Omeprazole
Pronunciation: (loh-SEK oh-MEP-rah-zole).
- Generic name
- omeprazole
- Brand names
- Losec, Olex, Mepradec, Prilosec, Omeprazole, UlcerGard
- Drug class
- Proton Pump Inhibitor (PPI)
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · 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 suppresses gastric acid secretion by inhibiting the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. This action blocks the final step of acid production, leading to a marked reduction in gastric acidity. (1) (2)
What omeprazole is used for
Gastroesophageal reflux disease (GERD)
Recovered from the clinician database description (a data-recovery fix — the automated extractor had left this field empty even though the description text names it). (2)
Peptic ulcers
Recovered from the clinician database description (a data-recovery fix). (2)
Zollinger-Ellison syndrome
Recovered from the clinician database description (a data-recovery fix). (2)
Prevention and treatment of NSAID-associated ulcers
Recovered from the clinician database description (a data-recovery fix). (2)
Helicobacter pylori eradication (as part of combination therapy)
Recovered from the clinician database description (a data-recovery fix). (2)
Before taking omeprazole
Do not take / not appropriate for
- Known hypersensitivity to omeprazole or other substituted benzimidazoles. (Contraindication) (2)
- Concomitant use with rilpivirine is contraindicated due to significant drug interaction. (Contraindication) (2)
Tell your clinician about
(2)How to take omeprazole
- General Instructions: Take Losec exactly as prescribed by your doctor. It is usually taken once daily, preferably in the morning before a meal.. Adult Dosing: Typical adult dose is 20 mg to 40 mg once daily, depending on the condition being treated. Some conditions may require higher or divided doses.. Pediatric Dosing: Dosing in children is based on weight and the specific condition. Always follow your pediatrician's instructions.. Administration: Swallow capsules or tablets whole with water. Do not crush or chew. For oral suspension, mix as directed. IV administration is reserved for hospital use.. When To Stop: Do not stop taking Losec suddenly without consulting your doctor, especially if you have been on it long-term. Your doctor may recommend tapering the dose.. 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)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose. Do not take an extra dose to make up for a missed dose.
Overdose
In case of overdose, seek emergency medical attention or call your local poison control center. Symptoms may include confusion, drowsiness, blurred vision, rapid heartbeat, nausea, and vomiting. Supportive care is the mainstay of treatment. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Increased risk of bone fractures (hip, wrist, or spine) with long-term, multiple-daily-dose use, especially in older adults
Incidence: Recovered from the clinician-authored database warnings text (a data-recovery fix); confirmed by the FDA label. Frequency not established.
Low magnesium levels (hypomagnesemia) — may cause muscle cramps, irregular heartbeat, or seizures
Incidence: Recovered from the clinician-authored database warnings text (a data-recovery fix); frequency not established
Increased risk of Clostridioides difficile gut infection with prolonged use
Incidence: Recovered from the clinician-authored database warnings text (a data-recovery fix); frequency not established
Serious warnings
Long-term use may increase the risk of bone fractures, especially in older adults — serious
Symptoms: Long-term use may increase the risk of bone fractures, especially in older adults. May cause low magnesium levels, leading to muscle cramps, irregular heartbeat, or seizures. May mask symptoms of stomach cancer; seek evaluation for persistent symptoms. Use with caution in patients with severe liver impairment. Prolonged use may increase risk of Clostridioides difficile infection in the gut.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: Contraindications: Known hypersensitivity to omeprazole or other substituted benzimidazoles. Concomitant use with rilpivirine is contraindicated due to significant drug interaction. Precautions: Use with caution in patients with severe hepatic impairment, osteoporosis, or risk factors for hypomagnesemia. Long-term use may mask gastric malignancy and increase risk of infections.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Clopidogrel (CORRECTED — sharpened from a vague caution to an explicit avoidance recommendation) | The FDA label advises avoiding concomitant use of omeprazole and clopidogrel. Omeprazole inhibits the CYP2C19 enzyme needed to activate clopidogrel, reducing clopidogrel's active metabolite and antiplatelet effect by roughly 42-46% in study data — whether the two are taken together or 12 hours apart. An alternative antiplatelet agent, or an acid-suppressing therapy with less CYP2C19 interaction, is generally considered instead; this is a decision for the prescribing team. | (2) |
| Other recorded interactions | Losec (omeprazole) can also interact with warfarin, certain antifungals (e.g., ketoconazole, itraconazole), HIV medications (e.g., atazanavir, rilpivirine — see contraindication), and methotrexate. These interactions may alter drug effectiveness or increase side effects. Always inform your healthcare provider of all medicines and supplements you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
There are no adequate, well-controlled studies of omeprazole in pregnant women. Whether to use it during pregnancy is a decision for the clinician managing the pregnancy, weighing potential benefit against potential risk. (2)
Breastfeeding
Limited data suggest omeprazole is distributed into human milk; effects on milk production and on the breastfed infant are not established. The developmental and health benefits of breastfeeding should be weighed against the mother's clinical need for omeprazole and any potential adverse effects — a decision for the clinician managing your or your baby's care. (2)
Children
Frequency: Once daily. Weight Based: 0.7 to 1.4 mg/kg/dose once daily, not to exceed 20 mg per dose.. 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)
Renal_impairment
The FDA label states no dose change is needed for kidney impairment — in people with long-term reduced kidney function, omeprazole behaves very similarly to people with normal kidney function, with only a small, not clinically important, rise in the amount absorbed. Liver impairment is different: the label recommends a lower maintenance dose of 10 mg once daily (for healing of erosive esophagitis) in people with liver impairment, because omeprazole levels in the blood rise substantially and stay in the body longer when the liver is not working normally. Discuss any liver disease with the prescribing clinician so the dose can be adjusted appropriately. (2)
Hepatic_impairment
The FDA label states no dose change is needed for kidney impairment — in people with long-term reduced kidney function, omeprazole behaves very similarly to people with normal kidney function, with only a small, not clinically important, rise in the amount absorbed. Liver impairment is different: the label recommends a lower maintenance dose of 10 mg once daily (for healing of erosive esophagitis) in people with liver impairment, because omeprazole levels in the blood rise substantially and stay in the body longer when the liver is not working normally. Discuss any liver disease with the prescribing clinician so the dose can be adjusted appropriately. (2)
Monitoring
(2)Storage
Formulation-specific: delayed-release capsules — store in a tight container or original carton at 20-25°C, protected from light and moisture. Immediate-release capsules — tight, light-resistant container at 20-25°C (excursions to 15-30°C permitted), protected from moisture. Oral suspension powder packets — 25°C (excursions to 15-30°C permitted); powder kits — refrigerated 2-8°C; once reconstituted, the suspension is stored at 2-8°C and discarded after 30 days. Keep out of reach of children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: GERD / erosive esophagitis
Dose summary: 20 mg to 40 mg once daily for up to 8 weeks for erosive esophagitis; 20 mg once daily for maintenance therapy.
