<<Disclaimer: Verify this information before applying it to your situation.>> Just my personal experience: Here is the experience I've had with antacids and/or anti-acids. For years I would intermittently get this queasy clammy feeling, often with that foggy mental state, that would last for days, sometimes as much as two or three weeks. It was usually worse an hour or two after eating, especially after any gluten (before I was diagnosed as celiac and ate GF). It was definitely an unpleasant "sinking" feeling. For a long time I thought I was having an insulin reaction to what I'd eaten. I also got this feeling after going too long without eating, and I thought perhaps I was hypoglycemic. Sometimes I thought I had the flu, and it sometimes felt like the time I had diverticulitis. Finally my internist told me it was just acid reaction, and he gave me a prescription for Prevacid. He said he prescribed Prevacid because it did not generate an acid rebound (I don't if Prilosec does or not). At first I thought he must be wrong, but when I followed his advice I learned to handle the problem well. The way I handle this now is that when I get acid reflux, either heartburn or the chest pain, I take two Zantac 75s. As my internist explained it, a small gluten accident, heavy fat or alcohol can cause this problem. Gluten causes gas, and the pressure of that gas often forces acid and the contents of the stomach, under pressure, to back up into the esophagus - hence heartburn. The fat and alcohol, especially when taken in the evening, relax the sphincter to the esophagus allowing more acid to pour back into the esophagus; and this causes the sphincter to cramp, causing pain, as any muscle cramp can cause. This pain is often worse when I lie down, and could easily be mistaken for a heart attack. It can even cause pain in the left arm and the left jaw like a heart attack. A hiatal hernia can also cause this, because there is a sympathetic nerve from the diaphram, which is penetrated in a hiatal hernia, to the heart; so it can cause similar symptoms. So I have learned that when I expect to splurge and ingest fat (like barbeque or a prime rib) or alcohol in the evening or late afternoon I take two Zantac before I begin. Then about an hour before bedtime I take two more Zantac. This usually stops any temporary problem. But Zantac causes a rebound effect: when you take it to stop the acid production over a period of time it will cause your system to produce more acid to counteract the effects of the Zantac. This is when I get the acid attack that causes that crappy queasy clammy sensation, and can also cause some intestinal pain. When this happens I take a Prevacid each day for three days to a week (while also avoiding alcohol and most fat), and this seems to reset my acid clock (or whatever you call it) and interrupts the process. Usually that sensation will be a little better by the end of the first day, and mostly gone after three. After it stops completely I can stop taking the Prevacid till I have that problem again. -vance