Excellent Source of Calcium Upset Stomach Relief Antacid/Calcium Supplement Active Ingredient Calcium carbonate USP 750mg Uses Relieves sour stomach, acid indigestion, upset stomach associated with these symptoms or overindulgence in food and drink. Warnings Ask a doctor or a pharmacist before use if the child is presently taking a preion drug. Antacids may interact with certain prescription drugs. Questions? 1-800-897-7535