Omeprazole: Uses, How It Works, Medicines
Omeprazole is a proton pump inhibitor (PPI), a medicine that lowers the amount of acid the stomach makes. It is used to treat acid reflux (GERD), heartburn and acidity, and to help stomach and duodenal ulcers heal. Together with antibiotics, it is also used to treat Helicobacter pylori infection. In India it is a prescription medicine.
Also known as: Omeprazole 20 mg, Omeprazole capsule, Omeprazole IP, Omeprazole delayed-release, Proton pump inhibitor, PPI, Acidity capsule
Pharmacist review in progress. This page is based on the sources listed below and is being checked by our registered pharmacist.
How does Omeprazole work?
Omeprazole is switched on by the acid inside the stomach's acid-making cells and then binds firmly to their proton pumps, so they stop releasing acid. The body has to make new pumps to restore acid production, so one dose keeps acid low for about a day.
How to take Omeprazole
Follow the label or your doctor's advice. Omeprazole is usually taken once a day before breakfast, swallowed whole, and the strength and number of weeks depend on the condition being treated. Ask your doctor to review it if you have been taking it for months.
Side effects of Omeprazole
Most people take omeprazole without problems, and side effects are usually mild. A few rare risks are linked mainly to using it for a year or more.
Uncommon or mild
- Headache
- Stomach pain
- Feeling sick (nausea) or being sick (vomiting)
- Constipation or diarrhoea
- Wind (gas)
- Dizziness
Rare but serious: get medical help
- Signs of a severe allergic reaction: swelling of the face, lips or throat, difficulty breathing, or a sudden widespread rash
- A serious skin reaction: red skin with blisters or peeling, sores in the mouth, or a widespread rash with fever. Get medical help immediately
- Watery or bloody diarrhoea that does not go away, with stomach cramps or fever, which can be a sign of a gut infection called C. difficile
- Passing less urine, blood in the urine, fever, rash or pain in the lower back, which can be signs of kidney inflammation
- A rash on skin exposed to the sun, especially with joint pain, which can be a sign of a lupus-type reaction
- Very low vitamin B12 (tiredness, tingling, a sore tongue) or weak bones, mainly after long-term use
- Muscle cramps or twitching, shaking, an irregular heartbeat or confusion, which can be signs of low magnesium, mainly after several months of use
Who should be careful
Omeprazole can ease symptoms that come from a more serious problem, and it can cause problems when taken for a long time. Some people need a doctor's check first.
When the label says not to use it
- Allergy to omeprazole, other proton pump inhibitors (substituted benzimidazoles) or any ingredient of the capsule
- Treatment with the HIV medicine rilpivirine, unless your doctor advises otherwise
- Warning signs that need a doctor's check first: unexplained weight loss, difficulty or pain when swallowing, repeated vomiting, vomiting blood, or black stools. Omeprazole can ease symptoms and hide a more serious problem such as stomach cancer
- Long-term use (especially a year or more): it can lower vitamin B12, weaken bones and slightly raise the risk of fractures and gut infections. Your doctor may review whether you still need it
- If you bought omeprazole without a prescription, do not take it for longer than 2 weeks without seeing a doctor
- Low magnesium, or taking water tablets (diuretics) or digoxin: your doctor may check magnesium levels
- Weak bones (osteoporosis), kidney disease or liver disease: tell your doctor first
- A planned endoscopy or tests for neuroendocrine tumours (chromogranin A): omeprazole may need to be paused for some time beforehand, so tell the doctor doing the test
- Pregnancy or breastfeeding: omeprazole is often considered usable, but ask your doctor or pharmacist first
- Past allergic reaction to omeprazole or similar medicines such as pantoprazole, esomeprazole or rabeprazole
Medicines and things that interact with Omeprazole
Omeprazole lowers stomach acid and is broken down by liver enzymes, so it can change how some medicines work. Tell your doctor or pharmacist about everything you take.
