What is Omeprazole and How Does it Work?

Omeprazole is an active ingredient in over-the-counter (OTC) medications used to treat frequent heartburn caused by stomach acid in the swallowing tube, known as the esophagus.

Omeprazole is a Proton Pump Inhibitor (PPI), which is a class of drugs used to treat frequent heartburn symptoms by reducing the acid in the stomach that can cause heartburn. They work by binding to and blocking acid-producing pumps in the stomach.

Watch Prilosec OTC in Action

Omeprazole starts working within an hour of taking the first dose but may take 1-4 days for full effect. Within 24 hours, it reduces acid production by 67%.

Prilosec OTC and how it works

The active ingredient in Prilosec OTC is omeprazole delayed-release tablet 20mg (equivalent to 20.6mg omeprazole magnesium). As a PPI, Prilosec OTC treats frequent heartburn by blocking acid at the source, so you don’t get heartburn in the first place.*

Omeprazole benefits

The way the active ingredient omeprazole in Prilosec OTC works to fight heartburn makes it different from treatments such as acid controllers (also known as histamine blockers, or “H2s”) or antacids.

Acid controllers:

  • Partially reduce acid production by blocking only one of the signals that tell your body to produce acid

  • Provides heartburn relief in as little as 30 minutes

  • Heartburn relief lasts 12 hours


  • Provide immediate relief by neutralizing acid in the swallowing tube, known as the esophagus

  • Do not reduce acid production at its source, and actually can turn on acid production, which may lead to heartburn over and over again the same day

  • Heartburn relief lasts 1-3 hours

Prilosec OTC omeprazole delayed-release tablet 20mg (equivalent to 20.6mg omeprazole magnesium):

  • Blocks many of the stomach pumps that produce acid

  • Reduces the stomach acid that causes heartburn

  • Heartburn relief last for 24 hours with one pill a day*

*It’s possible while taking Prilosec OTC. Use as directed for 14 days to treat frequent heartburn. Do not take more than 14 days or more often than once every four months unless directed by a doctor. May take 1-4 days for full effect.

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