Rennie Spearmint is an antacid tablet that neutralises excess stomach acid to relieve the symptoms of heartburn and indigestion. Rennie Spearmint pr s fast and effective relief from heartburn and indigestion in a handy spearmint flavoured tablet. It contains magnesium carbonate and calcium carbonate, which work together to create an antacid that neutralize stomach acid. The effective formula also helps to relieve acid indigestion, dyspepsia, hyperacidity, gastritis, nervous indigestion, flatulence, upset stomach, indigestion during pregnancy and biliousness.