If you have a certain kind of digestive system condition, your doctor or pharmacist may recommend taking omeprazole to reduce your stomach acid.

Omeprazole is a generic prescription medication that’s also available over the counter (OTC).

Omeprazole is used to treat the following conditions in adults:

Doctors also prescribe omeprazole for certain children with GERD or erosive esophagitis due to GERD.

OTC omeprazole is used to treat frequent heartburn (occurring 2 or more days per week) in adults.

To learn more about omeprazole’s uses, see “What is omeprazole used for?” below.

* You’ll take omeprazole with certain antibiotics for this use.

Omeprazole basics

Omeprazole belongs to a group of drugs called proton pump inhibitors (PPIs). PPIs block the production of stomach acid.

Generic omeprazole comes as a capsule and tablet that you swallow. It also comes as an orally disintegrating tablet. (This is a tablet that you put on or under your tongue to dissolve).

All three forms are delayed release. (Delayed release means the medication isn’t released as soon as it reaches your stomach.) Omeprazole comes in delayed-release forms to ensure the drug can pass through your stomach before releasing the medication into your small intestine.

All three forms of omeprazole are available OTC. In addition, the capsule is available with a prescription.

Omeprazole also comes in forms given by injection, but those are not covered in this article.

Omeprazole brand-name versions

Omeprazole is available as the brand-name prescription drug called Prilosec. But Prilosec only comes as a delayed-release suspension. Other forms of Prilosec are no longer available.

The brand-name version of OTC omeprazole oral tablet is called Prilosec OTC.

Omeprazole is a generic drug, which means it’s an exact copy of the active drug in a brand-name medication. The brand-name medication that omeprazole is based on is called Prilosec.

Generic drugs are thought to be as safe and effective as the brand-name drug they’re based on. In general, generics usually cost less than brand-name drugs do.

If you’d like to know more about using Prilosec instead of omeprazole, talk with your doctor. And explore this Healthline article to learn more about the differences between generic and brand-name drugs.

Like most drugs, omeprazole may cause mild or serious side effects. The lists below describe some of the more common side effects that omeprazole may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of omeprazole. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that omeprazole can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read the prescribing information for the omeprazole capsule, tablet, and orally disintegrating tablet.

Mild side effects of omeprazole that have been reported include:

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* To learn more about this side effect, see the “Allergic reaction” section below.

Serious side effects

Serious side effects from omeprazole can occur, but they aren’t common. If you have serious side effects from omeprazole, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of omeprazole that have been reported include:

* To learn more about this side effect, see the “Allergic reaction” section below.

Allergic reaction

Some people may have an allergic reaction to omeprazole.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, usually in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to omeprazole. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Omeprazole is used to reduce stomach acid. This can help treat various conditions related to your digestive system.

A doctor may prescribe omeprazole, but it’s also available over the counter (OTC). OTC means you can buy the medication without a doctor’s prescription.

Prescription omeprazole

Doctors prescribe omeprazole to treat the following conditions in adults:

Doctors prescribe omeprazole to treat the following conditions in children ages 2 years and older:

  • heartburn and other symptoms of GERD
  • erosive esophagitis due to GERD

Omeprazole treats all these conditions by reducing the amount of acid your stomach produces. This stops the acid from irritating the linings of your stomach, esophagus, and small intestine. If these linings have been damaged by the acid, omeprazole allows them to heal.

When used to treat H. pylori infection, omeprazole reduces stomach acid, which helps antibiotics work more effectively.

* You’ll take omeprazole with certain antibiotics for this use.

OTC omeprazole

OTC omeprazole is used to treat frequent heartburn in adults. (Heartburn is considered frequent when it occurs 2 or more days per week.) But if you’ve had heartburn for longer than 3 months, you should see your doctor before using omeprazole. This could be a sign of a more serious condition.

It’s important to note that omeprazole does not provide immediate relief from heartburn. It takes 1 to 4 days before the drug begins relieving heartburn.

Your doctor will recommend the dosage of omeprazole that’s right for you. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Forms and strengths

Omeprazole comes as a capsule and tablet that you swallow. It also comes as an orally disintegrating tablet. (This is a tablet that you put on or under your tongue to dissolve).

All three forms of omeprazole are available OTC. The capsule is also available with a prescription.

