Gaviscon Liquid Aniseed 500mL Gaviscon Liquid contains sodium alginate, which is naturally derived. It is classed as an “alginate” which means that it forms a “protective layer” over the stomach contents which helps to prevent acid coming back up into the oesophagus (food pipe). As such, it is fast acting and has a soothing effect, lasting up to four hours. It is effective at treating the classic symptoms of heartburn (a burning pain in the chest and mild acid regurgitation). CAUTION: Always read the label. Use only as directed. If symptoms persist see your Health Care Professional. Contain calcium carbonate & sodium bicarbonate.