Used primarily to reduce stomach acid production, this compound is employed in the treatment of conditions such as peptic ulcers, gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome. It works by blocking histamine H2 receptors in the stomach, thereby decreasing acid secretion. It has also been used short-term to relieve symptoms of heartburn and acid indigestion. Due to concerns over impurity formation, its use has declined in many countries, with alternatives now preferred.