I take a FULL course of Flagyl if and only if I get to a point where no matter how "cleanly" I eat (i.e., avoiding the stuff that I know causes me gas), I still get blown up and uncomfortable by mid-afternoon. For about a year and a half (2013-2014), I had to do it about every 3-4 months, but I've been good for most of a year now - around the time I started using PDU in the AM and Culturelle in the PM, rather than just two doses of PDU.
I don't take it "for a trip" and I don't take a dose here and there. I think that's a recipe for disaster. Having said that, I HAVE heard of people taking a low dose prophylactically when they could not get relief any other way - but I think that is dangerous and just asking for an intractable case of antibiotic-resistant C. diff.
