The treatment of IBS and IBD are markedly different. Since IBD is an inflammatory disorder, anti-inflammatory agents such as the mesalamine products (Asacol and Pentasa), steroids, (Prednisone and Entocort), immunosuppressive agents (6-MP, Imuran and Methotrexate) and biologics (Remicade and Humira) are used. Patients with IBS on the other hand, are treated with medications that treat diarrhea (Immodium and Lomotil), constipation (laxatives such as Miralax) and abdominal cramping (antispasmodics Bentyl and Levbid).
While some cases of IBD with minimal pathology can be difficult to distinguish from IBS, in general, a good history is all one needs. If you have, however, been diagnosed with IBS and are not responding to medical treatment, check with your doctor to insure that IBD has been ruled out.