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 of 10 people would use Gaviscon Double Action again (based on a survey of 45 heartburn and indigestion sufferers compared to control. For over 40 years, Gaviscon has helped to provide millions of people with fast, effective heartburn and indigestion relief.