http://www.fda.gov/cder/drug/infopage/prilosecOTC/default.htm
Center for Drug Evaluation and Research, U.S. Food and Drug Administration
The Food and Drug Administration (FDA) has approved Prilosec OTC (omeprazole), the first over-the-counter treatment for frequent heartburn. Prilosec OTC is a delayed-release 20 mg tablet that must be taken before eating once a day, every day for 14 days. Prilosec OTC may take one to four days for full effect, although some consumers may get complete relief of symptoms within 24 hours.