Omeprazole
Omeprazole is used for Gastroesophageal Reflux Disease (GERD), Peptic Ulcer Disease and Erosive Esophagitis.
Pronunciation: oh-MEP-rah-zole.
Last medically reviewed: August 14, 2026, by Dr. Roshan Basnet, MBBS, MD (Internal Medicine).
- Generic name
- Omeprazole
- Brand names
- Omee, Losec, Olex, Prilosec, UlcerGard, Acimax
- Drug class
- Proton Pump Inhibitor (PPI)
Prescription And Specific Pharmacy Or Shop Products
Trade names by country: United States · United Kingdom · Canada
United Kingdom: , , · Full directory
What Omeprazole is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Omeprazole works
Omeprazole is a selective and irreversible proton pump inhibitor. It inhibits the H+/K+-ATPase enzyme system (proton pump) in the gastric parietal cells, leading to suppression of gastric acid secretion. This effect is dose-dependent and results in both basal and stimulated acid reduction. (1)
What Omeprazole is used for
Gastroesophageal Reflux Disease (GERD)
Peptic Ulcer Disease
Erosive Esophagitis
Zollinger-Ellison Syndrome
Prevention of NSAID-induced ulcers
Before taking Omeprazole
Do not take / not appropriate for
- hypersensitivity to substituted benzimidazoles or to any component of the formulation. (Contraindication) (2)
- concomitant use with rilpivirine-containing products. (Contraindication) (2)
- when used in H. pylori combination therapy, also refer to clarithromycin and amoxicillin labeling for their own contraindications. (Contraindication) (2)
Tell your clinician about
(2) (3) (4)How to take Omeprazole
- General Instructions: Take omeprazole exactly as prescribed, usually once daily before a meal. Swallow capsules or tablets whole; do not crush or chew.. Adult Dosing: Typical adult dose for GERD or ulcers: 20 mg to 40 mg once daily for 4-8 weeks. Dose may vary based on condition.. Pediatric Dosing: Dosing in children is based on weight and indication. For children over 1 year and ≥10 kg: 10 mg once daily, may increase as directed by a healthcare provider.. Administration: Take before meals, preferably in the morning. For oral suspension, mix with water as directed and take immediately.. When To Seek Review: Do not stop omeprazole suddenly without consulting your doctor, especially if used for long-term conditions. If a severe allergic reaction or serious side effect occurs, seek emergency medical attention; do not resume omeprazole without medical assessment.. Storage: Store at room temperature, away from moisture and heat. Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2) (3) (4)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, contact your prescriber or pharmacist for guidance on the missed dose. Do not take two doses at the same time.
Overdose
Symptoms of overdose may include confusion, drowsiness, blurred vision, rapid heartbeat, nausea, and vomiting. Seek emergency medical attention or contact a poison control center immediately. (2) (3) (4)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Headache (most common)
Incidence: Reported in the clinician-authored database; frequency not established
Abdominal pain, nausea, or vomiting
Incidence: Reported in the clinician-authored database; frequency not established
Diarrhea or constipation
Incidence: Reported in the clinician-authored database; frequency not established
Flatulence (gas)
Incidence: Reported in the clinician-authored database; frequency not established
Dizziness or drowsiness
Incidence: Reported in the clinician-authored database; frequency not established
Dry mouth or altered taste
Incidence: Reported in the clinician-authored database; frequency not established
Serious warnings
Long-term use may increase risk of bone fractures — serious
Symptoms: Long-term use may increase risk of bone fractures. May cause low magnesium levels with prolonged use. May mask symptoms of stomach cancer. Increased risk of Clostridioides difficile infection in hospitalized patients. Use with caution in patients with severe liver impairment.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2) (3) (4)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: Known hypersensitivity to omeprazole or other proton pump inhibitors Concurrent use with rilpivirine-containing HIV regimens
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2) (3) (4)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Omeprazole can interact with several medications, including warfarin, clopidogrel, digoxin, methotrexate, and certain antifungals (e.g., ketoconazole). It may reduce the absorption of drugs that require stomach acid for absorption. Always inform your healthcare provider of all medications and supplements you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Children
Frequency: Once daily. Weight Based: Not established for children under 1 year; for children 1 year and older, 0.7 to 1.4 mg/kg/dose once daily, not to exceed 20 mg.. Max Daily Dose: 20 mg. Max Single Dose: 20 mg. Age Restrictions: Not recommended for pediatric use in children under 1 year; safety not established in children. (2) (3) (4)
Monitoring
(2) (3) (4)Storage
Follow the exact product label and keep medicines away from children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Gastroesophageal Reflux Disease (GERD)
Dose summary: 20 mg to 40 mg orally once daily for up to 8 weeks for gastroesophageal reflux disease (GERD).
