OMEZ is a prescription medicine that reduces the amount of acid made in your stomach. It contains omeprazole, a proton pump inhibitor (PPI). Lowering stomach acid helps ulcers to heal, eases heartburn caused by gastro-oesophageal reflux disease (GORD), and treats conditions where the stomach produces too much acid.
What it is and what it is used for
What it is
- OMEZ (omeprazole) is a proton pump inhibitor. PPIs switch off the acid “pumps” in the stomach lining to reduce acid production.
What it is used for (adults)
- Duodenal ulcer: treatment and prevention of relapse.
- Gastric ulcer and reflux oesophagitis (inflammation of the food pipe from acid).
- Long-term management of reflux oesophagitis.
- Zollinger-Ellison Syndrome (a condition causing very high acid output).
- Symptomatic relief of heartburn in patients with GORD and short-term relief of functional dyspepsia.
- Helicobacter pylori-positive duodenal ulcers as part of an eradication programme with appropriate antibiotics.
- NSAID-associated gastric and/or duodenal ulcer/erosions: treatment.
- Prevention of NSAID-associated gastric/duodenal ulcer/erosions and reduction of relapse risk in patients on NSAIDs.
What it is used for (children)
- Short-term (up to 3 months) treatment of severe ulcerative reflux oesophagitis in children from 1 year of age, when resistant to previous medical treatment.
How it works
Your stomach has microscopic acid pumps (called the H⁺/K⁺-ATPase). OMEZ blocks these pumps, so less acid is released into the stomach. With less acid, ulcers can heal and reflux symptoms (like burning behind the breastbone) ease. OMEZ blocks both day-to-day (basal) acid production and stimulated acid secretion (for example, after a meal). It does not block the receptors for acetylcholine, histamine, or gastrin; it acts after these signals by turning off the final step of acid production.
Who should NOT use this medicine
Do not use OMEZ if:
- You are allergic to omeprazole or any of the capsule ingredients.
- You are pregnant or breastfeeding. Safety in pregnancy and lactation has not been established.
- You take nelfinavir (an antiretroviral medicine).
- You are taking atazanavir – co-administration is not recommended.
Speak to your doctor urgently before starting if you have any “alarm” symptoms:
- Unintentional weight loss.
- Recurrent vomiting.
- Difficulty swallowing (dysphagia).
- Vomiting blood (haematemesis) or black stools (melaena).
These may indicate a more serious condition; treatment with OMEZ could mask symptoms and delay diagnosis, so cancer must be excluded in these cases.
Warnings and precautions (Read before use)
- Liver or kidney issues:
- Hepatic impairment can increase omeprazole levels; a lower daily dose (10–20 mg) is generally sufficient.
- The long-term safety of OMEZ in renal and/or hepatic impairment has not been established.
- Children: Experience is limited. Some children with chronic conditions may need long-term therapy, but this is not recommended.
- Antiretrovirals: Do not use with nelfinavir. Atazanavir with PPIs is not recommended; if unavoidable, close monitoring is required and omeprazole 20 mg should not be exceeded.
- Vitamin B12: Long-term acid reduction can reduce vitamin B12 absorption (due to low stomach acid). Consider this in patients at risk of deficiency.
- Clopidogrel: OMEZ inhibits CYP2C19 and can reduce the activation of clopidogrel. Concomitant use should be discouraged.
- Bone fractures: High doses and long-term use (>1 year) may slightly increase hip, wrist, and spine fracture risk (10–40% increase seen in observational studies), especially in elderly people or those with other risks. Ensure adequate calcium and vitamin D as per clinical guidance.
- Low magnesium (hypomagnesaemia): After ≥3 months (often a year) of PPI use, severe low magnesium can occur (fatigue, muscle cramps/tetany, confusion, seizures, dizziness, abnormal heart rhythms). This usually improves after stopping OMEZ and replacing magnesium. If long-term therapy is expected, or if taken with digoxin or diuretics, your healthcare provider may check magnesium levels before and during treatment.
- Subacute cutaneous lupus erythematosus (SCLE): Very rare. If you develop ring-shaped or scaly skin lesions on sun-exposed areas, with or without joint pain, seek medical help and your doctor may stop OMEZ.
- Lab test interference: OMEZ can increase Chromogranin A (CgA), which may interfere with tests for neuroendocrine tumours. Stop OMEZ for at least 5 days before CgA testing. If results are still high, repeat 14 days after stopping.
- Infections and gut changes: Long-term acid suppression may increase the number of normal stomach bacteria and is associated with a higher risk of gastrointestinal infections (e.g., Salmonella, Campylobacter, Clostridium difficile).
- Clostridium difficile-associated diarrhoea (CDAD): PPIs may increase risk, especially in hospitalised patients. Consider this diagnosis if diarrhoea persists.
