Pantoprazole is a prescription drug used as a short-term treatment for gastroesophageal reflux disease (GERD). It's part of a class of medications known as proton-pump inhibitors (PPIs) and is marketed under the brand name Protonix. GERD is a condition in which the backward flow of acid from the stomach causes heartburn and sometimes injury of the esophagus. PPIs such as pantoprazole work by blocking the production of acid made in the stomach. Pantoprazole may also be used for a longer period of time for maintenance or healing of erosive esophagitis, and to treat conditions where the stomach produces too much acid, such as Zollinger-Ellison syndrome.