Efficacy of Rifaximin With NAC in IBS-D

Inclusion Criteria: 1. Male or non-pregnant, non-lactating female patients ≥ 18 years of age 2. Diagnosed with IBS confirmed by the Rome IV criteria, with associated symptoms of diarrhea as noted below in 4(b). 3. Do not have adequate relief of IBS symptoms of abdominal pain, stool consistency or stool frequency 4. Have daily IBS symptom scores during screening as below: 1. Weekly average score of worst daily abdominal pain \>3.0 on a 0-10 point scale 2. At least one stool with a consistency of Type 6 or 7 on the Bristol Exclusion Criteria: 1. Present with the following symptoms of IBS with constipation: 1. Less than 3 bowel movements a week, 2. Hard or lumpy stools, and 3. Excessive straining during a bowel movement. 2. History of inflammatory bowel disease, celiac disease, GI surgery (except cholecystectomy and/or appendectomy) 3. Evidence of active duodenal ulcer, gastric ulcer, diverticulitis, or active infectious gastroenteritis 4. Current diagnosis of asthma 5. Current user of NAC and/or rifaximin 6. Systemic antibiotic use in the last month 7. Not currently on a prokinetic drug 8. A significant medical condition including but not limited to hepatic, uncontrolled diabetes, renal, cardiovascular, pulmonary, uncontrolled thyroid disease. or psychiatric disease, which in the opinion of investigator precludes study participation