Omeprazole: Uses, Dosage, Side Effects and Precautions

At a Glance

What Is Omeprazole?

Omeprazole is a proton pump inhibitor (PPI) that reduces the amount of acid your stomach makes. Doctors prescribe it for acid-related conditions such as GERD, peptic ulcers and acid reflux.

How Omeprazole Works

Omeprazole inhibits the H+/K+ ATPase pump in the stomach’s acid-producing cells. This lowers gastric acid secretion and helps relieve heartburn, acid regurgitation and stomach pain linked to reflux and ulcers.

Uses of Omeprazole

• GERD: treats heartburn and acid reflux, and erosive oesophagitis (damage to the food pipe caused by acid). The US label also covers maintaining healing of erosive oesophagitis.

• Peptic ulcers: heals active duodenal ulcers and benign gastric ulcers.

• H. pylori infection: used together with antibiotics (combination therapy). Treating H. pylori reduces the chance of a duodenal ulcer coming back.

• Pathological hypersecretory conditions, such as Zollinger-Ellison syndrome (US label).

• Children: the NHS lists discomfort from severe reflux in children. The US label covers GERD from age 1 and erosive oesophagitis from age 1 month.

Omeprazole Dosage and How to Take It

The dose depends on the condition, age, weight, the form used, liver function and treatment response. The figures below summarize the US prescribing information for Prilosec (revised 12/2016) and are not a personal dose. The NHS gives no specific doses.

Adults (US label)

• Active duodenal ulcer: 20 mg once daily for 4 weeks

• Active benign gastric ulcer: 40 mg once daily for 4–8 weeks

• Symptomatic GERD: 20 mg once daily for up to 4 weeks

• Erosive oesophagitis: 20 mg once daily for 4–8 weeks. Maintenance is 20 mg once daily, and controlled studies do not extend beyond 12 months.

• H. pylori: omeprazole 20 mg with amoxicillin and clarithromycin, all twice daily for 10 days. An alternative is omeprazole 40 mg once daily with clarithromycin for 14 days.

• Zollinger-Ellison syndrome: the starting dose is 60 mg once daily, adjusted to the patient.

• The label lowers the maintenance dose to 10 mg for hepatic impairment or Asian patients.

Children aged 1–16 (US label, once daily)

5 mg (5 to under 10 kg), 10 mg (10 to under 20 kg) or 20 mg (20 kg and over), for up to 4 weeks (symptomatic GERD) or 4–8 weeks (erosive oesophagitis). Infants have separate weight-based doses.

How to take it

• The US label says to take it before meals. The NHS says it can be taken with or without food, once daily in the morning or twice daily morning and evening.

• Swallow capsules and tablets whole with water. Do not chew or crush those labelled “enteric coated” or “gastro-resistant” (NHS).

• If you miss a dose, take it when you remember unless the next dose is nearly due. Never take two doses together (NHS).

• Without a prescription, do not take omeprazole for longer than 2 weeks (NHS). See a doctor if symptoms persist or worsen.

Take this medicine only as advised by your doctor or healthcare professional. Do not start, stop, or change the dose on your own.

Side Effects of Omeprazole

Common

• Headache

• Stomach pain

• Nausea or vomiting

• Diarrhoea or constipation

• Wind (flatulence)

Rare but serious (the risk may be higher with use of a year or more)

• Low vitamin B12, causing tiredness, dizziness, or muscle twitching or weakness

• Weakened bones that break more easily

• Low magnesium levels (rare, US label)

• Severe or persistent diarrhoea, which may be a C. difficile infection (US label)

• Acute interstitial nephritis, a kidney inflammation (US label)

• Lupus, causing rashes in sun-exposed skin and joint pain

Contact your doctor promptly if you think you have a serious side effect. Get emergency help for signs of a severe allergic reaction, such as swelling of the throat or tongue, a raised itchy rash or difficulty breathing.

Contraindications and Precautions

Contraindications (US label)

• Hypersensitivity to omeprazole, other substituted benzimidazoles or any component of the product

• Use with rilpivirine-containing medicines

Precautions

• Masking serious illness: a good response to omeprazole does not rule out stomach cancer. The NHS notes it can mask symptoms of serious conditions. Tell your doctor about warning signs such as unexplained weight loss, trouble swallowing or vomiting blood.

• Kidney or liver conditions and osteoporosis: tell your doctor before starting (NHS).

• Long-term use: the US label warns of bone fractures with long-term or high-dose use and of vitamin B12 deficiency. Your doctor decides how long you need treatment.

• Tests: omeprazole can raise chromogranin A (CgA) levels, so the US label advises stopping it at least 14 days before CgA testing. The NHS says to check with the clinic before other planned tests.

• Alcohol: best avoided, as it can raise stomach acid and worsen symptoms (NHS).

Drug Interactions

• Clopidogrel (US label, NHS): the label advises avoiding concomitant use.

• St John’s Wort and rifampin (US label): avoid, as they can lower omeprazole levels.

• Rilpivirine (US label): contraindicated.

• Atazanavir and nelfinavir (US label, NHS): omeprazole can reduce their levels.

• Methotrexate (US label): levels may rise, especially with high doses.

• Warfarin (US label, NHS): INR may rise, so monitoring is advised.

• Digoxin, phenytoin, diazepam, citalopram, cilostazol and mycophenolate (US label; digoxin, phenytoin and diazepam also NHS): effects can change.

The NHS also asks you to check before combining omeprazole with lansoprazole or famotidine. Tell your doctor or pharmacist about all prescription and OTC medicines, supplements and herbal products you use. This list is not complete.

Omeprazole in Pregnancy and Breastfeeding

• Pregnancy: the NHS says omeprazole can usually be taken, but check with a pharmacist or doctor first. The US label says human data are limited and have not shown a clear increase in major malformations. Animal studies showed embryo toxicity at high doses.

• Breastfeeding: the NHS says it can usually be taken while breastfeeding, and side effects in breastfed babies are rare. The US label says omeprazole may be present in breast milk. Discuss it with your doctor.

Omeprazole Brands and Price in India

• The Omez listing said the product is discontinued, and the Omee listing showed it out of stock.

• These are online retail listings and do not confirm regulatory status or current availability. Selling prices include discounts and change by pharmacy, location and date. Confirm with your pharmacist.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have questions about this medicine, its side effects, or your treatment plan, you can consult a doctor through HealthPil.