According to the International Foundation for Functional Gastrointestinal Disorders, the best antacid for reducing stomach acid is calcium carbonate, which is the primary ingredient in brands such as Tums and Titralac. Other antacids include sodium bicarbonate, aluminum hydroxide and magnesium hydroxide.
Commonly known as chalk, calcium carbonate can completely neutralize stomach acid, but is not recommended for long term use as it can potentially lead to health problems. The IFFGD states that the recommended dose of calcium carbonate should not exceed 3 grams per day.
Magnesium hydroxide, also known as milk of magnesia, would potentially be the best antacid, as it is both effective and safe for long term use. However, milk of magnesia usually causes diarrhea, so it is more commonly used as a laxative. Still, many antacid tablets cancel out the laxative the effects by combining magnesium hydroxide with aluminum hydroxide, an antacid with constipating effects. However, these tablets are less effective, as aluminum hydroxide is a much weaker antacid.
Sodium bicarbonate, also known as baking soda, is a fairly weak, short lasting antacid found in Alka-Seltzer and other products. It can be a somewhat effective home remedy, but is unlikely to be recommended by a doctor due to its high sodium content.