Irritable Bowel Syndrome or simply IBS is a condition of unknown cause that manifests as abdominal pain associated with either diarrhea or constipation. A minority of experts believe the diarrhea may result from overgrowth of bacteria in the small intestine. An oral antibiotic Xifaxan remains in the gut and may temporarily improve the condition but at a whopping cost of almost $40 a pill. At best it’s temporarily effective with multiple courses required as the drug fails to cure the condition.