Omeprazole 20 mg Acid Reducer Tablets, 14 ct, QC99778 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 Prilosec OTC. Treats frequent heartburn (occurs 2 or more days a week). Can take 1 to 4 days for full effect. One 14-day course of treatment.