TUMS Chewable Antacid Tablets go to work in seconds, so you can forget your heartburn and get back to the moments that matter. TUMS extra strength antacid chewable tablets contain 50 percent more acid neutralizing power than regular strength TUMS, for fast acting relief. Each TUMS chewable antacid contains 750 mg calcium carbonate to quickly and effectively provide heartburn relief, sour stomach relief, acid indigestion relief and relief of upset stomach associated with these symptoms. TUMS heartburn medicine neutralizes acid on contact, giving you fast relief.