Antacid Extra-Strength Chewable Tablets, Asst Fruit Flavors, 96 ct, QC94810 Sale! This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Compare to the Active Ingredients in Tums Extra Strength. An antacid that relieves heartburn, sour stomach, acid indigestion, and upset stomachs. Calcium Supplement: As a daily source of extra calcium.