Gaviscon Double Action Tablets Gaviscon Double Action Tablets get to work instantly to effectively relieve heartburn & indigestion & last up to 2x longer than antacids. The powerful formula contains two antacids & an alginate to quickly neutralise excess stomach acid to relieve pain & discomfort & to form a protective barrier over the contents of the stomach to help prevent acid coming back up into the oesophagus (food pipe). Gaviscon Double Action Tablets are suitable for use during pregnancy & breastfeeding. How Gaviscon Double Action works (video).