TUMS Chewable Antacid Tablets go to work in seconds, so you can forget your heartburn and get back to the moments that matter. These ultra-strength antacid chewable tablets contain double the acid neutralizing power per tablet of regular strength TUMS for fast-acting relief. TUMS chewable antacid tablets contain the active ingredient calcium carbonate, which is naturally sourced, to quickly and effectively fight heartburn and relieve sour stomach, acid indigestion, and upset stomach associated with these symptoms. TUMS heartburn medicine neutralizes acid on contact, giving you fast heartburn relief.