Highlights for omeprazole

  1. Omeprazole oral capsule is available as a generic drug. It doesn’t have a brand-name version.
  2. Omeprazole also comes as a liquid suspension you take by mouth.
  3. Omeprazole oral capsule is used to reduce the amount of acid in your stomach. It’s used to treat gastric or duodenal ulcers, gastroesophageal reflux disease (GERD), erosive esophagitis, and hypersecretory conditions. This drug is also used to treat stomach infections caused by Helicobacter pylori bacteria.

Important warnings

  • Severe diarrhea warning: This drug may increase your risk of severe diarrhea. This may be caused by an infection in your intestine caused by the bacteria Clostridium difficile. Call your doctor right away if you have watery diarrhea, stomach pain, and a fever that won’t go away.
  • Bone fractures warning: People who take several doses of a proton pump inhibitor drug, such as omeprazole, every day for a year or longer may have an increased risk of bone fractures. These bone breaks may be more likely to happen in your hip, wrist, or spine. Talk to your doctor about your risk of bone fractures. You should take this drug exactly as prescribed by your doctor. They should prescribe the lowest dose possible for the shortest amount of time needed for your treatment.
  • Low magnesium levels warning: Taking this drug for 3 months or longer can cause low magnesium levels in your body. Your risk is higher if you take omeprazole for a year or longer. Call your doctor right away if you have symptoms of low magnesium. These can include seizures, abnormal or fast heart rate, jitteriness, jerking movements or shaking, and muscle weakness. They can also include cramps or muscle aches and spasms of your hands, feet, and voice box. Your doctor may check your magnesium levels before and during your treatment with this drug.
  • Cutaneous lupus erythematosus and systemic lupus erythematosus warning: Omeprazole can cause cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE). CLE and SLE are autoimmune diseases. Symptoms of CLE can range from a rash on the skin and nose, to a raised, scaly, red or purple rash on certain parts of the body. Symptoms of SLE can include fever, tiredness, weight loss, blood clots, heartburn, and stomach pain. If you have any of these symptoms, call your doctor.

What is omeprazole?

Omeprazole oral capsule is a prescription drug that’s only available in a generic form. It doesn’t have a brand-name version. Omeprazole is also available as an oral suspension and comes as an over-the-counter medication.

Prescription omeprazole oral capsule is a delayed-release drug. A delayed-release drug slows the release of the medication until it passes through your stomach. This delay keeps the drug from being inactivated by your stomach.

Why it's used

Omeprazole is used to treat conditions caused by too much acid production in the stomach, such as:

This drug may be used as part of a combination therapy. This means you may need to take it with other medications.

How it works

Omeprazole belongs to a class of drugs called proton pump inhibitors (PPIs). A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Omeprazole works by decreasing the amount of acid your stomach produces. It does this by blocking the proton pump in the cells of your stomach. The proton pump works in the final step of acid production. When the proton pump is blocked, your stomach makes less acid. This should decrease your symptoms.

Omeprazole side effects

Omeprazole oral capsule doesn’t cause drowsiness. However, it can cause other side effects.

More common side effects

The side effects from this drug are slightly different for children and adults.

  • Adult side effects can include:
    • headache
    • stomach pain
    • nausea
    • diarrhea
    • vomiting
    • gas
  • Children’s side effects can include the above, plus the following:
    • fever

