Imodium (loperamide hydrochloride) is an antidiarrheal used to treat diarrhea. Imodium is also used to reduce the amount of stool in people who have an ileostomy (re-routing of the bowel through a surgical opening in the stomach). Imodium is available in generic form and over-the-counter (OTC). Common side effects of Imodium include. dizziness,