There has been much interest in the use of antibiotics in IBS. There is circumstantial evidence that gut flora may play a role in the pathophysiology of IBS. Indeed, a 2-week course of rifaximin, a minimally absorbed antibiotic, at 550 mg three times a day was found to significantly improve symptoms of bloating, abdominal pain, and loose or watery stools among patients who had IBS without constipation [21]. This therapeutic approach for IBS was not given FDA approval. On the other hand, it may be premature to conclude that small intestinal bacterial overgrowth (SIBO) causes IBS [22]. To our knowledge there are no data in patients with coexisting IBS/IBD. However, SIBO can complicate IBD and this is more of a problem in Crohn’s than in UC. Although commonly used in clinical practice, commercially available breath tests have been criticized for being inaccurate at diagnosing SIBO [22]. Instead, they do accurately measure the speed of small bowel transit, which is often increased in IBS patients. We will occasionally give a short course of rifaximin for patients with IBS/UC with bloating, cramps, and diarrhea or if SIBO is suspected on clinical grounds. It is important to avoid repeated courses of certain antibiotics due to the high risk of C. difficile in UC patients. The role of the fecal microbiome in patients with UC and in patients with IBS is evolving. Perhaps a better understanding of the differences will lead to better disease-specific treatments [23].

Antispasmodics can be used as an adjunct for crampy abdominal pain or urgency, especially when symptoms occur immediately after eating. We have also found them to be useful for patients who have difficulty holding mesalamine enemas (instruct patient to take a dicyclomine or hyoscyamine tablet and a warm bath before administering the enema to help relax the spastic response to rectal and sigmoid distension). Antidiarrheals are helpful for controlling symptoms of diarrhea, although patients should be warned to take only as directed. Fiber supplements are also very good adjuncts. For diarrhea, fiber provides bulk to the stool and takes in water. For constipation or those with pellet-like or ribbonlike stools, fiber supplements taken with plenty of water help to regularize and give form to movements. For alternators who bounce between the two extremes, we have found that fiber drives patients’ bowel habits toward the middle. Care should be taken to avoid certain types of dietary or over-the-counter fiber formulations such as psyllium that worsen gassiness (Table 40.1). Our experience with using tricyclic antidepressants to treat functional gastrointestinal disorders suggests that they may provide important benefit in selected circumstances. We have also referred some patients for psychotherapy, which may help with coping.

Alternative therapies such as hypnosis, acupuncture, yoga, and other complementary approaches are often employed by our patients and should be encouraged when appropriate. However, patients should be cautioned to avoid herbal remedies, which may contain laxatives, nonsteroidal antiinflammatory drugs (NSAIDS), or psychotropic ingredients. Many such agents also have potent active pharmaceutical ingredients that may have toxic effects. Since most herbal remedies are not regulated and have not been rigorously evaluated in large-scale multicenter randomized placebo-controlled studies, the risks versus benefits of individual products are unknown, and there is at least theoretical potential that certain ingredients may worsen IBD.

Probiotics are generally considered to be complementary therapies. Although various probiotic formulations have been used for both IBS and IBD, evidence-based data in patients with IBS is lacking and there is no current consensus regarding efficacy. In IBD, there are some reasonable data in antibiotic-responsive pouchitis patients and in maintenance of moderate UC in remission. It is recognized that (a) patients often make use of probiotic supplements, (b) probiotics are not subject to FDA regulation, (c) most formulations appear to be safe, (d) many are costly and not covered by prescription benefit plans, and (e) further research is needed. This is an area of interest in both the IBS and IBD communities.

The following examples describe commonly encountered clinical situations and highlight how a thorough understanding of underlying pathophysiological mechanisms may aid in constructing a comprehensive treatment plan for patients with IBS/IBD.