Melanotan II.

"Melanotan 2 is a synthetic peptide that absolutely produces a tan, that part is real, but it is not selective, so along with the tanning receptor it also hits receptors that cause nausea, stomach cramps, flushing of the skin, fatigue, decreased appetite, and in men spontaneous erections within one to five hours of injection. Beyond that there are documented cases of rhabdomyolysis leading to kidney failure, renal infarction, and priapism serious enough that surgery was needed to save function. There are also multiple published case reports linking Melanotan use to melanoma, and because it directly stimulates your melanocytes, the exact cells that become melanoma, this is the reason I would never recommend this peptide to anyone. It is an unregulated, non-FDA-approved product usually sold as a powder online with no quality control and no standardized dosing, so people end up having to be their own chemist calculating their own dose, and the reality is this is not worth the risk."

"MT2, Melanotan II, is a tanning peptide that's been around a while but is having a resurgence because the FDA recently reclassified it, making it legal for compounding pharmacies to manufacture. It's a non-specific peptide, it doesn't just hit the melanocortin 1 receptor, it hits others, and that's where some of the side effects come from. If you have existing moles or freckles they'll get darker, and there are case reports of people developing melanoma while taking it, some within three months of starting and one after only a single dose. It can also cause erections that last more than four hours, which is a medical emergency, and there are case reports of people needing surgery over it. Most people are buying it off unregulated websites where you can't guarantee the safety or purity of the product. The spray version isn't safer either, it's probably less effective than the injection form, and the convenience actually makes it more dangerous because it's more accessible to people. This is a risky peptide and I don't encourage its use. If you're on it, stop and go get checked by a dermatologist."