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Low magnesium levels. Using this drug for 3 months or longer can cause low magnesium levels. Symptoms can include:
    • seizures
    • abnormal or fast heart rate
    • tremors
    • jitteriness
    • muscle weakness
    • dizziness
    • spasms of your hands and feet
    • cramps or muscle aches
    • spasm of your voice box
  • Vitamin B-12 deficiency. Using this drug for longer than 3 years can make it harder for your body to absorb vitamin B-12. Symptoms can include:
    • nervousness
    • neuritis (inflammation of a nerve)
    • numbness or tingling in your hands and feet
    • poor muscular coordination
    • changes in menstruation
  • Severe diarrhea. This may be caused by a Clostridium difficile infection in your intestines. Symptoms can include:
    • watery stool
    • stomach pain
    • fever that doesn’t go away
  • Inflammation of your stomach lining. Symptoms can include:
    • stomach pain
    • nausea
    • vomiting
    • weight loss
  • Bone fractures
  • Kidney damage. Symptoms can include:
    • flank pain (pain in your side and back)
    • changes in urination
  • Cutaneous lupus erythematosus (CLE). Symptoms can include:
    • rash on the skin and nose
    • raised, red, scaly, red or purple rash on your body
  • Systemic lupus erythematosus (SLE). Symptoms can include:
    • fever
    • tiredness
    • weight loss
    • blood clots
    • heartburn

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.

Omeprazole may interact with other medications

Omeprazole oral capsule can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Examples of drugs that can cause interactions with omeprazole are listed below.

Drugs you should not use with omeprazole

Do not take these drugs with omeprazole. Doing so can cause dangerous effects in the body. Examples of these drugs include:

  • Atazanavir, rilpivirine, and nelfinavir. Omeprazole may greatly decrease the effects of these drugs and could make them less effective over time. You shouldn’t take these drugs with omeprazole.
  • Clopidogrel. Omeprazole may reduce the effects of clopidogrel, causing your blood to clot. You shouldn’t take this drug with omeprazole.

Interactions that increase the risk of side effects

  • Side effects from omeprazole: Taking omeprazole with certain medications raises your risk of side effects from omeprazole. This is because the amount of omeprazole in your body is increased. Examples of these drugs include:
    • Voriconazole. This drug may increase the levels of omeprazole in your body. If you’re taking high doses of omeprazole, your doctor may adjust your omeprazole dose.
  • Side effects from other drugs: Taking omeprazole with certain medications raises your risk of side effects from these drugs. Examples of these drugs include:
    • Saquinavir. Omeprazole may greatly increase the levels of saquinavir in your body. Your doctor may lower your dose of saquinavir.
    • Digoxin. Omeprazole may increase the levels of digoxin in your body. Your doctor may monitor the levels of digoxin in your blood.
    • Warfarin. Omeprazole may increase the levels of warfarin in your body. Your doctor may monitor you for symptoms of bleeding.
    • Phenytoin. Omeprazole may increase the levels of phenytoin in your body. Your doctor may watch you for high levels of phenytoin.
    • Cilostazol. Omeprazole may increase the levels of cilostazol in your body. Your doctor may lower your dose of cilostazol.
    • Tacrolimus. Omeprazole may increase the levels of tacrolimus in your body. Your doctor may monitor the level of tacrolimus in your body.
    • Methotrexate. Omeprazole may increase the effects of methotrexate. Your doctor may adjust your dose depending on the levels of methotrexate in your body.
    • Diazepam. Omeprazole may increase the levels of diazepam in your body. Your doctor may watch you for more side effects from diazepam.
    • Citalopram. Omeprazole may increase the amount of citalopram in your body, leading to an increased risk of heart rhythm problems. Your doctor may limit your dosage of citalopram.

Interactions that can make your drugs less effective

  • When other drugs are less effective: When certain drugs are used with omeprazole, they may not work as well. This is because the amount of these drugs in your body may be decreased. Examples of these drugs include:
    • Ampicillin esters. Omeprazole can keep your body from absorbing antibiotics like ampicillin well. Ampicillin may not work as well to treat your infection.
    • Ketoconazole. Omeprazole can keep your body from absorbing ketoconazole well. Ketoconazole may not work as well to treat your infection.
    • Mycophenolate mofetil (MMF). Omeprazole can keep your body from absorbing MMF well. MMF may not work as well. It isn’t known how this may affect your risk of organ rejection.
    • Iron salts. Omeprazole can keep your body from fully absorbing drugs that contain iron.
    • Erlotinib. Omeprazole can keep your body from absorbing erlotinib well. Erlotinib may not work as well to treat your cancer.
  • When omeprazole is less effective: When omeprazole is used with certain drugs, it may not work as well to treat your condition. This is because the amount of omeprazole in your body may be decreased. Examples of these drugs include:
    • St. John’s wort
    • Rifampin

