It might be that you need to change the timing of when you take your asprin, and other meds, relative to taking your antacids. Some antacids can reduce the absorption of medications. Have a look at the label/leaflet on the antacid.
Too little info to know for sure, but do take enteric aspirin with food. Aspirin does irritate the GI system. GERD can occur anyway. I have had it for years. I believe the GERD is related to the excess of inflammatory cytokines created by the JAK2 mutation. GERD an be quite damaging and may predispose you to more significant problems (hiatal hernia, Barret's esophagitis, esophageal cancer, etc.) Please do be sure to follow up on the GERD as it is treatable.
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