- Kidney inflammation (Acute tubulointerstitial nephritis): Can occur at any time during therapy and may lead to acute kidney injury. Symptoms range from allergic-type reactions to non-specific signs of reduced kidney function (malaise, nausea, poor appetite). Stop OMEZ and seek medical evaluation if suspected.
- Use the lowest effective dose for the shortest time needed for your condition.
- Contains mannitol: Rarely causes hypersensitivity and may have a laxative effect.
- Driving and machinery: OMEZ may cause drowsiness or reduced concentration, which can be worsened by alcohol or other sedatives. Especially when starting therapy, avoid driving or operating machinery if affected.
Pregnancy, planning pregnancy, and breastfeeding
Safety in pregnancy and lactation has not been established.Speak to your doctor or pharmacist before use.
Interactions
Important: Always tell your doctor and pharmacist about all medicines you take.
- Clopidogrel: OMEZ reduces clopidogrel’s activation via CYP2C19. Concomitant use should be discouraged.
- CYP-metabolised medicines: OMEZ is metabolised by the liver (CYP system) and can affect other medicines processed by these enzymes.
- Diazepam, warfarin, phenytoin: Elimination may be prolonged. INR (for warfarin) and phenytoin levels should be monitored; dose adjustments may be needed.
- Digoxin: OMEZ 20 mg daily can increase digoxin bioavailability by ~10%. Toxicity is rare but use caution, especially at high OMEZ doses in elderly patients; consider therapeutic drug monitoring.
- Antiretrovirals:
- Nelfinavir: Contraindicated with OMEZ (significant reduction in nelfinavir and its active metabolite).
- Atazanavir: Not recommended with OMEZ (markedly reduced exposure). Increasing atazanavir dose may not overcome the effect; avoid the combination.
- Tacrolimus: Serum levels may increase. Monitor tacrolimus concentrations and renal function; adjust dose if required.
- Methotrexate: Levels can increase when given with OMEZ. With high-dose methotrexate, consider temporarily stopping OMEZ.
- Antifungals/other medicines affected by gastric pH:
- Posaconazole and erlotinib: Absorption significantly reduced; avoid concomitant use.
- Ketoconazole and itraconazole: Absorption reduced; efficacy may be impaired.
- Vitamin B12: Long-term acid suppression can reduce cyanocobalamin absorption.
- Laboratory tests: OMEZ can raise CgA, potentially confusing tests for certain tumours; follow the 5-day stop guidance above.
How to take (Step-by-step)
General guidance
- Timing: Take OMEZ in the morning.
- How to swallow: Swallow the capsule whole with half a glass of liquid. Do not crush or chew the capsule or pellets.
- With food: Food does not affect omeprazole’s bioavailability (no specific instruction to take with or without food is required in the source).
- Do not change your dose without medical advice, especially in long-term treatment.
Adult dosing (follow your doctor’s instructions):
- Duodenal ulcer: 20 mg once daily for 2–4 weeks. Some patients who did not respond to other treatments may need 40 mg once daily.
- Prevention of duodenal ulcer relapse: 10 mg once daily. If needed, increase to 20–40 mg once daily.
- H. pylori-positive duodenal ulcer: As above plus appropriate antibiotics as part of an eradication programme.
- Gastric ulcer and reflux oesophagitis: 20 mg once daily for 4–8 weeks. If refractory to other regimens, 40 mg once daily may be effective.
- Long-term management of reflux oesophagitis: 20 mg once daily; if necessary, up to 40 mg once daily. In severe or symptomatic recurrent oesophagitis, continue 20 mg once daily.
- NSAID-associated gastric/duodenal lesions (with or without ongoing NSAIDs): 20 mg once daily. Most heal within 4 weeks; if not fully healed, continue for another 4 weeks.
- Prevention of NSAID-associated lesions and dyspeptic symptoms: 20 mg once daily.
- Symptomatic GORD: 20 mg once daily. Some patients may respond to 10 mg daily; tailor the dose individually. If symptoms are not controlled after 2 weeks at 20 mg daily, further investigation is recommended.
- Zollinger-Ellison Syndrome: 60 mg once daily, then adjust individually as needed. For >80 mg/day, split into two doses (morning and evening).
Paediatric dosing (children ≥1 year) — severe ulcerative reflux oesophagitis resistant to prior treatment (short-term up to 3 months):
- 10–20 kg: 10 mg once daily; if needed, increase to 20 mg once daily.
- >20 kg: 20 mg once daily; if needed, increase to 40 mg once daily.
Special populations
- Elderly: No routine dose reduction required.
- Renal impairment: No dose reduction required.
- Hepatic impairment: Bioavailability and half-life are increased; in general, 10–20 mg daily is sufficient.
Missed dose and overdose
- Missed dose: Not specified in the source. Speak to your pharmacist or doctor for personalised advice.
