This is a generic product sold under its chemical name "lansoprazole".
Prevacid blocks the production of stomach acid. It is prescribed for the short-term treatment (up to 4 weeks) of duodenal ulcers, (ulcers near the exit from the stomach). It is also used for up to 8 weeks in the treatment of stomach ulcers, gastroesophageal reflux disease (backflow of acid into the canal to the stomach), and a condition called erosive esophagitis (severe inflammation of the canal).
For additional information on Prevacid, click here.