Gaviscon Double Action Liquids Aniseed 250mlGets to Work Instantly 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 survey of 45 heartburn and indigestion sufferers compared to control. Lasts up To 2 X Longer than Antacids Unlike antacids, Gaviscon Double Action forms a raft, or layer, on the top of your stomach contents and to help keep stomach acid