Rifaximin-treatment of Collagenous Colitis

Inclusion Criteria: * • Signed informed consent * Histological findings fulfill criteria for CC: * A subepithelial collagenous band \>10 μm in colonic biopsies * Increased count of inflammatory cells in lamina propria * Diagnostic biopsies are a maximum of two years old * A history of nonbloody, watery diarrhea for more than two weeks prior to screening in patients with recently diagnosed CC or a history of clinical relapse for more than a week in patients with known CC * Active disease: \> 3 stools/day or \>1 watery stool/day measured as a mean during a week prior to baseline Exclusion Criteria: * \- Significant findings at colonoscopy that could cause diarrhea (colonic diverticulosis and polyps \< 2 cm are not considered significant findings) * Biopsies more than two years old in a patient, who does not accept a new sigmoidoscopy * Untreated celiac disease * Positive stool cultures for pathogenic intestinal bacteria including Clostridium difficile * Suspected colitis induced by medication (diarrhea shortly after commencement of NSAID's, statins, SSRI or PPI) * Severe comorbidity (cardiovascular, renal, endocrine, neurologic, pulmonal or psychiatric) or history of cancer during the last 5 years * Abnormal liver biochemistry (ALAT or ALP \> 2,5 x upper limit), cirrhosis or portal hypertension * Pregnancy or lactation (assured by negative P-hCG at inclusion) * History of significant intestinal resection * Treatment with 5-ASA, Salazopyrin, immunemudulators (Azathioprine, 6-mercaptopurine or Methotrexate), biologic drugs (TNF-alfa-inhibitors), local or systemic glucocorticoids (except for Budesonide) within the last three month * Allergy or intolerance to Rifaximin (or similar antibiotics such as Rifampicin or Rifabutin) * Expectation of lack of cooperation or insufficient comprehension * Concomitant participation in an other clinical trial or participation within the last 30 days * Patients receiving Warfarin or Marcoumar (interaction with risk of uncontrolled INR-levels)