Proton pump inhibitors (PPIs) are a group of prescription medications that prevent the release of acid in the stomach and intestines. They act by blocking the hydrogen-potassium adenosine triphosphatase enzyme system (or "proton pump") from the gastric (parietal) cell. Doctors prescribe PPIs to treat people with acid reflux, duodenal and gastric ulcers, and excess stomach acid (Zollinger-Ellison Syndrome).

Some common PPIs are:

PPIs are very effective and generally heal about 80 to 90 percent of ulcer patients and eliminate the pain for 60 to 70 percent of reflux disease patients. They are more effective for reflux disease than H2-receptor blockers (Axid, Tagamet, Zantac). PPIs are very expensive, however, and doctors often prescribe PPIs only if H2-receptor blockers don't work.