Prevacid, also known as lansoprazole belongs, to a class of drugs called proton pump inhibitors. This medication works by reducing the acid that is produced in the stomach. Generic Prevacid is an ulcer medication that help treat erosive esophagitis and Zollinger-Ellison syndrome. However it is important to note that this medication is not meant to be used for the immediate relief in heart burn or stomach acidity problem. Your doctor may advise you to buy Prevacid for health ailments that are not listed here.