- Clopidogrel (a blood thinner used after heart attacks or stents): omeprazole can make it less effective, so your doctor may choose a different acid-lowering medicine
- Warfarin and similar blood thinners: clotting tests (INR) may be needed more often
- Phenytoin and diazepam: omeprazole can slow their clearance, so their effect may be stronger
- Digoxin, tacrolimus and methotrexate: levels can rise, so your doctor may check them
- HIV medicines atazanavir, nelfinavir and rilpivirine: omeprazole can sharply lower their levels. Your doctor will decide if the combination is acceptable
- Medicines that need stomach acid to be absorbed, such as ketoconazole, itraconazole and iron tablets: they may work less well
- Voriconazole: it can raise omeprazole levels
- St John's wort and rifampicin: they may lower omeprazole levels
- Other acid-lowering medicines such as lansoprazole or famotidine: ask your doctor before combining
Effects on lab tests
- Chromogranin A blood test (used to look for neuroendocrine tumours): levels can rise and give a false positive
- Tests such as endoscopy: omeprazole may need to be paused beforehand, as your doctor advises
If someone takes too much
Taking one extra capsule by mistake is unlikely to cause harm. If someone has taken much more than prescribed, or feels unwell, call 112 or go to the nearest hospital and take the medicine pack with you.
Regulatory status in India
Approved for sale in India as a prescription medicine. Single-ingredient omeprazole is not on the CDSCO list of banned medicines. Some fixed-dose combinations that include omeprazole are prohibited, for example omeprazole with paracetamol and diclofenac, so check the ingredient list on the pack.
Type of medicine
Omeprazole belongs to this type of medicine.
Medicines that contain Omeprazole
These medicines sold in India contain Omeprazole. They are listed A to Z, not ranked.
- Omez 20 · 20 mg gastro-resistant (enteric-coated) capsule
What is Omeprazole used for?
Medicines that contain Omeprazole are used for these conditions.
Other medicines of the same type
These active ingredients are of the same type as Omeprazole.
Common questions
Is Omez 20 the same as omeprazole?
Omez 20 is a brand name for a capsule that contains 20 mg of omeprazole and nothing else. Other brands and generic capsules contain the same medicine. Check the ingredients and strength on the pack, and ask your pharmacist if you are unsure.
When is omeprazole usually taken?
It is usually taken once a day before breakfast and swallowed whole with water, without crushing or chewing. Some conditions need two doses a day. Follow your doctor's advice or the label.
How long does omeprazole take to work?
Acid output starts falling within hours, but symptoms usually ease over a few days. It is not meant for instant relief of a sudden attack of acidity. Your doctor will say how long to take it.
Is omeprazole an antacid?
No. Antacids neutralise acid already in the stomach and work within minutes for a short time. Omeprazole reduces how much acid the stomach makes, so it works more slowly but lasts about a day. Ask your pharmacist if you want to use both.
What is the difference between omeprazole and pantoprazole or esomeprazole?
All are proton pump inhibitors that lower stomach acid in a similar way. They are different molecules, with different strengths and interactions. Which one suits you is a decision for your doctor, who will also ask about other medicines you take.
Can I take omeprazole every day for a long time?
Only if your doctor advises it and reviews it regularly. Long-term use, especially beyond a year, is linked to low vitamin B12, weaker bones and gut infections. Many people need it only for a few weeks. Ask your doctor before continuing for months.
Does omeprazole interact with other medicines?
Yes. It can affect clopidogrel, warfarin, phenytoin, digoxin, methotrexate and some HIV medicines, and it can reduce absorption of iron and some antifungals. Tell your doctor or pharmacist about everything you take.
Can I take omeprazole during pregnancy or while breastfeeding?
It can often be taken, but check with your doctor or pharmacist first. Do not start or stop it during pregnancy or breastfeeding without your doctor's advice.
Sources
- Omeprazole: a medicine to lower stomach acid. NHS (UK)
- Heartburn and acid reflux. NHS (UK)
- Omeprazole delayed-release capsules: prescribing information (label revised 8/2009, repackager copy). DailyMed, US National Library of Medicine
- PROTONIX (pantoprazole sodium) delayed-release tablets: full prescribing information (revised 6/2023). Pfizer (Wyeth Pharmaceuticals), US FDA-approved labeling
- Omeprazole. StatPearls, NCBI, US National Library of Medicine
- National Formulary of India. Indian Pharmacopoeia Commission
- List of drugs prohibited for manufacture and sale through gazette notifications under section 26A of the Drugs & Cosmetics Act 1940. Central Drugs Standard Control Organisation (CDSCO)
- National List of Essential Medicines 2022. Ministry of Health and Family Welfare, Government of India (copy hosted by CDSCO)