Omeprazole: Uses, How to Take, Side Effects & Contraindications

Updated in December 2023

Omeprazole is a medication that works by reducing acid production in the stomach. It is often prescribed for the treatment of stomach ulcers, intestinal ulcers, esophagitis from acid reflux, Zollinger-Ellison syndrome, H. pylori flare-ups and indigestion from gastric acid. It can also be prescribed to prevent tissue damage from chronic NSAID use.

This medication can be purchased at pharmacies in pill form both over-the-counter or with a prescription, 

Omeprazole should only be used as directed by a doctor, with duration doses taken in accordance with the illness being treated. 

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Common uses

Omeprazole works by reducing the production of stomach acid by inhibiting protein pumps that stimulate this process. It is indicated for the treatment of: 

  • Stomach and intestinal ulcers 
  • Esophagitis from reflux 
  • Zollinger-Ellison syndrome, which is characterized by excessive stomach acid production 
  • Maintenance of chronic esophagitis from reflux
  • Aspiration risk of stomach content during general anesthesia 
  • H. pylori bacteria that cause ulcers in the stomach
  • Stomach or duodenal erosions and ulcers, or the prevention of these from chronic NSAID use 
  • Indigestion related to gastric acid, like heartburn, nausea or stomach ache  

In addition, omeprazole can also be used to prevent flare-ups in patients with duodenal or gastric ulcers. 

How to take

Dosing for this medication depends on the problem being treated: 

1 Gastric or duodenal ulcer 

The recommended dose for gastric ulcer treatment is 20 mg, once per day. Ulcers will tend to heal in about 4 weeks in most cases, which is the recommended duration. However, the doctor may opt to prescribe omeprazole for longer. Gastric ulcers that do not respond well to this treatment can be treated with an increased dose of 40 mg per day for 8 weeks.  

The recommended dose for active duodenal ulcers is also 20 mg, once per day. Healing usually takes place within 2 weeks in most cases, however the doctor may opt to extend the duration of treatment to 4 weeks. Duodenal ulcers that do not respond well to this treatment can be treated with an increased dose of 40 mg per day for 4 weeks. 

To prevent future flare-ups of gastric ulcers that did not heal completely, the doctor may recommend a maintenance dose of 20 to 40 mg per day. For duodenol ulcers, the recommended maintenance dose is 10 mg, once per day, although the doctor can increase this to 20 to 40 mg if necessary. 

2. Reflux esophagitis

The typical dose is 20 mg taken orally once per day for 4 weeks.Some cases of reflux esophagitis may require extended treatment of an additional 4 weeks. Severe reflux esophagitis can be treated with 40 me per day for a period of 8 weeks. 

For preventative treatment of reflux esophagitis that has healed, the recommended dose 10 mg per day, which can be increased to 20 to 40 mg per day as necessary.  

3. Zollinger-Ellison syndrome 

The initial dose that is generally prescribed is 60 mg once per day. This dose can be adjusted by the doctor depending on treatment responses. Doses over 80 mg per day should be divided into at least two doses.

4. Aspiration prevention 

The typical recommended dose prescribed for people with present with an aspiration risk during general anesthesia is 40 mg the night before surgery, and another 40 mg in the morning, the day of surgery. 

5. Treatment of peptic ulcer caused by H. pylori 

The recommended dose is 20 to 40 mg, once per day, to be taken with antibiotics for the duration determined by the doctor. 

6. Ulcers and damage associated with NSAID use 

In most cases, the recommended daily dose for tissue damage from NSAID use is 20 mg, once per day for 4 weeks. If this period is not sufficient for full treatment, the doctor may prescribe an additional 4 weeks to ensure full healing. 

7. Indigestion from gastric acid 

To relieve symptoms like stomach pain and discomfort, the recommended dose is 10 to 20 mg once per day. If symptoms do not improve after 4 weeks of this treatment, the doctor may order further testing to assess the underlying cause.

8. Severe reflux esophagitis in children 

Omeprazole should only be used by children over 1. Dosing is calculated according the the child’s weight. 

Possible side effects

The most common side effects of omeprazole include headache, abdominal pain, constipation, diarrhea, gas in the stomach or intestines, nausea and vomiting. 

Contraindications for use

Omeprazole should not be used by people with severe liver problems, or who have an allergy to omeprazole or any of the components in its formula. 

It should also be avoided by pregnant or breastfeeding women, and by children under 1 year.