Ok I have been taking protonix 40 mg once a day for a couple months, it was working fine til the last week or so, I went ahead and took it twice a day and a friend told me I should never double dose this stuff, but no one can tell me WHY NOT! What will happen if I do continue to do it for breakthrough heartburn til I see my Dr nevt week?? I can't afford to let it slip, I have Barrett's with no cell change and want to keep it from getting to that point. I've tried previced, prilosic aciphex and lots of otc and nothing works for very long. I'm going to get my Dr to give me Nexium to see how it works. So til then why can't I double dose? Even double dose doesn't work that great! Can anyone tell me the hazards of taking two pills a day instead on one??