Melanotan II vs Melanotan I
It is an injection sold for a deep tan, less appetite and better erections. The only study had 3 men, and the rest is case reports of harm, including changing moles. Sold as a safe way to tan without sun. It darkened skin in a 65-person trial. The approved version is a different product for a rare sun-pain disease.
Melanotan I has the stronger evidence, grade B (some human evidence) against grade C for Melanotan II. Neither is FDA approved.
Evidence
CAnimal and cell studies
BSome human evidence
Human studies cited
Animal or cell studies cited
Why the grade
The human evidence is a 1996 pilot phase 1 study in three men, plus case reports of melanoma and changing moles in users. No controlled trial of Melanotan II has been published for tanning or any other use.
For the tanning use it is sold for, the evidence is one placebo-controlled trial in 65 fair-skinned volunteers that measured melanin density and UV damage markers, a surrogate for sunburn protection. The approved use in erythropoietic protoporphyria rests on two randomized placebo-controlled trials totaling 168 patients. The tanning use has one trial with surrogate endpoints, which is B; no trial has tested cosmetic tanning in the general population or compared it with sunscreen.
FDA
Not approved
Not approved by the FDA for any use and sold as an unregulated gray-market product. Melanotan II was nominated for the FDA's list of substances compounding pharmacies may use and placed in Category 2 (significant safety risk); the nomination was withdrawn and the FDA removed it from that category in April 2026, with an advisory committee review planned, which does not make it legal to compound or sell.
Not approved
Melanotan I is the same molecule as afamelanotide, which the FDA approved in 2019 as the Scenesse implant for adults with erythropoietic protoporphyria. Injectable 'Melanotan I' sold online for tanning is not approved by the FDA for any use and is sold as a research chemical.
Sold for
Melanotan II is the 'Barbie drug' of gym and tanning culture, sold online as an injectable that gives a deep tan, suppresses appetite, and improves erections.
Melanotan I is sold as the 'safer' tanning peptide, the one that became a real drug, promising a tan without sun and protection against burning.
Studies say
A three-man pilot study in 1996 showed it darkens skin and causes erections and nausea, and the rest of the literature is case reports of harm, which is grade C evidence.
A 65-person placebo-controlled trial showed more melanin and less UV damage in fair skin, and two trials in 168 porphyria patients led to approval of the implant, so the evidence is grade B for tanning and the approved product is a different formulation for a rare disease.
Class
Melanocortin agonist (MC1R/MC3R/MC4R)
MC1R agonist
Route
Injection
Injection