Neomycin and Rifaximin Plus Neomycin in Treating Methane Positive Constipation Predominant Irritable Bowel Syndrome

Inclusion Criteria: * Rome III positive IBS subjects (18-75 years of age) * Meet criteria for constipation predominant IBS symptoms including ≤ 3 complete spontaneous bowel movements per week with hard or lumpy stools. * Presence of detectable methane on single breath sample (≥ 3ppm). * If subjects are ≥ 50 years old, a colonoscopy had to have been completed within the past 5 years. Exclusion Criteria: * Subjects with history of intestinal surgery (except appendectomy or cholecystectomy) * Recent antibiotic use (within the last 30 days) * Subjects with known pelvic floor dysfunction * Pregnancy * Creatinine level \> 1.4 * Poorly controlled/uncontrolled significant medical condition that would interfere with study procedures * Subjects with hearing loss and/or tinnitus * History of bowel obstruction * History of celiac disease * History of inflammatory bowel disease * Cirrhosis * Diabetes