I was taking prevacid for 6 years with no problems, then the insurance insisted I switch to omeprazole and after 2 weeks I developed severe upper abdominal pains, almost like a heart attack, with nausea, vomiting, weakness and cold sweats. It was a trip to the hospital and my primary care physician who swore that it could not be the Omeprazole and to continue. After the 2nd bout a week later I insisted that it was the meds and wanted something different. As I started taking something different I started feeling better after a couple of days and felt like I was over the problems after about 10 days and have had no problems since. Just the $7,000 medical bills.