This page is the side-effect record for melanotan I and II, the peptides sold for tanning, counted by the kind of source each finding comes from. The overview of what melanotan is and how regulators treat it is on our tanning peptides page. Nothing here is a guide to use, and nothing here says any product is safe or unsafe. It sets out what has been reported, by whom, and what each type of source can and cannot establish. Anyone with symptoms after using one of these products, or with a mole that has changed, is best served by a doctor.
Three kinds of evidence, and what each can show
| Source | What it is | What it can show | What it cannot show |
|---|---|---|---|
| Clinical trials | Small, supervised studies from the 1990s–2000s | Effects seen in a few volunteers given a known product | Rare or long-term effects; anything about online products |
| Case reports | A doctor's account of one or a few patients | That an event happened in someone using the product | Cause, or how often it happens |
| Regulator databases | Spontaneous reports sent to the MHRA or FDA | That people suspected a link | Cause, frequency, or even that the product was melanotan |
What the trials reported
The trials were small and supervised, and used pharmaceutical-grade material from the research groups that made it.
- Melanotan II, 1996 pilot (3 men). Nausea "at most MT-II dose levels", grade II sleepiness and fatigue in one of the two men at the highest level, a stretching-and-yawning pattern, and spontaneous erections lasting one to five hours after each dose (Dorr et al., PMID 8637402).
- Melanotan I, 1997 (3 men). "Occasional gastrointestinal upset and facial flushing" (Ugwu et al., PMID 9113347).
- Melanotan I, 2004 (three small phase I studies). Designed to test safety with measured UV exposure; they report tanning results rather than a new class of harm (PMID 15262693).
That is the complete controlled record for tanning. No trial followed users for more than a few weeks after dosing.
The 26 case reports, named
On 24 September 2026, PubMed's "case reports" publication type returned 28 records for melanotan (the same filter returns 161 for retinol). Two are false matches on the abbreviation MT-II, which also means metallothionein II. The other 26 are listed here.
New, darkened or atypical moles — 9
- Cousen 2009, eruptive moles after injection (Br J Dermatol, PMID 19575725)
- Ferrándiz-Pulido 2011, an eruptive pigmented lesion (PMID 21933235)
- Thestrup-Pedersen 2011, lentigines and moles, Denmark (PMID 21453640)
- Hueso-Gabriel 2012, eruptive dysplastic moles, Spain (PMID 22425244)
- Mang 2012, dermoscopic changes in existing moles, Germany (PMID 23052015)
- Sivyer 2012, changes in a teenager with a hereditary multiple-mole syndrome who also used sunbeds (PMID 23785612)
- Burian 2013, the first two Swedish cases of eruptive moles (PMID 23451671)
- Reid 2013, atypical moles, Ireland (PMID 23914578)
- Schulze 2014, eruptive and darkened moles 24 hours after a single injection (PMID 24334249)
Melanoma — 3
- Paurobally 2011, "melanotan-associated melanoma" (Br J Dermatol, PMID 21564053)
- Yassin Alsabbagh 2025, a mucosal melanoma of the upper jaw in a 22-year-old woman who had used a melanotan II nasal spray for tanning; the authors frame it as "a possible risk factor" (PMID 40210573)
- Vadner 2026, five melanomas in situ in one patient who had also used tanning beds and anabolic hormones (PMID 42328529)
Other pigment changes — 2
- Paurobally 2013, dark bands across the nails (PMID 22182016)
- Bonchev 2026, changes in the lining of the mouth (PMID 41752902)
Serious effects beyond pigment — 6
- Nelson 2012, systemic toxicity and rhabdomyolysis (muscle breakdown) after an injection bought online, from a US poison centre (PMID 23121206)
- Kaski 2013, posterior reversible encephalopathy syndrome, a form of brain swelling (Ann Intern Med, PMID 23648958)
- Dreyer 2019 and Mallory 2021, priapism, a painful erection that does not subside (PMIDs 30796078, 33460908)
- Peters 2020, kidney infarction, with a review of earlier kidney cases (PMID 31953620)
- Dickson 2025, pyoderma gangrenosum, an ulcerating skin condition (PMID 41487785)
Identification, public-health and behaviour reports — 6
- Affleck 2010, on body dysmorphic disorder among users (PMID 19919633); Knudsen 2012 and Eijmael 2022, articles on the risks of the "Barbie drug" in Swedish and Dutch medical journals (PMIDs 23193937, 35736369); Van Hout 2014, one user's account (PMID 24280586); Adler 2017, unregulated use as "of public health interest" to Australian dermatologists (PMID 28905366); Deville 2024, forensic identification of seized products (PMID 39302005).
Two patterns stand out. Twelve of the 26 concern moles or melanoma, the effect most directly linked to how the drug works. And several of those patients were also using sunbeds or other drugs, which the reports themselves note and which no case report can untangle.
What regulators' databases hold
- UK (MHRA). 16 suspected adverse-reaction reports for melanotan II between 1 January 2012 and 31 December 2022. The regulator adds that inclusion "does not necessarily mean that the events were caused by the product" and that report numbers do not equal the number of people affected (FOI 24/274, 17 April 2024).
- US (FDA FAERS). 9 reports naming melanotan II on 24 September 2026, 8 marked serious. The most frequent reaction terms were renal artery thrombosis (5) and renal infarct (3), which matches the kidney case literature and may include the same patients. FAERS reports are unverified and can be duplicates.
Both counts are tiny against the scale of online sales implied by regulators' repeated removal actions. A low report count for an illegally sold product reflects who reports, not how often harm occurs.
What has never been studied
- Any effect over years, for either compound, at any level of use.
- How often mole changes or melanoma occur in users, compared with non-users of similar sun habits.
- The effects of nasal sprays as sold, whose contents regulators say are unknown.
- The combination with sunbeds, beyond the measured UV doses in the small Arizona studies.
- Effects in pregnancy, which none of the trials or case reports address.
The regulated relative, afamelanotide, has an FDA label for a rare light-sensitivity disorder; it is described on our tanning peptides page and in Peptide Lexicon's melanotan I entry. For how pigment and peptides interact in ordinary skincare, see peptides for skin.