But one bag has never been an issue for me in all my travels (usually I'm across three bags). But the 3.4 Oz or whatever is the crap shoot. Usually if I've "used some" from a larger toothpaste or 4 oz lotion bottle it's fine. But again I'll get checked every 6th time. So multiple bags is okay but I'd suggest sticking to the 3.4 oz max when you can.