Proton pump inhibitor (PPI) therapy is a miracle in the eyes of many people suffering from gastroesophageal reflux disease (acid reflux) also known as GERD. By blocking the enzyme in the wall of the stomach lining that produces acid, the fluid in the stomach contains less acid. This can help ease the symptoms of GERD and even allow the esophagus to heal, since even if the stomach juices back up into the esophagus, it's less irritating.