Omeprazole is available in the following strengths:

  • Capsule: 10 milligrams (mg), 20 mg, and 40 mg
  • Tablet that you swallow: 20 mg
  • Orally disintegrating tablet: 20 mg

All three forms of omeprazole are delayed release. (Delayed release means the medication isn’t released as soon as it reaches your stomach.) Omeprazole comes in delayed-release forms to ensure the drug can pass through your stomach before releasing the medication into your small intestine.

Recommended dosage

You’ll likely take omeprazole once per day.

If you take prescription omeprazole, the dosage you’ll take depends on the condition you’re using omeprazole to treat.

If you use OTC omeprazole for heartburn, you’ll take 20 mg once per day for 14 days. After this, you should wait at least 4 months before starting another round of treatment.

You should not take OTC omeprazole for more than 14 days in a row or start another round of treatment within 4 months unless your doctor recommends it.

To learn more about omeprazole’s dosage, see this article.

Questions about omeprazole’s dosage

Below are some common questions about omeprazole’s dosage.

  • What if I miss a dose of omeprazole? If you miss a dose, take the missed dose as soon as possible. But if it’s almost time for your next dose, just skip the missed dose and take your next dose at its usual time. You should not take two doses at once to make up for a missed dose. Doing so could raise your risk of side effects.
  • Will I need to use omeprazole long term? It depends. If you use OTC omeprazole, you should not take it for longer than 14 days in a row unless your doctor recommends it. If your doctor prescribes omeprazole for you, your treatment length will depend on the condition you’re taking it for. You may need to take it for a few weeks or months. For some conditions, you may need to take omeprazole long term.
  • How long does omeprazole take to work? It depends on the condition you’re taking it for. Omeprazole usually starts to relieve symptoms like heartburn after 1 to 4 days of treatment. But it may take a few weeks or months of treatment for conditions like ulcers to get better. If you take OTC omeprazole, you should see your doctor if your symptoms have not been relieved after 14 days.

Find answers to some commonly asked questions about omeprazole.

Does my risk of side effects with omeprazole depend on the dose I take (such as 20 mg or 40 mg)?

It’s possible. As with many medications, taking a higher dose of omeprazole can raise your risk of certain side effects. In particular, taking a high dose of omeprazole for a long time can raise your risk of bone fractures and vitamin B12 deficiency.

Your doctor will always prescribe the lowest dose of omeprazole that’s effective for your condition. And they’ll prescribe it for the shortest possible time.

If you have questions about your risk of side effects from omeprazole, talk with your doctor.

Is omeprazole for humans the same drug that’s used in dogs or cats?

Yes, it is. Veterinarians sometimes prescribe omeprazole to treat digestive problems, such as stomach ulcers and acid reflux, in dogs and cats. This is an off-label use of the drug. (With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for.)

You should not give omeprazole to your pet unless your veterinarian recommends it.

What should I know about alternatives to omeprazole, such as pantoprazole and famotidine?

Alternatives to omeprazole include other proton pump inhibitors (PPIs), such as pantoprazole (Protonix), and H2 receptor blockers, such as famotidine (Pepcid AC).

Drugs in both of these groups reduce stomach acid, but they work in different ways. Both groups contain drugs that are available over the counter and by prescription. But certain PPIs, such as pantoprazole, are only available with a prescription.

PPIs take longer to work than H2 receptor blockers, but their effects on stomach acid last longer. They tend to be more effective than H2 receptor blockers for treating heartburn and gastroesophageal reflux (GERD).

Your doctor or pharmacist can tell you more about alternatives to omeprazole. And they can help you determine which medication may be a good option for you.

Does omeprazole cause cancer?

No, omeprazole isn’t known to cause cancer.

Another drug used to treat heartburn and acid reflux, called ranitidine, has been linked with cancer. In 2020, some ranitidine products were found to contain unacceptable levels of a cancer-causing chemical called NMDA. As a result, the Food and Drug Administration (FDA) recommended that ranitidine products be removed from the U.S. market. But NMDA has never been found in omeprazole products.

Your doctor may check you for stomach cancer before prescribing omeprazole. But that’s because the conditions omeprazole treats can cause symptoms similar to those stomach cancer causes. This includes ongoing heartburn. Omeprazole relieves these symptoms, so it could mask undiagnosed stomach cancer.

