Tums is an antacid used to relieve heartburn, sour stomach, acid indigestion, and upset stomach associated with these symptoms. The active ingredient in Tums is calcium carbonate, which is a naturally mined product. Calcium carbonate is the primary active ingredient in all Tums products and goes to work in seconds to neutralize stomach acid and relieve heartburn. Most antacids contain at least one of these key ingredients: calcium carbonate, magnesium hydroxide, aluminum hydroxide, and/or sodium bicarbonate. Tums, Alka-Seltzer, and Rolaids are brands of antacids made of calcium carbonate. Tums come in a variety of flavors and chews, which makes taking them easier. The dosing of Tums varies depending on the product, but the recommended dose is usually 2-3 tablets as symptoms occur, or as directed by a healthcare provider. Pregnant females should not take more than 4-6 tablets per day, depending on the product. Calcium carbonate is also used as a calcium supplement, and the recommended daily allowance (RDA) for calcium is 1,000 mg elemental calcium daily for males and females aged 19-50 years.