Sodium alginate, Sodium bicarbonate, Calcium carbonate Gaviscon Double Action Mint Flavour Chewable Tablets bring long lasting relief from the pain and discomfort of heartburn and acid indigestion. They get to work in two different ways: 1) Neutralising excess stomach acid to relieve pain and discomfort 2) Forming a protective barrier over the stomach contents to soothe the burning pain in your chest What are these tablets? Each chewable tablet contains 250mg sodium alginate, 106.5mg sodium bicarbonate and 187.5mg calcium carbonate as the active ingredients. The tablets do not contain sugar or gluten. You can take this product if you are pregnant or breast feeding.. Heartburn & indigestion. Fast effective relief. Gaviscon.