Side effects of melanotan reported in medical journals
Important: Melanotan II is not approved for human use in the US, UK, EU or Australia. This page does not give dosing instructions and is not medical advice. If you have a changing mole or any symptom described here, see a doctor.
Because melanotan II is not an approved medicine, there are no large safety trials of the products people actually buy. What we know comes mostly from case reports and reviews written by doctors who treated people after problems. Here are some of the documented reports.
Published reports
Priapism (a painful erection that will not go away). A UK case described a man who came to the emergency department with low-flow priapism after injecting melanotan. He needed emergency treatment and had not recovered erectile function at four weeks (Dreyer et al., BMJ Case Reports, 2019 (PubMed 30796078)). Priapism is a medical emergency.
Kidney problems. A 2020 case report and literature review described a kidney infarction (loss of blood flow to part of a kidney) most likely attributed to melanotan II, and noted earlier reports of rhabdomyolysis and kidney failure (Peters et al., CEN Case Reports, 2020 (PubMed 31953620)).
Contamination and labeling risks. A 2026 review on unregulated "biohacking" peptides lists melanotan II among products without established human safety data and highlights risks such as contamination, impurities and inaccurate dosing (Moiz et al., Missouri Medicine, 2026 (PubMed 42757290)).
Seek urgent care if
You have an erection lasting more than 4 hours, chest pain, severe headache, dark urine with muscle pain, or sudden flank (side/back) pain. Tell the medical team exactly what you used.