# Melanotan Side Effects: What the Research Shows

> melanotan side effects documented in Phase I trials and case reports: nausea, renal infarction, rhabdomyolysis, dysplastic nevi, and mucosal melanoma. Full adverse-event record with citations.

## Nausea and Flushing: Dose-Dependent Observations

Nausea, facial flushing, fatigue, yawning, and stretching are the most consistently documented adverse events across Phase I trials and observational data. These were the most common adverse events in the 1996 Dorr Phase I study and in the Wessells 1998 crossover trial [3][5][6].

The nausea and autonomic side effects are mechanistically attributable to central MC4R activation: the Paiva 2017 rat study demonstrated that IV MT-II induced Fos expression in hypothalamic magnocellular neurons and increased oxytocin neuronal firing [26]. Nausea was generally dose-dependent and transient in Phase I. The 2021 qualitative study of 623 forum entries from 205 self-administered MT-II users confirmed nausea and facial flushing as the predominant adverse themes [23].

## Renal Adverse Events in the Literature

**Case 1: Renal infarction (Peters et al. 2020).**
A 45-year-old male who self-administered 27 mg of MT-II subcutaneously over 6 months developed right-sided renal infarction affecting approximately 50% of the kidney. CRP 152 mg/L, elevated creatinine (102 µmol/L), hematuria, hypertension (165/95 mmHg). CT confirmed the infarction. Follow-up renal function: 81 mL/min per 1.73 m² (mildly reduced). Proposed mechanism: thrombotic pharmacological effects at cumulative high doses [11].

**Case 2: Rhabdomyolysis and AKI (Nelson & Bryant, 2012).**
A 39-year-old man injected 6 mg MT-II subcutaneously in a single dose (approximately 6x the Phase I starting dose). CPK peaked at 17,773 IU/L at 12 hours, confirming rhabdomyolysis; creatinine 2.25 mg/dL indicated acute kidney injury. ICU admission for 3 days required [12].

Both cases involved doses substantially above the Phase I study range.

## Mole Changes and Melanocytic Nevi

**Case 1 (Hueso-Gabriel et al. 2012).** A 25-year-old man developed sudden eruption of multiple melanocytic nevi and rapid transformation of existing nevi after Melanotan use. Histopathology: dysplastic melanocytic nevi with severe dysplasia [13].

**Case 2 (Sivyer 2012).** A 16-year-old female with FAMMM syndrome developed multiple dark melanocytic nevi, including an enlarging nevus in the left groin. Histopathology: dysplastic compound nevus with moderate cytoarchitectural atypia. Three months after cessation, moles lightened [14].

Mechanism: increased MC1R stimulation activates melanocytes in and around nevi — potentially destabilizing existing nevi and stimulating new melanocyte proliferation.

## Mucosal Melanoma (2025 Case Report)

A 2025 case report documented a 22-year-old female who developed mucosal malignant melanoma of the anterior maxilla following use of unlicensed MT-II nasal spray for cosmetic tanning [25].

A 2026 case report documented oral mucosal pigmentation (400 µg every other day, 64 days cumulative) with partial reversal after cessation [24].

## Safety Profile Summary

MT-I (afamelanotide/Scenesse) has an established safety record in regulated clinical trials — 1,023 implants over 8 years with only minor adverse events [16]. MT-II lacks equivalent regulatory review. Controlled Phase I data documented nausea as the predominant adverse event at 0.025 mg/kg. Serious adverse events derive entirely from case reports of self-administered, uncontrolled use at doses substantially above the Phase I range.

**Regulatory status:** MT-II has no approved indication (FDA, TGA, HPRA, MHRA). WADA classifies MT-II under S0 (Non-Approved Substances). Prohibited in sport.

## References

[3] Dorr RT et al. Evaluation of melanotan-II in a pilot phase-I clinical study. Life Sci. 1996. PMID: 8637402
[5] Wessells H et al. Synthetic melanotropic peptide initiates erections. J Urol. 1998. PMID: 9679884
[6] Wessells H et al. Melanocortin receptor agonists, penile erection. Int J Impot Res. 2000. PMID: 11035391
[11] Peters B et al. Melanotan II: a possible cause of renal infarction. CEN Case Rep. 2020. PMID: 31953620
[12] Nelson ME, Bryant SM. Melanotan II injection: systemic toxicity and rhabdomyolysis. Clin Toxicol. 2012. PMID: 23121206
[13] Hueso-Gabriel L et al. Eruptive dysplastic nevi following melanotan use. Actas Dermosifiliogr. 2012. PMID: 22425244
[14] Sivyer GW. Changes of melanocytic lesions induced by Melanotan. Dermatol Pract Concept. 2012. PMID: 23785612
[16] Biolcati G et al. Long-term observational study of afamelanotide. Br J Dermatol. 2015. PMID: 25494545
[22] Raposinho PD et al. Melanotan-II reduces orexigenic effects of NPY. J Neuroendocrinol. 2003. PMID: 12535159
[23] Gilhooley E et al. Melanotan II User Experience. Dermatology. 2021. PMID: 34464955
[24] Bonchev A. Changes in Oral Mucosa Associated with Melanotan II. Life (Basel). 2026. PMID: 41752902
[25] Alsabbagh AY et al. Melanotan II nasal spray and oral mucosal malignant melanoma. Int J Oral Maxillofac Surg. 2025. PMID: 40210573
[26] Paiva L et al. Effect of Melanotan-II on Brain Fos and Oxytocin Neuronal Activity. J Neuroendocrinol. 2017. PMID: 28009464

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A drill-down index of the peer-reviewed melanotan record — Phase I trials, preclinical mechanism studies, and documented adverse events, cited to the source.