The active ingredient in Kirkland Signature Acid Controller Maximum Strength, 20 mg, an H2 Blocker. These partially block production of acid in the stomach cells by inhibiting histamine, a substance that stimulates the secretion of stomach acid. Over-the-counter and prescription H2 blockers relieve heartburn associated with acid indigestion and sour stomach and prevent meal-induced heartburn.

Two Bottles, 125 Tablets Each. Prevents and Relieves Heartburn and Indigestion. USP 20 mg - Acid Reducer, Compare to Maximum Strength Pepcid. Over-the-counter and prescription H2 blockers relieve heartburn associated with acid indigestion and sour stomach and prevent meal-induced heartburn. The active ingredient in Kirkland Signature Acid Controller Maximum Strength is Tablets, 20 mg, an H2 Blocker. These partially block production of acid in the stomach cells by inhibiting histamine, a substance that stimulates the secretion of stomach acid.