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

Omeprazole warnings

Allergy warning

Omeprazole can cause a severe allergic reaction. Symptoms can include:

  • rash
  • face swelling
  • throat tightness
  • trouble breathing

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 911 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it or other proton pump inhibitors. Taking it again could be fatal (cause death).

Warnings for people with certain health conditions

For people with liver problems: This drug may change the way your liver works. If you have severe liver problems, your doctor may decrease your dose.

For people with a vitamin B-12 deficiency: This drug reduces the amount of acid in your stomach. You need stomach acid to absorb vitamin B-12. If you’ve been taking this drug for more than 3 years, talk to your doctor. Your doctor may monitor your vitamin B-12 levels and give you vitamin B-12 injections if needed.

For people with osteoporosis: People who take multiple doses of this drug every day for a year or longer may have an increased risk of fractures. These fractures may be more likely to happen in your hip, wrist, or spine. If you already have osteoporosis, you already have an increased risk of bone fractures.

For people with low magnesium levels in the blood: This drug can cause low magnesium levels if you’ve been taking it for 3 months or longer. Having low magnesium levels can be serious. Your doctor will monitor your magnesium levels during your treatment with this drug and give you supplements if needed.

Warnings for other groups

For pregnant women: There isn’t enough good information on the use of omeprazole in pregnant women to determine the risk to a pregnancy.

Talk to your doctor if you’re pregnant or planning to become pregnant. This drug should only be used if the potential benefit justifies the potential risk to the fetus.

For women who are breastfeeding: Omeprazole passes into breast milk and may cause side effects in a child who is breastfed. Talk to your doctor if you breastfeed your child. You may need to decide whether to stop breastfeeding or stop taking this medication. Call your doctor right away if you become pregnant while taking this drug.

For seniors: The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

For children: This drug hasn’t been studied in children with duodenal ulcers, gastric ulcers, or hypersecretory conditions. It shouldn’t be used in people younger than 16 years for these conditions.

This drug hasn’t been shown to be safe or effective in children younger than 1 year of age with gastroesophageal reflux disease (GERD).

How to take omeprazole

This dosage information is for omeprazole oral capsule. All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

Forms and strengths

Generic: Omeprazole

  • Form: delayed-release oral capsule
  • Strengths: 10 mg, 20 mg, 40 mg

Dosage for duodenal ulcer or stomach infection

Adult dosage (ages 18 years and older)

  • Active duodenal ulcer: 20 mg taken once per day for up to 4 weeks. Some people may need more than 4 weeks of treatment.
  • Duodenal ulcer caused by Helicobacter pylori infection:
    • 20 mg taken twice per day for 10 days with amoxicillin and clarithromycin.
      • If you had an ulcer when you started medication, you may also need 20 mg once daily for an additional 18 days.
    • 40 mg taken once per day for 14 days with clarithromycin.
      • If you had an ulcer when you started medication, you may also need 20 mg once daily for an additional 14 days.

    Child dosage (ages 16–17 years)

    • Active duodenal ulcer: 20 mg taken once per day for up to 4 weeks. Some people may need more than 4 weeks of treatment.
    • Duodenal ulcer caused by Helicobacter pylori infection:
      • 20 mg taken twice per day for 10 days with amoxicillin and clarithromycin.
        • If you had an ulcer when you started medication, you may also need 20 mg once daily for an additional 18 days.
      • 40 mg taken once per day for 14 days with clarithromycin.
        • If you had an ulcer when you started medication, you may also need 20 mg once daily for an additional 14 days.

      Child dosage (ages 0–15 years)

      This drug hasn’t been studied in children. It shouldn’t be used in people younger than 16 years.

