Lansoprazole 15 mg Acid Reducer Capsules, 14 ct, QC99751 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 Ingredient in Prevacid. Treats frequent heartburn (occurs 2 or more days a week). May take 1 to 4 days for full effect. Delayed-release capsules.