Hi, There are studies monitoring a chronic use of Prilosec for as long as a year, but not longer than this period of time. You will need to check liver enzymes to make sure nothing s wrong with your enzymes. I would try to understand better the cause of your chronic high gastric acid level. It may be a metabolic disorder, such as Zollinger-Ellison Syndrome, where there is a high level oglf gastrin produced, resulting in a high gastric acid level. I would recommend a measurement of both levels, gastrin and acid output to rule out this condition. Next, I would recommend a visit with a therapist or psychiatrist. Most of times conditions such as depression, anxiety, stress, panic or different phobias are associated with high acid output, resulting in a chronic gastritis/GERD. Please check for any change in yourstool color, cause it can indicate a gastric hemorrhage due to a gastric/duodenal ulcer. I hope I have helped you to understand better your condition. Wish you good health.