Gaviscon Syrup contains Sodium Alginate 250 mg Sodium Bicarbonate 133.5 mg and Calcium Carbonate 80 mg. Sodium Alginate helps reduce gastric reflux by forming a rigid raft of alginic acid in the stomach. Sodium Bicarbonate is used as an antacid to treat heartburn indigestion and upset stomach. It works by reducing stomach acid. Calcium Carbonate is an antacid that lowers the amount of acid in the stomach thereby providing relief from heartburn acid indigestion and upset stomach. Gaviscon Syrup is used to treat gastritis (gastric reflux) oesophageal reflux acidity heart burn esophagitis indigestion and dyspepsia.