Antacids describe several classes of drugs that prevent stomach acid from building up in the stomach. They are used by a variety of patients with ailments ranging from heartburn to acid reflux disease to gastric ulcers.
They generally fall into these types:
Bases - these are substances with a high alkalai content, one of the most common being baking soda. These neutralize existing acid through a chemical reaction where the acid combines with the base to form water and salt.
Proton-pump inhibitors - These drugs restrict the ability of the stomach to produce acid by slowing down the reaction that strips protons from electrons to create the acid.