      Dosage for gastric (stomach) ulcer

      Adult dosage (ages 18 years and older)

      40 mg taken once per day for 4–8 weeks.

      Child dosage (ages 16–17 years)

      40 mg taken once per day for 4–8 weeks.

      Child dosage (ages 0–16 years)

      This drug hasn’t been studied in children younger than 16 years. It shouldn’t be used in people younger than 16 years.

      Dosage for gastroesophageal reflux disease (GERD)

      Adult dosage (ages 18 years and older)

      • Gastroesophageal reflux disease (GERD): 20 mg taken once per day for up to 4 weeks.
      • Esophagitis with GERD symptoms: 20 mg taken once per day for 4–8 weeks.

      Child dosage (ages 17 years)

      • Gastroesophageal reflux disease (GERD): 20 mg taken once per day for up to 4 weeks.
      • Esophagitis with GERD symptoms: 20 mg taken once per day for 4–8 weeks.

      Child dosage (ages 1–16 years)

      Your child’s dosage will be based on their weight:

      • 10 kg to less than 20 kg (22 lb to less than 44 lb): 10 mg taken once per day.
      • 20 kg (44 lb) or more: 20 mg taken once per day

      Child dosage (ages 0–1 year)

      This drug hasn’t been studied in children younger than 2 years. It shouldn’t be used in people younger than 2 years.

      Dosage for erosive esophagitis

      Adult dosage (ages 18 years and older)

      • Maintenance: 20 mg once daily.

      Child dosage (age 17 years)

      • Maintenance: 20 mg once daily.

      Child dosage (ages 2–16 years)

      Your child’s dosage will be based on their weight:

      • 10 kg to less than 20 kg (22 lb to less than 44 lb): 10 mg taken once per day.
      • 20 kg (44 lb) or more: 20 mg taken once per day.

      Child dosage (ages 0–1 year)

      This drug hasn’t been studied in children younger than 2 years. It shouldn’t be used in people younger than 2 years.

      Special dosage considerations

      People of Asian descent: Your doctor may give you a lower dosage of this medication, especially if you’re taking it for erosive esophagitis.

      Dosage for pathological hypersecretory conditions

      Adult dosage (ages 18 and older)

      • Typical starting dose: 60 mg taken once per day.
      • Dose increases: Your doctor will increase your dose as needed.
      • Maximum dose: 360 mg per day. If you need to take more than 80 mg per day, your doctor will have you take it in divided doses.

      Child dosage (ages 16–17 years)

      • Typical starting dose: 60 mg taken once per day.
      • Dose increases: Your doctor will increase your dose as needed.
      • Maximum dose: 360 mg per day. If you need to take more than 80 mg per day, your doctor will have you take it in divided doses.

      Child dosage (ages 0–15 years)

      This drug hasn’t been studied in children younger than 16 years. It shouldn’t be used in people younger than 16 years.

      Special considerations

      People of Asian descent. Your doctor may give you a lower dose of this medication, especially if you’re taking it for erosive esophagitis.

      Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.

Take as directed

Omeprazole oral capsule is used for short-term treatment of duodenal and gastric ulcers and gastroesophageal reflux disease (GERD). It’s used for long-term treatment of erosive esophagitis and pathological hypersecretory conditions. It comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug suddenly or don’t take it at all: Your acid reflux, heartburn, or ulcer symptoms may not improve. They may even get worse.

If you miss doses or don’t take the drug on schedule: Your medication may not work as well or may stop working completely.

If you take too much: You could have dangerous levels of the drug in your body. Symptoms can include:

  • confusion
  • drowsiness
  • blurred vision
  • fast heart rate
  • nausea
  • vomiting
  • sweating
  • flushing
  • headache
  • dry mouth

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 911 or go to the nearest emergency room right away.

What to do if you miss a dose: Take your dose as soon as you remember. If you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working: You should have decreased pain and acid reflux symptoms.