Zantac Zantac 75 mg Acid Reducer Zantac 75 is used for the relief of heartburn associated with acid indigestion and sour stomach. Zantac 75 is also used for prevention of heartburn associated with acid indigestion and sour stomach brought on by certain foods and beverages. The active ingredient is ranitidine hydrochloride (84 mg per tablet, equivalent to 75 mg ranitidine). Each bottle contains 60 tablets. Click on the smaller image to read the label for more information.