Is Omeprazole an Antacid? Pharmacists Answer 13 FAQs About This Common PPI

Omeprazole (Prilosec, Prilosec OTC) is a proton pump inhibitor (PPI) that treats many common digestive conditions like heartburn and gastroesophageal reflux disease (GERD). Heartburn is caused by acid reflux. Acid reflux is when stomach acid flows backwards into your esophagus (a tube that connects your mouth to your stomach). Heartburn can be mild, but if it happens often, it can be a sign of GERD, which is a more serious condition.

Omeprazole is available as a brand-name and generic medication. And it’s available over the counter (OTC) at certain doses. Other doses require a prescription. If you’re taking omeprazole, there’s a few things GoodRx pharmacists think you should know.

1. Is omeprazole an antacid?

Many people wonder if omeprazole is an antacid, and the answer is no. Antacids are common OTC medications that relieve symptoms of acid reflux, like heartburn. They work by neutralizing stomach acid. Examples of antacids include calcium carbonate (Tums) and calcium carbonate / magnesium hydroxide (Rolaids).

Like antacids, omeprazole is available OTC. But omeprazole isn’t an antacid. Omeprazole is a PPI that treats many digestive conditions that antacids can’t. For example, omeprazole treats conditions like GERD, stomach ulcers, and erosive esophagitis (inflammation of the esophagus). Antacids, on the other hand, should only be used to treat mild symptoms of acid reflux.

If you find yourself needing an OTC antacid for more than 2 weeks, talk to a healthcare professional. They might recommend stronger medication like an histamine-2 antagonist (H2 blocker) or PPI.

2. How does omeprazole work?

All PPIs work similarly to each other. They work by blocking an enzyme (protein) in the stomach known as the proton pump.

Under normal circumstances, the proton pump helps create acid in the stomach. Having some amount of acid in the stomach is a normal part of digestion, but having too much can cause acid reflux. By blocking the proton pump, PPIs limit acid production. And less acid in the stomach helps relieve symptoms of acid reflux.

PPIs are a first-choice medication for the treatment of GERD. And typically, one PPI isn’t recommended over another. So if you need a PPI, your healthcare professional can help you pick the right one for you based on your personal preferences and medical history.

3. Is generic omeprazole equally as effective as brand-name Prilosec?

Most omeprazole products are available as lower-cost generics. Though some research has questioned whether generic omeprazole is as effective as brand-name Prilosec, generic medications are considered just as effective as their brand-name counterparts.

All forms of omeprazole are delayed-release (DR) products. DR products are made so the active medication is released in the intestines (instead of the stomach). In the table below, we’ll detail all forms of omeprazole.

Brand-name Prilosec may be preferred if you have trouble swallowing. The granule packets can be mixed into water to make an oral liquid that you drink. But the generic capsules can also be opened and sprinkled onto a tablespoon of applesauce if you have trouble swallowing.

OTC products include 20 mg tablets, 20 mg capsules, and 20 mg ODTs. But if your prescriber recommends the 10 mg or 40 mg capsules, you’ll need a prescription. You’ll also need a prescription for the granule packets.

4. When is the best time to take omeprazole?

It’s typically best to take omeprazole 30 to 60 minutes before a meal. Taking it before a meal is important because food triggers your stomach to produce acid. And PPIs work best when acid is present. Taking it 30 to 60 minutes before a meal is best because it takes omeprazole this long to reach the proton pumps.

EXPERT PICKS: WHAT TO READ NEXT

• Stop the burning: Real people share what it’s like to take omeprazole for heartburn.

• Omeprazole side effects: Read what experts say about omeprazole side effects — from headaches to stomach pain — and how to manage them.

• Stopping a PPI: Want to stop omeprazole? Experts talk about the ways to do it.

If you’re only taking omeprazole once a day, it’s typically best to take your dose before breakfast. In situations where omeprazole is taken twice daily, taking it 30 to 60 minutes before breakfast and dinner is best.

Many people wonder whether taking omeprazole at night is as effective as taking it in the morning. Since there isn’t enough food in your stomach overnight to trigger acid production, taking a dose before bedtime is not as effective. If you’re having acid reflux symptoms during the night, talk to your healthcare professional. In some cases, they may recommend an H2 blocker, such as famotidine (Pepcid AC). Unlike omeprazole, H2 blockers aren’t reliant on the presence of acid to work. So you can take them without regard to meals.

5. Can you take omeprazole on an as-needed basis?

When you first start omeprazole, it’s typically best to take it daily. In many cases, the goal is to stop taking your PPI after a certain amount of time, once your symptoms resolve.

However, you may still benefit from intermittent use of a PPI, or other acid-suppressing medication, if mild symptoms pop up after you stop your PPI. In this case, PPIs, H2 blockers, or antacids may be used intermittently to help with your symptoms. Taking PPIs on an as-needed basis has been shown to be effective, and reduces your risk of long-term side effects.

But before taking PPIs as-needed, talk to your prescriber. If you’re having continued symptoms, there’s a chance you’ll need long-term acid suppression with PPIs to manage your condition. And certain conditions, such as Barrett’s esophagus, are best treated with daily PPI use long term.

6. What is the biggest side effect of omeprazole?

The most common side effect of omeprazole is a headache. In clinical trials, it happened in about 7% of people taking this medication. And the risk may be highest when you first start taking omeprazole.

