Read this part first
Melanotan II stimulates melanocytes — the same cells involved in melanoma. Multiple case reports describe changes in the size, shape and colour of existing moles in users, and new melanoma diagnoses following use. Causation is not proven. But the mechanism is plausible, the reports are consistent, and the compound has never undergone the safety testing that would resolve the question.
If you have used Melanotan II and have a mole that has changed, see a GP. Do not wait to see whether it settles.
Regulatory position
Melanotan II is unlicensed in the UK and has never been approved by any medicines regulator anywhere in the world. Supplying or advertising it is illegal.
The MHRA has issued repeated public warnings, has contacted suppliers to inform them that supply and advertising are unlawful, and has shut down large numbers of websites offering it to UK customers. Regulators in the US, Ireland and Australia have issued equivalent warnings.
This is worth sitting with. Most unlicensed peptides are simply undeveloped — nobody took them through trials. Melanotan II is different: it has been actively warned about, by name, by multiple national regulators, over a period of years.
Reported adverse effects
The MHRA has received reports describing multiple distinct reaction types linked to melanotan use, including gastrointestinal and cardiac problems and blood and eye disorders. Beyond the regulatory reporting, the published case literature and consumer safety warnings describe:
- Changes to moles — size, shape, colour and number. This is the signal that matters most.
- Nausea and vomiting, often immediately after use.
- Raised blood pressure.
- Rhabdomyolysis — muscle breakdown that can cause kidney injury.
- Priapism — prolonged painful erection, a urological emergency, arising from the compound's non-selective melanocortin activity.
- Kidney infections and renal failure in severe reported cases.
The nasal spray problem
Nasal tanning sprays containing Melanotan II are being marketed as cosmetics, which sidesteps the regulation that applies to medicinal products. The Chartered Trading Standards Institute has issued warnings, and Melanoma Focus has raised concern about their promotion on social media to young people.
Relabelling a medicinal compound as a cosmetic does not change what it does in the body. It only changes which rules the seller is pretending to follow.
Nasal administration also removes the one thing people often cite as reassurance — that they can see what they are injecting. It does not reduce systemic exposure.
The injection route adds its own risks
Separate from the compound: these products are self-injected, frequently sold in gyms, salons and through social media, and shared. Needle sharing and non-sterile technique carry infection risks entirely independent of Melanotan II itself.
What about Melanotan I?
They are not the same, and the distinction is genuinely important. A Melanotan I derivative, afamelanotide, has been licensed as a specialist treatment for a rare light-sensitivity disorder, administered as an implant under medical supervision. That does not extend to Melanotan II, which has no approved form anywhere.
Where this leaves you
There is no version of this where the evidence supports cosmetic use. The compound produces the intended effect, has never been shown to be safe, is illegal to supply, has been repeatedly warned about by regulators, and carries a plausible and unresolved association with melanoma.
If a tan is the goal, topical self-tanning products achieve it without any of this.