Subjects must be 18 years old and older, have diarrhea and microscopic colitis. Subjects will be excluded if they have unsuccessful treatment or side effects to 5-ASA drugs, oral corticosteroids, or salicylate. and antibiotics, mesalamine, bismuth or steroid use in the last two weeks. Subjects may not be on anticholinergics, cholestyramine, digoxin. Pregnant or nursing females are excluded. They can't have other untreated diarrheal conditions.