Other possible side effects include stomach pain, nausea, and gas. But usually, side effects from short-term omeprazole use are mild and can be managed at home.

7. Is omeprazole safe to take long term?

Most omeprazole side effects are mild if you’re taking it short term. However, long-term use of omeprazole can cause more serious risks, although they’re rare. It may also lead to lung infections, weakened bones, and severe diarrhea. It can also increase your risk of kidney problems. However, it’s important to note that although research has associated PPIs with these risks, it’s not certain that PPIs cause them.

That said, there’s no official definition for what “long-term” PPI use is. It could be as little as 2 months. Or it could be 6 months or longer.

For most conditions (including GERD), omeprazole is taken for 1 to 2 months. But for other conditions like Barrett’s esophagus, you may need to take it for longer. If a healthcare professional suggests taking omeprazole for many months, talk to them about the risks and benefits of long-term PPI use.

Typically, OTC omeprazole should only be taken for 14 days at a time. If you need to take it longer than that to help with your symptoms, talk to your healthcare professional. You may have a more serious condition that needs to be treated.

8. Can omeprazole cause heart problems?

We’ve discussed long-term risks of omeprazole above. But whether PPI use increases the risk of heart attack is of particular interest. For example, one review of almost 3 million people with GERD found that long-term PPI use may lead to a greater risk of heart attack, whether you have existing heart problems or not. Another review of about 19,000 people with Type 2 diabetes also found that PPI use was associated with a great risk of heart attack, coronary artery disease, and heart failure. It was also associated with a higher risk of death.

But other research shows conflicting results. For example, an analysis of 10 studies didn’t find a link between PPI use and heart problems.

Even if PPIs raise the risk of heart attack, it may still be considered a rare occurrence. For example, one study found that over 4,000 people need to receive PPI treatment for one heart attack to occur. So, the benefits might outweigh the risks for many people.

If you’re concerned about the risk of heart attack with PPIs, talk to your healthcare professional. They can help you weigh the risks and benefits. They can also help make sure you take your PPI for the shortest amount of time possible. This will make it less likely to experience any negative long-term effects.

9. Does omeprazole affect your gut?

Some studies show that PPIs can affect the bacteria in your gut. In some cases, this may be harmful.

For example, some studies from the 1990s found that omeprazole treatment may change the type of bacteria in the gut and raise the amount of it. This may be harmful because bacterial overgrowth has been linked to many medical conditions, including nutritional deficiencies.

Some newer research has also found that PPIs may cause small intestinal bacterial overgrowth (SIBO) specifically. SIBO is a disruption of the normal bacteria in your small intestine specifically. It can cause many bothersome symptoms, like bloating and gas. And it can lead to nutritional deficiencies in severe cases.

Even so, experts don’t know for certain whether these changes actually cause significant health problems. And PPIs are a valuable tool for treating conditions like GERD. More research might help us better understand the risks of gut bacteria changes from omeprazole.

10. How can you stop taking omeprazole?

There are different ways to stop taking omeprazole. Some people may prefer to reduce the dose of the medication slowly (called a taper), but research shows this may not be necessary. So talk to your prescriber about whether you should taper your PPI dose or just stop it completely.

Additionally, talk to them about taking omeprazole as needed if your symptoms return. They may recommend as-needed use of a PPI or other acid-suppressing medication such as an H2 blocker or antacids, since these typically have fewer side effects than PPIs. But they aren’t as effective for conditions like GERD or esophagitis.

11. Is omeprazole safe during pregnancy?

It may be safe to take omeprazole during pregnancy. In fact, omeprazole is one of the most studied PPIs in pregnancy.

Research has shown that PPI use isn't linked to birth defects, preterm birth, or miscarriage. It may even lower the risk of preeclampsia depending on when you take it during your pregnancy.

If you’re pregnant or planning to become pregnant, talk to a healthcare professional about whether it’s safe to take omeprazole or any other PPI.

12. What should you avoid while taking omeprazole?

Omeprazole has drug interactions to be aware of. This includes potential interactions with medications such as:

• Clopidogrel (Plavix)

• Warfarin (Coumadin, Jantoven)

• Citalopram (Celexa)

• Digoxin (Lanoxin)

Besides medications, there are other things to keep in mind if you take a PPI like omeprazole. For instance, you may want to avoid, or cut back on:

• Foods that can worsen acid reflux: This is common with fried foods or fruits high in acid.

• Alcohol and caffeine: These can trigger heartburn.

• Eating too close to bedtime: Lying down can make acid move from your stomach to your esophagus and cause acid reflux symptoms.

• Tight clothing: This can put pressure on your stomach and can encourage acid to move towards your esophagus.

13. Is omeprazole the best PPI for acid reflux?

PPIs are generally considered equally effective, despite some research that shows certain PPIs, like esomeprazole (Nexium), may be more effective than omeprazole in certain situations. However, it’s not clear how much these studies translate to real-world differences between PPIs.

Additionally, PPIs have similar side effects. But omeprazole is known to have more drug interactions than other PPIs, such as pantoprazole (Protonix). So if you take several interacting medications, another PPI may be a better option.

Why trust our experts?

Written by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Our editorial standards

Meet our experts