<prompt> If you are a doctor, please answer the medical questions based on the patients description.I ve been on omeprazole for a dozen years reflux and developed microscopic colitis about two years ago. No pain with the colitis, but very soft stool and occasionally diarrhea. Nothing has helped: I ve tried Entocort, laiada, bismuth, probiotics, lactose free diet for about a month. Because the omeprazole may contribute to the colitis, I ve been urged to substitute pantoperazole or lanoperazole for the omeprazole. I ve been told that the former may be less likely to trigger the colitis than the omeprazole. Any suggestions?  <response>: Hi, Based on the history colitis seems to be due an important side effect of proton pump inhibitor omeprazole. Colitis seems to be due to bacterial infection which occurs due to suppression stomach acid production by proton pump inhibitors. All the proton pump inhibitors are known to cause colitis or diarrhea. I suggest you to take and H2-receptor blocker like famotidine for your reflux disease. Hope I have answered your question. Let me know if I can assist you further. 