Renal context: In chronic renal impairment (creatinine clearance 10 to 62 mL/min/1.73 m2) the disposition of omeprazole was very similar to healthy subjects, with only a slight increase in bioavailability that is not clinically meaningful. No renal dose adjustment is recommended. (1)
Hepatic guidance
In hepatic impairment (Child-Pugh A, B or C) omeprazole exposure is substantially increased. Reduce to 10 mg once daily for maintenance of healing of erosive oesophagitis. The same 10 mg once-daily reduction is recommended for Asian patients for that indication.
Frequently asked questions
How long does it take for omeprazole to work?
Most people start to feel relief from symptoms within 1 to 4 days, but it may take up to 2 weeks for full effect. Continue taking as prescribed even if you feel better.
Can I take omeprazole long-term?
Long-term use should be monitored by your doctor due to risks such as bone fractures, vitamin B12 deficiency, and low magnesium. Use the lowest effective dose for the shortest duration necessary.
Is omeprazole safe during pregnancy?
Omeprazole is generally considered safe in pregnancy when clearly needed, but always consult your healthcare provider before use.
Can omeprazole be taken with food?
Omeprazole is best taken before meals, usually in the morning, for optimal absorption and effect.
What should I do if I experience severe diarrhea while taking omeprazole?
Contact your doctor immediately, as this may be a sign of a serious intestinal infection (Clostridioides difficile).
Does omeprazole interact with other medications?
Yes, omeprazole can interact with several medications, including clopidogrel, warfarin, and certain antifungals. Always inform your healthcare provider about all medicines you take.
Can children take omeprazole?
Yes, omeprazole can be prescribed for children over 1 year old for certain conditions. Dosing is based on weight and should be determined by a healthcare provider.
What happens if I take too much Omeprazole?
Taking too much Omeprazole can lead to symptoms like drowsiness, blurred vision, fast heartbeat, nausea, and vomiting. If you suspect an overdose, it is crucial to seek immediate emergency medical attention or contact a poison control center. Do not attempt to induce vomiting without professional guidance.
Can I drink alcohol while taking Omeprazole?
While there isn't a direct drug interaction between Omeprazole and alcohol, consuming alcohol can irritate the stomach lining and worsen conditions like acid reflux, which Omeprazole is prescribed to treat. It is generally advisable to limit or avoid alcohol to maximize the medication's effectiveness and prevent exacerbating your symptoms.
What is the mechanism of action of Omeprazole?
Omeprazole is a selective and irreversible proton pump inhibitor. It inhibits the H+/K+-ATPase enzyme system (proton pump) in the gastric parietal cells, leading to suppression of gastric acid secretion. This effect is dose-dependent and results in both basal and stimulated acid reduction. (1)
What is the generic name of Omeprazole?
The generic name is Omeprazole. It is sold under brand names including Omee, Losec, Olex, Prilosec, UlcerGard, Acimax.
What class of drug is Omeprazole?
Omeprazole is classed as: Proton Pump Inhibitor (PPI).
References
- OMEPRAZOLE — omeprazole capsule, delayed release — prescribing informationDailyMed, U.S. National Library of Medicine · United States · dated 2024-11-12 · accessed 2026-07-22 · source 1
- Omeprazole: MedlinePlus Drug InformationMedlinePlus, U.S. National Library of Medicine · United States · accessed 2026-07-22 · source 2
- Omeprazole: a medicine to treat heartburn and indigestionNHS · United Kingdom · dated 2025 · accessed 2026-07-22 · source 3
- Omeprazole 4 mg/ml powder for oral suspension — Patient Information Leafletelectronic Medicines Compendium (UK) · United Kingdom · dated 2026-01 · accessed 2026-07-22 · source 4
- OMEPRAZOLE 20 MG TABLET, DELAYED RELEASE [MARKSANS PHARMA LIMITED] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 5
- Esomeprazole — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 6
- omeprazole — FDA approval record (Drugs@FDA NDA022032)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 7
- Omeprazole — RxNorm normalized drug concept (RXCUI 283742)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 8
Brand names by country
Single-ingredient Omeprazole names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Prilosec OTC20.6 mg, 20 mg · the procter & gamble manufacturing company
- Prilosec10 mg, 2.5 mg · covis pharma us, inc
- DG health omperazole20 mg · dolgencorp inc
- GoodMeds 24HR Acid Reducer Omeprazole 20mg20 mg · cabinet health p.b.c.
- Omeprazole, 24/7 Life by 7-Eleven20.6 mg · lil' drug store products, inc.
- good now omeprazole20 mg · gobrands, inc
United Kingdom
Canada
- LOSEC
- OLEX
- OMEP
- PMS-OMEPRAZOLE DR
- DOM-OMEPRAZOLE DR
- RIVA-OMEPRAZOLE DR
- JAMP-OMEPRAZOLE DR
- NAT-OMEPRAZOLE DR