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Is Nexium 24HR an Antacid?

Woman taking pill in shadow

Nexium 24HR is not an antacid.

It’s a medicine known as a proton pump inhibitor (PPI). Nexium 24HR is an acid reducer that provides longer heartburn relief than over-the-counter (OTC) antacids.

It also provides longer relief than histamine blocker (h2 blocker) treatments.

Such protection power makes Nexium 24HR an effective treatment for frequent heartburn (heartburn that occurs two or more days a week).

Symptoms of Heartburn

The feeling of heartburn occurs when the digestive acid in your stomach backs into your esophagus, the tube that connects your throat to your stomach. 1 The most common symptoms of heartburn usually include:

  • A burning sensation in your upper abdomen that moves into your chest and throat.  
  • An uncomfortable sensation that usually occurs after eating, while bending over, or while lying down. 
  • Waking up at night with the above discomfort, especially after eating less than two hours before bed. 
  • A sour taste in your mouth, especially while lying down.
  • A small amount of stomach acid rising into the back of your throat called “regurgitation.”1

What Triggers Heartburn?

Certain foods and drinks, such as tomatoes and chocolate, have been known to trigger heartburn.

Being pregnant can also increase your risk of experiencing heartburn. 2

What Is an Antacid?

Antacids are OTC medications used to treat mild, occasional heartburn. Their active ingredients include compounds such as magnesium, calcium, and aluminum. Antacids work by neutralizing stomach acids like the digestive enzyme pepsin. 3

Pepsin is a stomach acid that helps you break down ingested food. It functions best at an acidic PH of 1.5-2. The esophageal sphincter functions like a valve that seals off the stomach to prevent acid from entering the esophagus. 4 If your esophageal sphincter is not functioning properly—or your stomach is very full—juices like pepsin can travel up into your esophagus, causing heartburn.

Antacids can neutralize some of the stomach acid that makes its way into your esophagus to provide temporary relief. 3 Antacids don’t block the production of acid and only provide heartburn relief for around one to three hours.

What Is the Active Ingredient in Nexium 24HR?

A dose of Nexium 24HR contains 20mg of an active ingredient called esomeprazole, a PPI.

While antacids neutralize the acid on contact, PPIs work by reducing the amount of stomach acid. They do this by turning off the cells in your stomach that make the acid in the first place, which reduces the amount of acid-reflux related symptoms you experience, like heartburn. PPIs get their name by inhibiting the proton pump in the walls of your stomach that “pump” out acid. 6

Nexium 24HR uses 20mg of an active ingredient called esomeprazole. Esomeprazole is a proton pump inhibitor, and OTC esomeprazole is used to treat frequent heartburn in adults (heartburn that occurs at least two or more days a week).5

How Long Does It Take Nexium 24HR to Start Working?

Since antacids neutralize acid in your stomach instead of blocking the production of acid before it starts, antacids get to work quickly but only provide relief for about one to three hours. Nexium 24HR stops the production of acid and taking just one pill a day provides you with 24 hours of protection against frequent heartburn symptoms. Nexium 24HR starts working on the first day, but it may take up to four days to reach full effect.

How About H2s? What is the Difference Between Nexium 24HR and Histamine-2 Blockers?

Histamine-2 (H2) blockers also work by blocking one of the signals that tells your body to produce acid.

They start working within one to three hours and can provide relief for up to 12 hours.

However, unlike Nexium 24HR, H2s become less effective if used to treat heartburn for more than a few days in a row.7

Use Nexium 24HR as Directed

Unless directed by your healthcare provider, you should not take Nexium 24HR for more than 14 days or more often than every four months. Please refer to package directions.

After taking a full course of Nexium 24HR, you should contact your doctor if symptoms persist or if you are experiencing diarrhea, a rash or joint pain.

To learn more about what causes heartburn and what heartburn feels like, check our other articles on the Nexium 24HR website.

  1. Heartburn or heart attack: When to worry. Mayo Clinic. Accessed on 6/21/2021. Referenced text indicated in source PDF.
  2. Heartburn - Symptoms and causes. Mayo Clinic. Accessed on 6/21/2021. Referenced text indicated in source PDF. 
  3. Antacids – StatPearls. NCBI Bookshelf. Accessed on 6/21/2021. Referenced text indicated in source PDF.
  4. Physiology, Pepsin – StatPearls. NCBI Bookshelf. Accessed on 6/21/2021. Referenced text indicated in source PDF.
  5. Esomeprazole. MedlinePlus Drug Information. Accessed on 6/21/2021. Referenced text indicated in source PDF.
  6. Proton pump inhibitors. MedlinePlus Medical Encyclopedia. Accessed on 6/21/2021. Referenced text indicated in source PDF.
  7. Over-The-Counter (OTC) Heartburn Treatment. FDA. Accessed on 6/21/2021. Referenced text indicated in source PDF.