collagenous colitis is a type of inflammatory bowel disease of the colon. on sigmoidoscopy or colonoscopy the bowel lining appears to be normal but microscopic examination of biopsies shows inflammation. the cause is unclear. the primary symptom of collagenous colitis is a non-bloody watery diarrhea but there also may be abdominal pain. the usual tests for diagnosing the cause of diarrhea are normal and the diagnosis is made with the microscopic exam of colonic biopsies. the disease may last for years and may subside with or without treatment. in some patients smoking cigarettes or taking medications such as nsaids may cause the collagenous colitis. the treatment of microscopic colitis has not been standardized because there have not been adequate large scale prospective placebo controlled treatment trials. the following strategies are safe and may relieve diarrhea in some patients: avoid nsaids and cigarettes. trial of lactose elimination (just to eliminate the possibility that intolerance to lactose in milk is aggravating the diarrhea). anti-diarrhea agents such as imodium or lomotil. bismuth subsalicylate such as pepto-bismol. 5-asa (mesalamine) compounds such as asacol pentasa or colazal. two studies have showed that budesonide (entocort) is effective in controlling diarrhea in more than 75% of the patients with collagenous colitis but the diarrhea tends to recur soon after stopping entocort. although data is lacking some doctors may consider using medications that potently suppress the immune system such as azathioprine and 6-mercaptopurine among patients with severe microscopic colitis that is unresponsive to other treatments.
what is collagenous colitis?