Within the US, should not be a problem. Just make sure the bottle is OUT and separate from other goodies, and NOT inside a bag. I have only had it questioned once, at LAX, where he told me I really wasn't allowed with it, but "just this time" (at which point you wonder, it is either safe, or it isn't). In any case, sometimes they pick up the bottle and look, or tell the screener, etc., but never has been a problem other than that one time.