I took prescribed Losec (omeprazole) to control occasional heartburn for two years. After taking 20mg per day for 2 to 3 days I notice an occasional skipped heartbeat. I stop taking omeprazole and within 1-2 days this side-effect goes away. Two weeks later, I take omeprazole and go through the same cycle. I have thus experimented for two years before switching to zantac. There is no doubt in my mind that Losec causes temporary arrythmia and heart patients should be thus warned.