Lansoprazole capsules are a proton pump inhibitor designed to reduce stomach acid production. They are commonly used to treat acid-related conditions such as gastroesophageal reflux disease (GERD), peptic ulcers, and Zollinger-Ellison syndrome. By decreasing the amount of acid in the stomach, these capsules help alleviate symptoms like heartburn and acid reflux while promoting the healing of the esophagus and stomach lining.