If you’re concerned about your cancer risk, talk with your doctor.

Are anxiety or weight gain side effects of omeprazole?

It’s possible. These side effects weren’t reported in studies of omeprazole, but they’ve been reported in some people using the drug since it was approved. But it’s not clear how often this has happened or if omeprazole was the cause.

If you’re concerned about anxiety or weight gain with omeprazole, talk with your doctor.

Your doctor will explain how you should take omeprazole. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions.

Taking omeprazole

Below are instructions for taking omeprazole based on its form:

  • Capsule. Swallow the capsule whole with a glass of water. If you have trouble swallowing the capsule whole, you can open it. The capsule contains pellets with a delayed-release coating. Mix the pellets with a spoonful of cold applesauce. Swallow the mixture right away without chewing it, and then drink a glass of water to wash it down.
  • Tablet that you swallow. Swallow the tablet whole with a glass of water.
  • Orally disintegrating tablet. Place the tablet on your tongue and allow it to dissolve.Swallow the pieces without chewing them.The tablet can also be swallowed whole with a glass of water.

Accessible medication containers and labels

If it’s hard for you to read the label on your prescription, tell your doctor or pharmacist. Certain pharmacies provide medication labels that:

  • have large print
  • use braille
  • contain a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend a pharmacy that offers these options if your current pharmacy doesn’t.

Also, if you’re having trouble opening your medication bottles, let your pharmacist know. They may be able to put omeprazole in an easy-open container. Your pharmacist may also recommend tools to help make it simpler to open the drug’s container.

Questions about taking omeprazole

Below are some common questions about taking omeprazole.

  • Can omeprazole be chewed, crushed, or split? No, omeprazole should not be chewed, crushed, or split. But the capsule form can be opened and mixed with applesauce. To learn more, see “Taking omeprazole” above. You can refer to this article for tips on swallowing pills.
  • Should I take omeprazole with food? No, you should not take omeprazole with food. You should take the drug about 30 to 60 minutes before a meal. (The only exception is if you take the capsule form and mix its contents with applesauce. To learn more, see “Taking omeprazole” above.)
  • Is there a best time of day to take omeprazole? Your doctor may suggest that you take omeprazole before eating, preferably in the morning. But you and your doctor will decide the time that works best for you based on your symptoms. Taking omeprazole around the same time each day helps keep a steady level of the drug in your body. This helps omeprazole work effectively.
Questions for your doctor

You may have questions about omeprazole and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will omeprazole affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

There are several factors to consider before taking omeprazole. The medication may interact with other conditions you have, other medications you take, and certain tests you may have. Be sure to talk with your doctor about your health history and other treatments before taking omeprazole.

Some things to consider are discussed below.

Interactions

Taking a medication with certain vaccines, foods, and other things can affect how the medication works. These effects are called interactions.

Before taking omeprazole, be sure to tell your doctor about all medications you take (including prescription and over the counter types). Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with omeprazole.

For information about drug-condition interactions, see the “Warnings” section below.

Interactions with drugs or supplements

Omeprazole can interact with several types of drugs. These drugs include:

  • certain seizure drugs, such as carbamazepine (Tegretol, Carbatrol, others) and phenytoin (Dilantin, Phenytek)
  • certain antibacterial drugs, such as rifampin (Rifadin, Rimactane)
  • certain HIV drugs, such as atazanavir (Reyataz)
  • diuretic drugs (water pills), such as furosemide (Lasix)
  • the blood thinner drugs clopidogrel (Plavix), cilostazol, and warfarin (Jantoven)
  • the immunosuppressant drugs mycophenolate (Cellcept), tacrolimus (Prograf), and cyclosporine (Neoral, Sandimmune, others)
  • certain cancer drugs, such as erlotinib (Tarceva), nilotinib (Tasigna), and dasatinib (Sprycel)
  • certain antifungal drugs, such as ketoconazole and itraconazole (Sporanox)
  • the heart drug digoxin (Lanoxin)
  • methotrexate (Trexall, Otrexup, others), which is used for cancer, psoriasis, and arthritis
  • the antidepressant drug citalopram (Celexa)
  • diazepam (Valium), which treats anxiety, muscle spasms, and other conditions
  • disulfiram (Antabuse), which is used for the alcohol dependence
  • the herb St. John’s wort
  • iron supplements

This list does not contain all types of drugs that may interact with omeprazole. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of omeprazole.

