Christine, thanks for your explanation. It helps tremendously.I posted my question because I often wonder if I really have GERD. My main symptom is nausea, especially when lying down and upon waking in the morning. After having an upper endoscopy and biopsies for IBD and Celiac disease come back negative, my GI told me I have "acid reflux" and prescribed Losec (omeprazole)(20mg).At first, the Losec made my nausea worse. Then it got a little better, but was still pretty bad. So I was given Motilium (domperidone) to take in addition to the Losec. It really helped a lot. Unfortunately, my prolactin levels went way too high, so I had to stop taking it. Of course, the nausea came back, so I was told to take 40mg of Losec. That seemed to work, but right now I'm back down to 20mg. My GI wants me try to wean myself off the Losec. My problem is, the nausea is getting bad again.I' really not sure what to do. Although I had an upper endoscopy done, I never had the 24-hour pH monitoring test done. My understanding is pH test is the only one that will definitively diagnose GERD. Is this true? It seems my GI's approach is more symptomatic: antacids reduce the symptoms, therefore, excess acid is the problem. I feel the problem is more likely one of motility since the Motilium helped me the most.When I saw my family doctor (my GI is on maternity leave at the moment), she suggested switching to another antacid. I'm just not comfortable taking prescription antacids all the time, considering we don't really know a whole lot about their safety. (BTW, I've been taking Losec for 2 years now.)Does anyone have any thoughts on any of the above or any suggestions? I would really appreciate any input any of you might have. Thanks.