Overindulgence can lead to some pretty significant indigestion: Keep the antacid Mylanta on hand to relieve heartburn fast. In each 10 mL dose, there is 1200 milligrams of calcium carbonate; 270 milligrams of magnesium hydroxide; and 80 milligrams of simethicone. Works on contact with no chalky taste. Bottle contains 12 ounces of chocolate mint flavor liquid antacid.