A tan can come with other effects
Melanotan 2 may affect more than your skin.
Here's what happened to people, mice, and rats. You'll also see the harms that doctors can't yet put a number on.
Skin, hunger, and sex drive may all change
A dark patch can appear even if you haven't sat in the sun. Melanotan 2 copies a hormone that orders your skin to make brown color.
That hormone also helps guide hunger and sexual interest. In one small study, the men's skin darkened, and they had erections they hadn't sought [1].
Mice and rats ate less, while males had erections or acted in new ways. Animal work can't say how you might react.
Here's the part I'd hold onto: no drug agency has approved Melanotan 2 [4]. Doctors have treated painful erections that lingered, dark moles, and kidney harm.
You can read those cases on the effects page. This isn't a clinic, and you won't find the drug for sale here.
Brain studies may explain why several effects arrive together
A tan and less hunger can seem unrelated. Melanotan 2 reaches brain areas that help govern food and sexual interest.
Researchers placed the drug in a reward area deep in male mice's brains. Afterward, the animals ate less and pressed the food lever fewer times [5].
In rats, the drug prompted brain cells to release oxytocin, a hormone that helps with bonding [8]. In 2024, voles met another vole while researchers watched that same reward area.
A second drug blocked oxytocin, and then the reward area didn't grow more active [9]. These animal tests can't measure the chance that you'd feel any similar change.
To see how such changes may begin, read the melanotan 2 mechanism of action page. You won't need a list of lab codes.
The few human studies can't settle the safety question
The human work is old and very small. It can't give you or your doctor a sound safety answer.
A skin study included 3 healthy men. Skin darkened in 2 of the 3 after 5 doses, and some felt sick or had erections they hadn't sought [1].
Those facts describe a test; they aren't directions for using Melanotan 2. The drug has no approval for human use.
A second study included 10 men whose doctors found no physical cause for their erection trouble. The drug caused an erection in 8 of the 10, lasting longer than after a placebo, or sugar shot [2].
No large later test of Melanotan 2 has been finished [4]. So the human work can't forecast your result.
Doctors reported painful erections, changed moles, and kidney injury
You might first notice a new mole or one that suddenly looks darker. Some users were later diagnosed with melanoma, a skin cancer [10].
Part of one person's kidney stopped receiving blood. Other reports described severe muscle damage followed by failed kidneys [4].
A vial brings another risk before anything enters your body. Tests of goods sold online found wrong labels, different strengths, and material that shouldn't be there.
You can't see those faults through the glass. A clean-looking vial may still hold something different from its label.
Each case is explained on the Melanotan 2 effects page. Human and animal findings stay separate on the Melanotan 2 research page.