Key points
- Bremelanotide (PT-141) was tested in two phase 3 trials with 1,267 women. The benefit was statistically significant but modest [7][8].
- A 2024 critical analysis noted that 8 of the 11 registered efficacy outcomes had not been published. When analyzed, effects were “nil to small” [8].
- Melanotan use has been linked in reports to eruptive moles, changes in existing moles and four melanoma cases, without conclusive proof of causation [1][2].
- There are also isolated reports of priapism and kidney infarction after melanotan use [5][6].
US status (October 2026): PT-141 is bremelanotide, approved as Vyleesi for premenopausal women with acquired, generalized hypoactive sexual desire disorder, and a 503A pharmacy may compound it for a named patient within the essentially-a-copy rules. For melanotan II, see the peptide status tracker.
The two molecules share a receptor family and a chemical origin. The difference is evidence: bremelanotide has measured, modest, debated benefit from controlled trials. Melanotan II for tanning has case reports and no trials.
Both started as alpha-MSH analogs
Melanotan II and bremelanotide (PT-141) are analogs of alpha-melanocyte-stimulating hormone (α-MSH) and act on melanocortin receptors [1][7]. The first became famous as the “tanning peptide.” The second was developed as a medicine for hypoactive sexual desire disorder in premenopausal women and went through controlled trials to FDA approval [7][9].
PT-141 is approved, and its effect size is debated
In the two RECONNECT phase 3 trials (1,267 women), bremelanotide was associated with a 0.35-point increase in desire and a 0.33-point reduction in distress vs placebo (both P < .001). Nausea, flushing and headache occurred in at least 10% of participants [7].
The debate is about effect size. A 2024 analysis noted that 8 of the 11 efficacy outcomes registered on clinicaltrials.gov had not been published. Analyzing them, it found “nil to small” effects, and it also questioned the validity of the scales used in the trials [8].
- 1,267: women in the bremelanotide phase 3 trials [7]
- 4: melanoma cases reported during or shortly after melanotan use [1]
- 24 h: for eruptive moles to appear after a single melanotan II injection [3]
Melanotan evidence is case reports
There are no controlled trials of melanotan for cosmetic use. What exists are case reports and series. A 2017 review described changes in existing moles, new moles (some dysplastic) and four melanoma cases arising during or shortly after use, while noting that conclusive evidence of a link is lacking [1]. In a review of 179 patients with eruptive nevi, immunosuppressants, chemotherapy or melanotan accounted for 41% of suspected causes [2].
Some reports stand out for their speed: eruptive moles and darkening of existing moles 24 hours after a single injection of melanotan II [3]. In 2025, an oral mucosal melanoma was reported in a 22-year-old woman who had used melanotan II nasal spray for tanning. The authors framed it as a possible risk factor [4].
The reports extend beyond the skin
There are also isolated reports of priapism [5] after a melanotan injection and kidney infarction most likely attributed to melanotan II [6]. The same paper cites earlier cases of rhabdomyolysis and kidney failure [6]. These are individual cases. They can raise a signal, but they cannot measure the risk.
Controlled trials are the underlying difference
Bremelanotide went through controlled trials, and its benefit, though modest and debated, has been measured [7][8]. Using melanotan II for tanning is unregulated, and its safety profile rests on case reports, which flag possible risks without being able to quantify them [1][2].
What this means for your clinic
If a patient asks about PT-141, you have an approved molecule with a labeled indication and a known side-effect profile. Product sold online as “PT-141 peptide” with a “research use only” label is a different thing. If a patient mentions tanning injections, ask about new or changing moles and examine the skin. The peptide program we run follows the status tracker, compound by compound.
References
- Habbema L, et al. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. 2017;56(10):975-980. PMID 28266027. Link
- Burian EA, Jemec GBE. Eruptive melanocytic nevi: a review. Am J Clin Dermatol. 2019;20(5):669-682. PMID 31119650. Link
- Schulze F, et al. Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II. Eur J Dermatol. 2014;24(1):107-9. PMID 24334249. Link
- Yassin Alsabbagh A, et al. Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma? Int J Oral Maxillofac Surg. 2025;54(9):806-808. PMID 40210573. Link
- Dreyer BA, et al. Melanotan-induced priapism: a hard-earned tan. BMJ Case Rep. 2019;12(2):e227644. PMID 30796078. Link
- Peters B, et al. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep. 2020;9(2):159-161. PMID 31953620. Link
- Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134(5):899-908. PMID 31599840. Link
- Spielmans GI, Ellefson EM. Small effects, questionable outcomes: bremelanotide for hypoactive sexual desire disorder. J Sex Res. 2024;61(4):540-561. PMID 36809187. Link
- U.S. Food and Drug Administration. Vyleesi (bremelanotide injection) prescribing information. NDA 210557, 2019. Link
This is general information, not medical or legal advice. Rules vary by state and change. Confirm your own facts with counsel.