Melanotan II, the unlicensed synthetic tanning peptide illegal to sell in the UK, has been linked to a growing list of alarming side effects, but doctors are now highlighting one in particular that most users would never anticipate and that can cause permanent damage if left untreated.
The so-called "Barbie drug" works by stimulating melanin production in the skin, darkening it without UV exposure. It is available as a nasal spray or injection and remains popular despite being unregulated and untested, with Cancer Research UK warning that it "is not safe to use" and that its full side effect profile remains unknown.
While nausea, facial flushing, increased libido, darkening of moles and reduced appetite are among the more commonly reported effects, a case study published in the journal Sexual Medicine has documented one of the more extreme consequences the drug can produce in men.
A 55-year-old patient arrived at a hospital in Miami with a painful, sustained erection that had lasted 30 hours. He had been using Melanotan II for more than six years to maintain his tan and told doctors that he would typically experience an erection of a few minutes after each injection. On this occasion, it had not stopped.
The condition, known as priapism, is a prolonged erection unrelated to sexual stimulation that can cause permanent damage if not treated promptly. According to the NHS, treatment involves draining blood from the penis using needles or a small surgical incision. In this patient's case, surgical intervention was ultimately required, and at a follow-up appointment 15 weeks later, he reported new onset erectile dysfunction.
The case study noted that Melanotan II, while marketed as a tanning aid, also functions as a sexual stimulant and has been investigated as a potential treatment for erectile dysfunction, which explains why the drug acts on more than just skin pigmentation.
A separate study found that 8 out of 10 men with erectile dysfunction who took Melanotan II experienced visible erections as a result. Transient side effects including nausea and reduced appetite were also reported across the group.
Doctors and dermatologists have been raising the alarm about the drug more broadly, with experts warning that unregulated products bought from overseas websites offer no guarantee of purity or safety. Dr Sobia Kauser of the University of Bradford put it plainly: "You are essentially injecting a chemical into your body with unknown impurities. Is this the price you are willing to pay to look more attractive?"
The more serious documented risks include dysplastic naevi, renal infarction, an increased risk of melanoma and, as this case demonstrates, the kind of priapism that requires a trip to hospital and can result in lasting sexual dysfunction.
