irritable bowel syndrome (IBS) [L, irritare, to tease; OFr, boel + Gk, syn, together, dromos, course] , abnormally increased motility of the small and large intestines, of unknown origins. Most of those affected are young adults who complain of diarrhea and, occasionally, pain in the lower abdomen. The pain is usually relieved by passing flatus or stool. In diagnosing irritable bowel syndrome, other more serious conditions, such as dysentery, lactose intolerance, and the inflammatory bowel diseases, must be ruled out. Because there is no organic disease present in irritable bowel syndrome, no specific treatment is necessary. Many persons benefit from the use of bulk-producing agents in the diet because bulk tends to stabilize the water content of the stool. Antidiarrheal drugs are helpful in decreasing the frequency of stool. Although this is a functional disorder, patients experience pain and discomfort and need emotional support. Mild tranquilizers or antidepressants are sometimes given to relieve anxiety or depression. Also called functional bowel syndrome, mucous colitis, spastic colon.
