I took Zantac off and on for years, but after a recent upper endoscopy my GI dr. prescribed Omeprazole (Prilosec). When I went to the pharmacy to have the prescription filled, I found that it wasn't on the insurance formulary and they were going to charge me $60.00. The pharmacist recommended that I take the Prilosec OTC (for $27) and that the only difference was that the Prilosec OTC has magnesium in it. Well, I also have IBS-D and was worried that the magnesium might make those problems worse! So, I had the prescription for Omeprazole filled. At my follow up visit with the GI, he didn't know that Prilosec OTC has magnesium in it, so obviously didn't know how much was in it, and just said I'd have to give it a try to find out if it would be a problem for me. So, I'm wondering if anyone out there with IBS-D as well as GERD has any experience with this?