Histamine-2 receptor antagonists, also known as H2 blockers, are a class of medications that reduce the production of stomach acid. They work by blocking the action of histamine on the H2 receptors in the stomach lining, which helps to decrease acid secretion. This can be beneficial for conditions like gastroesophageal reflux disease (GERD) and peptic ulcers. Common examples of H2 blockers include ranitidine, famotidine, and cimetidine. These medications are typically available over-the-counter and are used to relieve symptoms such as heartburn and indigestion. While generally safe, they can have side effects and may interact with other medications, so it's important to consult a healthcare provider before use.