- Overdose: Reported symptoms include blurred vision, confusion, sweating, flushing, headache, malaise, nausea, tachycardia. There is no specific antidote; treatment is supportive. Omeprazole is not readily dialysable. If overdose is suspected, seek medical attention.
Dosing table
Adults (follow medical advice; doses are once daily unless stated)
| Indication | Usual dose | Duration | Notes |
|---|---|---|---|
| Duodenal ulcer | 20 mg | 2–4 weeks | Refractory to other regimens: 40 mg |
| Prevention of duodenal ulcer relapse | 10 mg | Ongoing | May increase to 20–40 mg if needed |
| H. pylori-positive duodenal ulcer | As above | Per regimen | Use with appropriate antibiotics as eradication therapy |
| Gastric ulcer | 20 mg | 4–8 weeks | Refractory: 40 mg |
| Reflux oesophagitis (acute) | 20 mg | 4–8 weeks | Refractory: 40 mg |
| Reflux oesophagitis (long-term management) | 20 mg | Ongoing | If necessary, increase up to 40 mg |
| Severe/recurrent symptomatic reflux oesophagitis | 20 mg | Ongoing | Continue at 20 mg once daily |
| NSAID-associated gastric/duodenal lesions (treatment) | 20 mg | Usually 4 weeks | If not healed, an additional 4 weeks |
| Prevention of NSAID-associated lesions/dyspeptic symptoms | 20 mg | Ongoing | While on NSAIDs |
| Symptomatic GORD | 20 mg | Review after 2 weeks | Some respond to 10 mg; investigate if no control after 2 weeks at 20 mg |
| Zollinger-Ellison Syndrome | 60 mg (initial) | Individualised | If >80 mg/day, divide into two daily doses |
Children (≥1 year) — severe ulcerative reflux oesophagitis resistant to prior treatment
| Weight | Starting dose | If needed |
|---|---|---|
| 10–20 kg | 10 mg once daily | Increase to 20 mg once daily |
| >20 kg | 20 mg once daily | Increase to 40 mg once daily |
Note: Paediatric use is short-term (up to 3 months).
Possible side effects
Below is a consolidated list based on the package insert. If any side effect worries you, speak to your doctor or pharmacist. Seek urgent help for serious reactions (see the final subsection).
Common (reported as “Frequent”)
- Headache (in some cases severe enough to stop treatment).
- Diarrhoea (occasionally severe enough to stop treatment).
- Constipation.
- Abdominal pain/colic.
- Nausea or vomiting.
- Flatulence.
- Gastric glandular cysts and fundic gland polyps (benign).
Less common (reported as “Less frequent”)
- Blood/lymph: Low white cells (leucopenia), low platelets (thrombocytopenia), agranulocytosis, pancytopenia.
- Endocrine: Gynaecomastia.
- Metabolism: Hyponatraemia, hypomagnesaemia.
- Psychiatric: Reversible confusion, agitation, aggression, depression, hallucinations (mostly in severely ill patients).
- Nervous system: Dizziness, drowsiness (somnolence), insomnia, paraesthesias.
- Eyes: Blurred vision.
- Vascular: Peripheral oedema.
- Respiratory: Bronchospasm.
- Gastrointestinal: Dry mouth, stomatitis, oesophageal candidiasis, taste disturbances.
- Liver: Raised liver enzymes, hepatitis (with or without jaundice), hepatic encephalopathy.
- Skin: Rash, urticaria, itching (pruritus), photosensitivity, bullous eruptions, toxic epidermal necrolysis, Stevens-Johnson syndrome, alopecia, erythema multiforme.
- Musculoskeletal: Weakness (asthenia), joint pain (arthralgia), muscle pain (myalgia), bone fractures.
- Renal/urinary: Interstitial nephritis.
- Immune: Hypersensitivity reactions (fever, angioedema, bronchospasm, interstitial nephritis).
- General: Malaise.
Frequency not known (listed in the insert without a set frequency)
- Clostridium difficile-associated diarrhoea (CDAD).
- Microscopic colitis.
Serious—seek urgent help
Stop OMEZ and get medical attention immediately if you notice:
- Allergic reactions such as face, tongue, or throat swelling (angioedema), wheezing/shortness of breath (bronchospasm), widespread rash or blistering (Stevens-Johnson syndrome, toxic epidermal necrolysis), fever.
- Severe persistent diarrhoea, especially if watery or with blood (possible C. difficile infection).
- Yellowing of the skin or eyes, very dark urine, or confusion (possible liver problems, including hepatic encephalopathy).
- Unexplained bruising/bleeding, recurrent infections, or extreme tiredness (possible blood cell disorders).
- Sudden reduction in urine, swelling in legs, or flank pain (possible kidney inflammation).
