As many as one in five Americans, or 55 million people, suffer with the abdominal discomfort associated with irritable bowel syndrome (IBS), according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Symptoms vary from patient to patient but typically include abdominal pain and discomfort with changes in bowel function-either predominantly diarrhea (IBS-d) or constipation (IBS-c). Some patients, however, experience a mixed form (IBS-m), with alternating diarrhea and constipation. Currently there exist few therapies for treating the condition; however, several entities in development look promising.