposure. But:

• A tan, however produced, provides protection equivalent to only a low SPF.
• Most MT-II users combine it with sunbeds or deliberate sun exposure, which adds UV damage.
• The darker skin can create a false sense of security that leads to more sun exposure.

Sunscreen, shade and clothing remain the evidence-based protection. Afamelanotide’s approval is for reducing light-induced pain in EPP, not for sun protection in the general population.

What regulators say

• Health Canada: Melanotan II is not authorized for any use. In August 2025, Health Canada named both Melanotan 1 and Melanotan II among unauthorized injectable peptides seized from a Canadian seller marketing them for human use, and its April 2026 advisory warned against injecting peptides bought online. The only authorized Melanotan I product is Scenesse, the prescription implant for EPP.
• United States: afamelanotide (Scenesse) is approved for EPP. Melanotan II is not an approved drug.
• Europe and elsewhere: several national medicines agencies have issued public warnings about unlicensed melanotan tanning products over the years.

Melanotan timeline

Why MT-II spread despite never being approved

It’s worth asking why an unapproved, poorly studied compound became so widely used, because the same forces apply to many research peptides:

• The effect is visible. A tan is obvious within days, which makes people believe a product “works” even when the risks are invisible and delayed.
• It is cheap to make. A seven-amino-acid peptide costs little to synthesize, so it’s sold at low prices online.
• It spread through social settings. Gyms, tanning salons and social media, where peer recommendations carry more weight than regulatory warnings.
• Side effects were reframed as benefits. Appetite suppression and increased libido became selling points rather than signs of off-target brain activity.
• The approved sibling lent credibility. Afamelanotide’s approval is sometimes cited as if it applied to MT-II, which it doesn’t.

Where PT-141 fits

Bremelanotide (PT-141) is a close relative and metabolite of Melanotan II, developed to target sexual function rather than tanning. It went through phase 3 trials and was approved in the US in 2019 as Vyleesi for low sexual desire in premenopausal women; it is not authorized in Canada. Because it still activates MC1R, about 1% of trial participants developed darkened patches of skin. Full guide: What is PT-141?

Four myths about the melanotans

“Melanotan is FDA-approved.”

Afamelanotide, as a slow-release implant for EPP, is approved. Melanotan II, and Melanotan I sold in vials for tanning, are not approved anywhere.

“A melanotan tan means you can skip sunscreen.”

No. Any tan offers only low-SPF-level protection, and darker skin can encourage more sun exposure.

“MT-I and MT-II are basically the same.”

They differ in structure, selectivity, brain penetration, side effects and regulatory status. Only one went through phase 3 trials.

“Darker moles are just part of the tan.”

Darkening of existing moles is expected, but new moles or moles that change in shape, size or colour need a medical check, especially in fair-skinned people.

For researchers

The melanotans remain valuable tools in melanocortin research:

• Receptor selectivity studies: MT-I vs MT-II is a classic pair for separating MC1R effects from MC3R/MC4R effects.
• Melanogenesis assays: melanin production in melanocyte or melanoma cell lines (such as B16 cells), including comparisons with natural α-MSH.
• Structure-activity work: how cyclization changes stability, potency and selectivity.
• Anti-inflammatory signalling: MC1R activation also has immune effects, a growing area of research.

TrueLabs supplies Melanotan 1 and Melanotan 2 in 10 mg vials, each from $45, for in vitro research. Because MT-II and PT-141 differ by only a small structural change, mass spectrometry identity is the essential check; see How to read a peptide COA and the COA library.

See Melanotan 1 → See Melanotan 2 →

FAQ

Related reading

• Melanotan 2 side effects
• What is PT-141?
• Best anti-aging skincare ingredients
• How to spot fake peptides
• Research peptides in Canada

References

1. Levine N, et al. Induction of skin tanning by subcutaneous administration of a potent synthetic melanotropin. JAMA. 1991;266(19):2730–2736. PubMed
2. Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777–1784. PubMed
3. Wessells H, Levine N, Hadley ME, Dorr R, Hruby V. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000;12 Suppl 4:S74–S79. PubMed
4. Langendonk JG, Balwani M, Anderson KE, et al. Afamelanotide for erythropoietic protoporphyria. N Engl J Med. 2015;373:48–59. PubMed
5. Lim HW, et al. Afamelanotide and narrowband UV-B phototherapy for the treatment of vitiligo: a randomized multicenter trial. JAMA Dermatol. 2015;151(1):42–50. PubMed
6. Hjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology. 2014;228(1):34–36. PubMed
7. Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol. 2012;50(10):1169–1173. PubMed
8. Habbema L, et al. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. 2017;56(10):975–980. PubMed
9. Porphyria News. Porphyria treatment Scenesse approved in Canada. July 2026. Porphyria News
10. Health Canada. Advisory RA-77807: Unauthorized injectable peptide drugs seized and sold by Canada Peptide. August 1, 2025. Recalls and Safety Alerts
11. Health Canada. Think twice before injecting peptides bought online. Public advisory, April 9, 2026. Health Canada

This article summarizes published research and regulatory information for information only and is not medical advice. TrueLabs research compounds are sold for in vitro and laboratory research use only and are not intended for human or veterinary use.