How long does a c-diff infection last?

Long if not treated: C. Difficile can cause a prolonged severe colitis if it is not treated. If treated it usually starts to improve 3-4 days into the 10-14 day treatment course. Relapses occur in 25% of cases. These relapses require re-treatment and can continue to recur requiring prolonged pulse/taper vancomycin treatment and even fecal transplant therapy for cure.