Other interactions

Omeprazole can affect the results of the following laboratory tests:

  • Blood tests for serum chromogranin A (CgA). CgA levels are used to help diagnose neuroendocrine tumors. These are a type of cancer that develops in cells that release hormones.
  • Secretin stimulation test. This test is used to help diagnose problems affecting the pancreas.
  • Urine tests for tetrahydrocannabinol (THC). These tests are used to check for cannabis use.

If you have questions about having these lab tests done while taking omeprazole, talk with your doctor.

Warnings

Omeprazole can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether omeprazole is a good treatment option for you.

Talk with your doctor about your health history before you take omeprazole. Factors to consider include those described below.

Other symptoms along with heartburn. Omeprazole can be used to treat heartburn. But if you have certain other symptoms along with heartburn, they could be signs of a more serious condition. Examples of these other symptoms include:

  • trouble swallowing food or pain when swallowing food
  • vomiting blood
  • passing bloody, black, or tar-like stools
  • dizziness, feeling lightheaded, or sweating
  • chest pain or shoulder pain that spreads to your arms, neck, or shoulders
  • shortness of breath or wheezing
  • frequent chest pain
  • nausea, vomiting, or belly pain
  • unexplained weight loss

If you experience any of these symptoms, talk with your doctor before taking omeprazole. They can determine whether omeprazole is right for you.

Allergic reaction. If you’ve had an allergic reaction to omeprazole or any of its ingredients, your doctor will likely recommend that you do not take omeprazole. Ask them what other medications are better options for you.

Osteoporosis. Taking omeprazole at a high dose or for longer than 1 year can raise your risk of bone fractures. If you have osteoporosis, you may have a higher risk of this side effect. Talk with your doctor about whether omeprazole is right for you.

Liver problems. Your liver breaks down omeprazole. If you have liver problems, omeprazole may build up in your body. This can raise your risk of side effects. If you have liver problems, talk with your doctor before taking omeprazole. They may prescribe a lower dosage of omeprazole for you.

Lupus. If you have lupus, talk with your doctor before taking omeprazole. In rare cases, taking omeprazole might make your condition worse. Talk with your doctor about whether omeprazole is right for you.

Asian heritage. If you’re of Asian descent, your body might not break down omeprazole as well. This could make the drug build up in your body, which could raise your risk of side effects. If you need to take omeprazole long term, your doctor may prescribe a lower dosage for you.

Omeprazole and alcohol

Omeprazole isn’t known to interact with alcohol. But drinking alcohol while you’re taking omeprazole could raise your risk of certain side effects. These include nausea, headache, and diarrhea. Drinking alcohol may also worsen the symptoms of the condition you’re taking omeprazole to treat.

If you drink alcohol, talk with your doctor about how much may be safe to consume while you’re taking omeprazole.

Pregnancy and breastfeeding

Research hasn’t found any increased risk of harmful effects when omeprazole is used during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor about the possible risks and benefits of taking omeprazole.

Limited research suggests that omeprazole may pass into breast milk in small amounts. But it’s not known whether this has harmful effects in a breastfed child.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before taking omeprazole.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

Financial assistance to help you pay for omeprazole may be available. Medicine Assistance Tool and NeedyMeds are two websites that provide resources to help reduce the cost of omeprazole.

These websites also offer tools to help you find low cost healthcare and certain educational resources. To learn more, visit their websites.

Do not take more omeprazole than your doctor prescribes. Using more than this can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

What to do in case you take too much omeprazole

Call your doctor if you think you’ve taken too much omeprazole. You can also call 800-222-1222 to reach the American Association of Poison Control Centers or use its online resource. But if you have severe symptoms, immediately call 911 or your local emergency number. Or go to the nearest emergency room.

If you have questions about taking omeprazole, talk with your doctor or pharmacist. Examples of questions you may want to ask include:

  • What’s the maximum dose of omeprazole I could be prescribed?
  • Can I take omeprazole with other drugs used for heartburn?
  • Can I take omeprazole to prevent heartburn?
  • How can I safely stop taking omeprazole?

To learn more about omeprazole, see this article:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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