I've been using Melanotan 2 for several years. The first few years, I tested numerous suppliers, and always responded to the peptide. Some more potent than others. I've now tested a good 12 different suppliers, and I just plain don't respond like I used to. No flushing, no erections, no facial hair darkening, no appetite suppression, nothing.
I even tried taking 3 months off without MT2. I'm now about a week into dosing, and have zero side effects.
I think it's time to seriously consider the possibility that our bodies become tolerant to the peptide after some time.
Does anyone have anything else to add?