Clinical Research Directory

Antihistamines in the Treatment of Irritable Bowel Syndrome With Diarrhea

Irritable bowel syndrome is a functional disorder of the gastrointestinal tract diagnosed with the Rome criteria. The Rome IV criteria are based on abdominal pain symptoms and stool habits including stool frequency and stool forms \[1\]. They define 3 main subtypes based on symptoms: 1) IBS with diarrhea; 2) IBS with constipation: and 3) mixed symptoms of constipation and diarrhea. The IBS with diarrhea (IBS-D) subtype has the highest prevalence. Currently, treatment of IBS-D includes antidiarrheals, bile acid sequestrants, antispasmodics, tricyclic antidepressants, and FODMAP diet. However, many patients are intolerant or unresponsive to the above treatments. Outside of IBS, chronic diarrhea affects about 5% of adults. We have described a syndrome in a subset of IBS patients presenting with post prandial diarrhea, flushing and dermatographia whose symptoms are prevented by pre-treatment with combined H1 and H2 antihistamines \[2\]. However, the prevalence of this syndrome among the IBS + D patients is not known nor have the clinical characteristics or predictors of antihistamine responsive IBS + D been defined.