Loperamide is a standard treatment for diarrhea, and is available over the counter under the name, Imodium. Based on a few anecdotal reports, this drug is regarded as contraindicated in patients whose diarrheal disease is bacterial. But it is used widely, and generally without any diagnosis being established. We now propose to administer loperamide or placebo to patients with CDAD in order to determine whether the antidiarrheal drug reduces morbidity associated with the infection. We will monitor our patients closely both to observe potential benefits and/or adverse events.