Gaviscon Double Action brings long lasting relief from the pain and discomfort of heartburn and acid indigestion. Gaviscon Double Action’s formulation gets to work in seconds to create a protective barrier that lasts up to 4 hours; In fact, 9 out 10 people would use Gaviscon Double Action again (based on a 2012 survey of 45 heartburn and indigestion sufferers compared to control. Unlike antacids, Gaviscon Double Action forms a raft, or layer, on the top of your stomach contents and helps keep stomach acid in your stomach, where it belongs.