I have been taking four grams of cholestyramine every day for two years. My doctor prescribed it for me because I was experiencing diarrhea. Since I started taking it, I have gained at least 25 pounds. This medication is for cholesterol, but my cholesterol count is very good. Is there something else I could take for my diarrhea?

S.

Most of episodes of diarrhea last only a few days and are caused by acute bacterial or viral infections. However, in some cases, diarrhea persists longer than a few weeks. Causes of chronic diarrhea include irritable bowel syndrome, Crohn's disease, parasites, metabolic disorders, side effects of medications and certain rare tumors.

Many people with chronic diarrhea will receive therapies aimed at treating the root cause. In other cases, therapy to relieve the diarrheal symptoms may be given. For example, in irritable bowel syndrome, often an increase in dietary fiber serves to bulk up the stool and increase its consistency, thus improving the symptom of diarrhea.

Questran (cholestyramine) is a medication used in certain types of diarrhea in which bile acids are thought to play a role. Bile acids are normally made in the liver and delivered to the small intestine during meals to aid in the digestion of fats. Between meals, bile acids are stored and concentrated in the gallbladder. In patients who have had their gallbladders removed, there is no storage space for bile between meals, and it is constantly being delivered to the intestine. Similarly, in patients with disease of the small intestine (such as Crohn's), the bile acids cannot be reabsorbed and enter the large intestine (colon) in large amounts. It is thought that bile acids injure the lining of the colon, causing diarrhea as a result. This mechanism could explain the diarrhea that is seen in patients with Crohn's and in some patients who have had their gallbladders removed. Cholestyramine binds bile acids, keeping them from reaching the colon and thereby stopping bile-acid-induced diarrhea.

In your specific situation, the weight gain may be the result of the cholestyramine's effectiveness in treating your diarrhea. Alternatively, you may have gained weight because of other reasons, including dietary changes.

It is impossible for me to determine what originally caused your diarrhea without examining you personally and knowing your full history and the results of your diagnostic tests. So, I recommend that you discuss your problem with your treating doctor. He would be in the best position to determine whether you need to continue the cholestyramine or whether another medication might be more helpful.