Usually too much stomach acid as it is coming up that far to taste it. I was diagnosed with acid reflux and it kept getting worse and worse, and toward the end, I started tasting acid - yuk. After a few more months and a couple of days forgetting my prilosec I ended up in the hospital. Turns out is wasn't acid reflux - it was a gallbladder full of stones (over 30). After they removed it, the pain and everything was gone.------------------DeAnn "Dee"