Zantac 75® is different than antacids that neutralize the acid already in your stomach. It reduces the production of stomach acid. Zantac 75® can be used for: relief of heartburn associated with acid indigestion and sour stomach. prevention of heartburn associated with acid indigestion and sour stomach brought on by certain foods and beverages. Free of sugar, lactose, gluten, sodium and all animal by-products.