An antacid is a type of medication that helps neutralize stomach acid, providing relief from heartburn, indigestion, and upset stomach. These over-the-counter products typically contain ingredients like magnesium hydroxide, aluminum hydroxide, or calcium carbonate, which work by raising the pH level in the stomach. Antacids are usually taken in liquid or tablet form and can act quickly to alleviate discomfort. While they are effective for occasional use, frequent reliance on antacids may indicate a more serious condition, and it is advisable to consult a healthcare professional if symptoms persist.