With one Prilosec OTC pill in the morning block your heartburn all day and all night.* Heartburn happens when stomach acid refluxes into the esophagus. Prilosec OTC s delayed-release formula helps it pass through the tough stomach acid preventing excess acid production to block frequent heartburn.* Some other heartburn relief treatments only neutralize the stomach acid after it s already been produced and provide shorter relief (less than 24 hours). Prilosec OTC is the #1 Doctor and Gastroenterologist recommended frequent heartburn medicine for 15 straight years.^ * It s possible while taking Prilosec OTC. Proton Pump Inhibitors like Prilosec OTC work differently to treat frequent heartburn for 14 days. Compared to how antacids and H2 blockers work for heartburn. Use all heartburn medications as directed. Do not take for more than 14 days or more often than every 4 months unless directed by a doctor. Not for immediate relief. ^IQVIA ProVoice Survey Jan 2005 - Mar 2020.