I've never had an issue going through security with my peptide (BPC-157), but I keep it in a discreet container that doesn’t draw much attention. I've heard they have been found on other people and confiscated, but no one has ever stopped me. I keep mine refrigerated when not using it, so I have been keeping it in the fridge at home before I travel and then just place it back in the refrigerator after my trip. You could probably carry a small cooler for it or something that keeps it cold and secure, but if you have a prescription label or doctor's note, that can help clarify things if TSA has questions.