Hi Bearcat, Please take a copy of the theory with you to your autonomic docs, but I can tell you that they will laugh OUT LOUD when you mention Diamox. It goes against everything we’ve done to treat POTS in the past. We had always tried to increase our blood volume, and Diamox is a mild diuretic (not the major reason we use it — we use it to reduce the production of CSF which we can’t drain), but in the short run, it won’t help OI (orthostatic intolerance). The idea is to take the pressure off of the brain, allow it to float again, and reduce the pressure on the brainstem from the overly full cerebromedullary cisterns. We are hitting the source of the POTS, not the symptoms, with the hope that we can eliminate the POTS. But the treatment for mast cell disease is also a critical component for most of us. Some doctors even believe that ALL POTS is secondary to mast cell disease. I think it is a bit more complicated than that, but it is a component, certainly. Finally, the Diamox is a carbonic anhydrase inhibitor and as such, it will cause some acidity (think of it as a side effect). If you are too acidic (CO2 levels below 22), it stops working. So taking a PPI to reduce acidity only helps us. With mast cell disease we also tend to have WAY too much stomach acid, so the PPI (and/or Zantac) is doubly important. Does that make more sense? Thanks!