Rennie is an antacid that relieves the pain and discomfort of heartburn and indigestion by neutralising excess acidity in the stomach. Rennie is specifically formulated to provide fast, effective temporary relief from heartburn and indigestion, and is used by millions of people around the world each year. Rennie tablets are spearmint flavoured and contain the naturally occurring active ingredients calcium carbonate and magnesium carbonate. Unlike some antacids, Rennie is aluminum free and does not cause constipation.Rennie is the antacid of choice for heartburn in pregnancy. Up to 80% of all pregnant women experience heartburn and indigestion during pregnancy. Rennie relieves symptoms fast and provides a rich source of calcium to strengthen mother's and baby's bones and teeth. Each Rennie tablet provides 25% of the daily calcium requirement for pregnant women. Each tablet contains: calcium carbonate 680 mg and Magnesium carbonate Heavy 80 mg Rennie Tab X 24.