Melanotan 2 (MT-2) is an experimental peptide that stimulates melanin production and has not been approved by regulatory agencies like the FDA. Users report both common and serious side effects. Common effects include nausea, facial flushing, fatigue, and headaches, typically occurring during initial doses. Many users experience involuntary penile erections, which some seek the compound for but can be uncomfortable or persistent. More serious potential side effects include darkening of existing moles and potential skin cancer risk, though long-term safety data in humans is limited. Cardiovascular concerns have been raised, including effects on blood pressure and heart rate. Some users report mood changes, dizziness, and appetite suppression. Because MT-2 is unregulated and typically sourced from underground laboratories, additional risks stem from uncertain purity, contamination, and inconsistent dosing. The compound was originally developed as a research chemical and abandoned before clinical trials were completed, meaning the full spectrum of side effects—particularly long-term consequences—remains unknown. Medical professionals generally advise against its use due to insufficient safety data, lack of regulatory approval, and the unknown risks associated with stimulating melanin production systemically. Anyone considering use should understand they are essentially participating in an uncontrolled experiment with their own health.