Imodium is used against acute or chronic diarrhea. Acute diarrhea starts suddenly and is usually gone within a week. Chronic diarrhea is prolonged. Imodium is used to treat the diarrhea itself. It does not address the cause of the diarrhea. If the cause of the diarrhea is known, this should be treated. Imodium capsules contain loperamide hydrochloride (2 mg per capsule). This is a substance which reduces too strong propulsive movements of the intestine. Imodium works only there where it is needed, in the colon. Imodium stops diarrhea usually within hours. Always read the leaflet before the use of medication.