Rifaximin-treatment of Collagenous Colitis

The hypothesis of this study is that an altered gut microbiota is a contributory factor in initiating an inflammatory process in the colonic mucosa leading to collagenous colitis. The investigators suggest that treatment with budesonide reduces the inflammation without treating the underlying cause. In this trial the investigators will try to modullate gut microbiota by adding rifaximin. The aim of this study is to assess if 4 weeks treatment with rifaximin as a supplement to a standard course of budesonide against active CC can reduce the risk of relapse after treatment cessation.