Rennie Peppermint neutralises 99% of stomach acid gets to work in 60 seconds to relieve the symptoms of heartburn and indigestion. Two naturally occurring antiacids, Calcium Carbonate and Magnesium Carbonate, get to work quickly to neutralise excess stomach acid but turning it into water and other natural substances. Calcium Carbonate acts in the oesophagus as well as the stomach, and both antacids are then eliminated by your body. Key features of Rennie Peppermint Peppermint flavour chewable tablets Relieve the symptoms of heartburn and indigestion Neutralises stomach acid by turning it into water and other natural substances With Calcium Carbonate and Magnesium Carbonate Acts in the oesophagus as well as the stomach. Please note that results may vary.