If Cdiff returns after you complete the meds, I would suggest you request Dificid. I took Flagyl with my first Cdiff infection, Vanco for 10 days with the second, Vanco pulse and taper for 5 or 6 weeks with the third bout, and FINALLY with the 4th bout in six months, they prescribed Dificid which worked. It's expensive and my insurance wouldn't approve until after trying Vancomycin which is much cheaper. But I was desperate and had decided if Dificid didn't work, I was having a fecal transplant.