What Is the 'Barbie Peptide' and Why Is It Risky?

 An unregulated injectable peptide popping up across social media promises a sunless tan, but the product -- melanotan II, also known as the "Barbie peptide" -- carries risks, dermatologists said.

"People want to use this peptide to basically get a tan without getting UV [ultraviolet] exposure. So what it does is, it tells the cell to produce pigment," explained Raman Madan, MD, chief of dermatology at Northwell Health's Glen Cove Hospital in New York.

Peptides are short chains of amino acids that act as "messengers to the body," Madan told MedPage Today. "You can build peptides to seek out certain cell receptors."

In the case of melanotan II, this synthetic peptide mimics a hormone that is already present in the body -- alpha-melanocyte stimulating hormone (α-MSH) -- which binds to the melanin receptors responsible for pigmentation of the skin.

The melanocortin 1 receptor (MC1R) activated by α-MSH stimulates production of melanosomes that produce eumelanin or pheomelanin, two subtypes of pigment, explained Michael Christopher, MD, of Ironwood Dermatology in Tucson, Arizona. "Melanotan stimulates that same receptor," he added.

Christopher first started hearing about these injectable peptides from the bodybuilding community just before the COVID-19 pandemic. Some people argue that they create a "base tan" that protects them from the sun, he said.

"You're creating more basal pigmentation in the skin," he noted. "But in doing so, you don't know if you're also just increasing your risk of developing a melanoma."

A small number of case reports have linked peptides to darkening of already existing moles. "For some people, that could just be a benign phenomena, but it could also be turning into a deadly cancer," Christopher said.

Studies of patients with melanoma have found that MC1R is activated by UV light, he noted. A 2024 study suggested that the receptor may be a "valuable drug target in aggressive melanoma."

"Anything that is activating MC1R ... gives me concern for potentially increasing the risk of somebody developing melanoma," Christopher said.

Other reported side effects with melanotan include rhabdomyolysis and priapism. A 2019 case report described a 41-year-old Scottish man who endured a 22-hour "painful, unrelenting penile erection" following a melanotan injection. Other studies have linked melanotan II to renal infarction, which can be life-threatening.

A study on the experience of 29 self-reported melanotan II users found all participants experienced an increased tan; however, some reported a dull gray color. Side effects including nausea, flushing, and fatigue did not appear to discourage further use of the peptide, and participants were "generally unconcerned with long-term adverse effects."

As with any unregulated product, the full scope of adverse events is still unknown, Christopher said. As someone who specializes in melanoma, he is not recommending melanotan II to anyone.

If the product was truly as beneficial as those selling it claim, clinical trials would have been initiated, he argued.

The pharmaceutical industry has found ways to profit from effective peptides, including GLP-1 receptor agonists for type 2 diabetes and obesity, among other conditions, Christopher said. "There is a reason why none of this stuff that has been around for years has been converted into an actual drug," he added.

Another trend buzzing on social media is "tanmaxxing," which is tanning outside during the highest UV hours of the day. While that is a "natural way" to increase pigment, it also increases a person's risk of skin cancer, Christopher noted.

"Essentially, they're burning their skin," he said, and the fact that some people may be participating in both trends at once is worrying.

People are getting advice from influencers, mostly non-physicians, he pointed out. "They're saying that ... the things that are natural and are not being pushed by pharma are going to make you live longer and be healthier, and they don't mention all of their conflicts of interest."

"There's a lot of bro science ... 'Don't listen to your doctor. Listen to this wellness influencer,'" Christopher said. "And I think a lot of people are, unfortunately, taking that advice."

A safer alternative is artificial tanners, he advised. While they may stain your clothes, they are completely safe for your body.

https://www.medpagetoday.com/popmedicine/cultureclinic/122362