You may have seen “tanfluencers” on social media pushing the use of melanotan II—which has been dubbed the “Barbie peptide”—as a way of quickly getting a tan without the sun. But before you “Barbie-cue” your skin in such a manner to get darker, consider the potential risks—such as rhabdomyolysis and melanoma—of this medication that has not been approved by the U.S. Food and Drug Administration. And think hard about what happened to a 41-year-old Scottish man who injected melanotan and then experienced a 22-hour unrelenting painful erection. Yes, that’s right, 22 hours.
How Does The ‘Barbie Peptide’ Work
Melanotan II is known as the “Barbie peptide” because, one, it’s a peptide—which is a short chain of amino acids that can serve as a messenger in the body. And, two, it’s being touted as a way to give you the lean, tanned look of a Barbie doll without ultraviolet radiation exposure. Such a look may seem enticing because who doesn’t want to look like a Barbie doll, with a waist so narrow that it couldn’t possibly house a normal-sized liver and intestines and an elongated neck that could give an ostrich a run for its money.
Yes, a Barbie doll is not exactly natural and the same can be said about melanotan II. This synthetic peptide is designed to mimic a hormone that you should already have in your body—namely alpha-melanocyte stimulating hormone or α-MSH. It’s called “melanocyte stimulating” because stimulate is what it does to melanocytes, the cells in your skin that produce various pigments—known as melanin—that give your skin its color. When α-MSH binds to melanocortin 1 receptors, it stimulates the production of melanosomes in melanocytes that in turn produces two types of pigments: eumelanin or pheomelanin. Injecting melanotan II under your skin can presumably do the same thing.
The ‘Barbie Peptide’ Has Become Part Of ‘Tanmaxxing’
That’s why certain “tanfluencers”—which is a portmanteau of “tan” and “infleuncers”—have been touting melanotan II as part of the “tanmaxxing” arsenal. Back in May, I covered in Forbes this whole tanmaxxing social media trend, which is about encouraging people to get deeper and darker tans. The argument for such tanning is that it will make you look leaner and more muscular—sort of like what happens when you put a chicken on a rotisserie. But trying to get tanner through more UV light exposure can bring lot of dark, dark risks—such as damaging your skin and in the process raising your risk of skin cancer.
At first blush, cancer may not seem to be a concern with using the “Barbie peptide,” since it can in theory get you darker without UV radiation. In fact, some tanfluencers are saying that taking melanotan II can give a “base tan” that will actually protect you from the sun. The reality, though, may be much more dark.
The ‘Barbie Peptide’ Could Raise Your Risk Of Melanoma
Playing around with your melanocytes in such a manner could be playing with fire. Just look at the case reports of people injecting themselves with melanotan and then having their moles subsequently get darker or even developing melanoma. Of course, case reports alone are not enough to establish a clear link between melanotan and cancer or quantify the risk. At the same time, though, there haven’t been enough full studies of melanotan to establish its safety. That’s why no forms of melanotan II—whether it’s the injectable or nasal spray versions— have been approved by the U.S. FDA for use.
Moreover, in a study of 29 users of Melanotan II published in the Journal of the American Academy of Dermatology, some users reported their skin turning a dull gray color. That may not be the color that you are aiming for unless you are following some kind of a #koalamaxxing trend. That same study found users to have experienced other side effects such as nausea, flushing and fatigue.
The ‘Barbie Peptide’ Could Lead To Rhabdomyolysis Or Renal Infarction
Depending on who you are, turning the color of a pigeon may not be that distressing. But other potential side effects such rhabdomyolysis should be. Rhabdomyolysis is where your muscles break down or basically disintegrate, as I’ve detailed before in Forbes. That obviously is not a good look. But it also life-threatening because the breaking down of muscle fibers release all sorts of muscle fiber components like potassium, phosphate, myoglobin, creatine kinase or urate into the bloodstream. These can overwhelm and damage your kidneys, leading to kidney failure.
Another potential concern with melanotan II use is renal infarction. A publication in CEN Case Reports presented a case report of this. Renal infarction is when the flow of blood to your kidney gets blocked, leading to the death of kidney tissue. Depending on how much kidney tissue ends up being lost, this can be life-threatening as well.
The ‘Barbie Peptide’ Led To A 22-Hour Painful Erection
But what may have stood out to you at the beginning was this case report of the painful 22-hour erection, published in the journal BMJ Case Reports with the title, “Melanotan-induced priapism: a hard-earned tan.” If you haven’t guessed yet, priapism is where you have an erection that last for more than four hours without sexual desire. It occurs when blood gets trapped inside your penis and cannot flow back out, which is a medical emergency.
The Scottish man who underwent this hardship had occasionally experienced one-to-two hour prolonged erections after injecting melanotan into his abdomen. But this was the first time the erection had been painful. And it was the first that it had lasted around 22 hours, which is more than twice as long as the entire Lord of the Rings movie trilogy. In the emergency room, repeated injections of phenylephrine into his penis eventually brought things down.
As should be clear by now, melanotan is not a “Come on, Barbie, let’s go party” situation. This is not a tan do situation as using this unapproved medication can have some really dark consequences.

