The mode of action of the product is physical and does not depend on absorption into the systemic circulation. On ingestion the product reacts rapidly with gastric acid to form a raft of Alginic acid gel having a near neutral pH and which floats on the stomach contents, quickly and effectively impeding gastro-esophageal reflux, for up to 4 hours. In severe cases the raft itself may be refluxed into the esophagus, in preference to the stomach contents, and exert a demulcent effect.