the accidental side effect of a tanning drug
1996 (first documented clinical erection side effect); PT-141 isolated ~2000; Vyleesi FDA-approved 2019
A drug engineered to help a fair-skinned Arizona professor tan without sunlight and dodge melanoma ended up, purely by clinical accident, becoming the first on-demand FDA-approved treatment for low sexual desire in women.
In the 1980s, two University of Arizona pharmacology professors, Victor Hruby and Mac Hadley, were not thinking about sex — they were thinking about skin cancer. Hadley, who was fair-skinned and burned easily, wanted a way to switch on the body's own tanning machinery without a single ray of UV, as a melanoma-prevention trick. Starting from alpha-melanocyte-stimulating hormone, the pituitary hormone that darkens skin, Hruby's lab engineered sturdier, more potent synthetic knock-offs: Melanotan-I and the far stronger Melanotan-II.
The plot twist is in the peer-reviewed record, not just internet legend. In 1996, Robert Dorr and colleagues published a small Phase I study in the journal Life Sciences: three healthy men received escalating injections of Melanotan-II, and two of them tanned as hoped — but the researchers also logged something nobody had gone looking for, spontaneous erections lasting one to five hours, paired with an odd stretching-and-yawning reflex. (A more colorful version, in which Hadley himself allegedly self-injected a double dose and rode out an eight-hour erection with nausea, gets repeated everywhere — but see the myth-check.)
Sensing what they had, the university's tech-transfer arm licensed Melanotan-I to an Australian startup that became Clinuvel, and Melanotan-II to Palatin Technologies, a small New Jersey biotech. Palatin scrapped MT-II itself in 2000 — too much nausea, flushing and stomach cramping — and instead developed one of its metabolites, a near-twin differing by a single hydroxyl group in place of an amide, that homed in more cleanly on the brain's melanocortin-4 receptor, the arousal switch, with less of MT-II's baggage. The compound picked up the research code PT-141 (by a commonly repeated but unverified account, the 141st entry in Palatin's peptide library) and later the formal name bremelanotide.
From there the drug took a genuinely strange road. Palatin first aimed it at male erectile dysfunction, then tried an intranasal spray — which the FDA halted in 2007 over dangerous blood-pressure spikes — before reformulating it as a self-administered subcutaneous autoinjector and re-pointing it at an entirely different target: hypoactive sexual desire disorder in premenopausal women. In June 2019 the FDA approved it as Vyleesi, the second-ever drug for female sexual dysfunction (after flibanserin/Addyi) and the first taken as-needed rather than daily. A compound born from a suntan experiment on men had become a prescription desire drug marketed exclusively to women.
The science checks out: the 1980s Arizona tanning research, the 1996 study that accidentally documented erections, the Clinuvel/Palatin licensing split, the 2007 nasal-spray halt, and the 2019 Vyleesi approval are all independently corroborated. What doesn't clear the bar is the vivid tale that Professor Hadley personally self-injected a double dose and endured an eight-hour erection — every version traces back to a single source (his own later retrospective), so we treat it as an origin myth rather than established fact.
Today <b>Vyleesi</b> is still FDA-approved and on the market, now sold by <b>Cosette Pharmaceuticals</b> after passing through several owners (King, AMAG, and Fosun Pharma for the China market). It carries warnings for transient blood-pressure spikes, nausea (the most common side effect, hitting roughly 40% of users) and fainting, and it is cleared only for premenopausal women with acquired, generalized HSDD — not for men, despite the male-erection origin story and persistent off-label use. Meanwhile the parent compound, <b>Melanotan-II</b>, never earned any medical approval and lives on as an unregulated gray- and black-market \"tan jab\" — a tanning injection or nasal spray popular in the UK and fueled by social media, despite documented risks including melanoma, kidney injury and dangerous priapism. One 1980s research program, two afterlives running in parallel: an approved drug for a use nobody was hunting for, and a banned-in-spirit street drug for the exact suntan it was originally built to deliver.