- Severe low magnesium symptoms: muscle cramps/twitches, seizures, confusion, or heart rhythm changes.
- Ring-shaped or scaly skin lesions, particularly on sun-exposed skin, with joint pain (possible SCLE).
What to do: Stop the medicine and contact your doctor or the nearest emergency unit.
Storage and disposal
- Store at or below 25 °C.
- Protect from light and moisture.
- Keep blisters in the outer carton until use.
- Keep containers tightly closed.
- Shelf life: 3 years.
- Keep out of the sight and reach of children.
- Disposal: Any unused product or waste should be discarded according to local requirements (ask your pharmacist).
What the medicine contains
- Active ingredient: Omeprazole 10 mg, 20 mg, or 40 mg per capsule.
- Excipients include: crospovidone, hydroxypropyl methyl cellulose, magnesium stearate, mannitol (sugar; may have a laxative effect and rarely cause hypersensitivity), meglumine, methacrylic acid copolymer (Type C), poloxamer, povidone, triethyl citrate.
- Capsule shell components: gelatin, titanium dioxide, and permitted colourants (including D&C red #28, FD&C blue #1, FD&C red #40, FD&C yellow #6; yellow iron oxide in 10 mg and 40 mg; black iron oxide in 20 mg).
- Printing ink: mixture of iron oxides and approved lakes with pharmaceutical glaze and propylene glycol.
If you have known allergies to colourants or excipients, review this list with your pharmacist.
Pack information and appearance
- Pharmaceutical form: Capsule containing off-white to pale yellow enteric-coated pellets.
- OMEZ 10 mg: Capsule with opaque lavender cap and opaque yellow body; imprinted “Omeprazole 10 mg” on cap and “R157” on body (black ink).
- OMEZ 20 mg: Capsule with opaque lavender cap and opaque iron grey body; imprinted “Omeprazole 20 mg” on cap and “R158” on body.
- OMEZ 40 mg: Capsule with opaque yellow cap and opaque purple body; imprinted “Omeprazole 40 mg” on cap and “R159” on body.
Pack sizes
- OMEZ 10 mg: Blisters 30 or 100; white HDPE bottles 30 or 100.
- OMEZ 20 mg: Blisters 14, 30 or 100; white HDPE bottles 14, 30, 100 or 1000.
- OMEZ 40 mg: Blisters 14, 28, 30 or 100; white HDPE bottles 30, 100 or 500.
FAQs
Can I take OMEZ during pregnancy or while breastfeeding?
Safety has not been established. Speak to your doctor before using OMEZ if you are pregnant, planning a pregnancy, or breastfeeding.
When should I take OMEZ—morning or evening?
OMEZ is recommended in the morning. Swallow whole with half a glass of liquid.
Can I open, crush, or chew the capsules?
No. Capsules should be swallowed whole. Do not crush or chew the enteric-coated pellets.
How long should I take OMEZ for reflux or ulcers?
For most ulcers and reflux, adults take 20 mg once daily for 4–8 weeks (duodenal ulcers may be 2–4 weeks). Your doctor will advise the exact duration.
What if my reflux symptoms aren’t better after 2 weeks on 20 mg?
If 20 mg daily for 2 weeks does not control symptoms, further investigation is recommended.
Is OMEZ used with antibiotics for H. pylori?
Yes. For H. pylori-positive duodenal ulcers, OMEZ is used as part of an eradication programme with appropriate antibiotics.
I take NSAIDs for pain. Can OMEZ help protect my stomach?
Yes. OMEZ treats NSAID-associated gastric/duodenal lesions (20 mg daily) and can be used for prevention while you are on NSAIDs (20 mg daily).
Can OMEZ affect other medicines?
Yes. Important interactions include clopidogrel (activation reduced), warfarin/phenytoin (may need monitoring and dose changes), digoxin (exposure slightly increased), nelfinavir (contraindicated), atazanavir (not recommended), tacrolimus and methotrexate (levels may rise), and some medicines that need stomach acid for absorption (e.g., ketoconazole, itraconazole, posaconazole, erlotinib). Always check with your pharmacist or doctor.
Can OMEZ cause low magnesium or bone problems?
Long-term/high-dose PPI use has been linked to low magnesium and a small increase in fracture risk. Your clinician may monitor magnesium, especially if you also take digoxin or diuretics, and will aim for the lowest effective dose.
What should I do if I develop persistent diarrhoea?
Contact your doctor. OMEZ use has been associated (frequency not known) with Clostridium difficile-associated diarrhoea, particularly in hospitalised patients.
Does OMEZ affect tumour marker tests like Chromogranin A?
Yes. OMEZ can increase CgA and interfere with tests for neuroendocrine tumours. Stop for at least 5 days before testing; if still raised, repeat 14 days after stopping.