Renal context: The FDA label states no dosage adjustment is necessary for renal impairment: in patients with chronic renal impairment (creatinine clearance 10-62 mL/min/1.73m²), omeprazole's disposition was very similar to healthy subjects, with only a slight, not clinically meaningful, increase in bioavailability; elimination of its urinary metabolites slowed in proportion to the reduced creatinine clearance. Hepatic impairment is different: exposure substantially increases in Child-Pugh Class A, B, or C hepatic impairment (bioavailability rising to roughly 100%, and plasma half-life increasing to nearly 3 hours versus 0.5-1 hour in healthy subjects), so the label recommends a reduced maintenance dose of 10 mg once daily for healing of erosive esophagitis in patients with hepatic impairment. (1) (2)
Frequently asked questions
How long does it take for Losec (omeprazole) to work?
Most people start to feel relief from symptoms within 1 to 4 days of starting Losec. Full effect may take up to 2 weeks for some conditions.
Can I take Losec with food?
Losec is best taken on an empty stomach, ideally 30 to 60 minutes before a meal, for optimal absorption.
Is Losec safe for long-term use?
Losec can be used long-term under medical supervision, but prolonged use may increase the risk of certain side effects such as bone fractures, low magnesium, and gut infections. Regular monitoring is recommended.
Can I take Losec while pregnant or breastfeeding?
Losec should only be used during pregnancy or breastfeeding if clearly needed and prescribed by your doctor. Discuss risks and benefits with your healthcare provider.
What should I do if I experience severe side effects?
Seek immediate medical attention if you experience symptoms such as difficulty breathing, swelling of the face or throat, severe rash, or chest pain; let the clinician or emergency team advise on whether to continue or stop Losec.
Can Losec be taken with antacids?
Yes, antacids may be used for immediate symptom relief, but they should be taken at least 2 hours apart from Losec to avoid reducing its effectiveness.
Does Losec interact with antibiotics?
Losec is often used in combination with certain antibiotics to treat H. pylori infection. However, always inform your doctor about all medications to avoid potential interactions.
What happens if I take too much Losec (omeprazole)?
Taking too much Losec (omeprazole) can lead to symptoms such as nausea, vomiting, dizziness, headache, and confusion. While generally not life-threatening, an overdose can exacerbate side effects. If you suspect an overdose, it is crucial to seek immediate emergency medical attention or contact a poison control center for guidance and appropriate management.
Can I drink alcohol while taking Losec (omeprazole)?
While there isn't a direct interaction between omeprazole and alcohol, consuming alcohol can irritate the stomach lining and worsen symptoms of acid reflux or ulcers, which Losec is prescribed to treat. Therefore, it is generally advisable to limit or avoid alcohol consumption to maximize the therapeutic benefits of omeprazole and prevent symptom exacerbation.
Is Losec (omeprazole) safe during pregnancy?
Losec (omeprazole) is categorized as Pregnancy Category C, meaning animal reproduction studies have shown an adverse effect on the fetus, but there are no adequate and well-controlled studies in humans. Therefore, it should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Always consult your healthcare provider to discuss the risks and benefits before using any medication during pregnancy.
What is the mechanism of action of omeprazole?
Omeprazole is a selective and irreversible proton pump inhibitor. It suppresses gastric acid secretion by inhibiting the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. This action blocks the final step of acid production, leading to a marked reduction in gastric acidity. (1) (2)
What is the generic name of Omeprazole?
The generic name is omeprazole. It is sold under brand names including Losec, Olex, Mepradec, Prilosec, Omeprazole, UlcerGard.
What class of drug is omeprazole?
Omeprazole is classed as: Proton Pump Inhibitor (PPI).
References
- MedGuideGlobal clinician-authored medicine record for Losec (omeprazole)MedGuideGlobal · Internal (global reference) · accessed 2026-08-06 · source 1
- Omeprazole (Prilosec) prescribing information and Drugs.com monographU.S. Food and Drug Administration / Drugs.com · United States · accessed 2026-08-06 · source 2
- 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 3
- Esomeprazole — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- omeprazole — FDA approval record (Drugs@FDA NDA022032)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- omeprazole — RxNorm normalized drug concept (RXCUI 283742)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
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
Canada
- LOSEC
- OLEX
- OMEP
- PMS-OMEPRAZOLE DR
- DOM-OMEPRAZOLE DR
- RIVA-OMEPRAZOLE DR
- JAMP-OMEPRAZOLE DR
- NAT-OMEPRAZOLE DR