--- title: "Omeprazole and PPIs: Uses & Side Effects | HealthAnswers" description: "Omeprazole is a proton pump inhibitor (PPI) that reduces stomach acid for heartburn, reflux and ulcers; how to take it safely and when to see a GP." url: https://healthanswers.co.uk/treatments/omeprazole-and-ppis/ robots: noindex --- # Omeprazole and PPIs: Uses & Side Effects | HealthAnswers Treatments Omeprazole is a proton pump inhibitor (PPI) that reduces stomach acid for heartburn, reflux and ulcers; how to take it safely and when to see a GP. Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026 ## Quick answer What are omeprazole and PPIs used for? Omeprazole is a proton pump inhibitor (PPI), a medicine that reduces stomach acid to treat heartburn, acid reflux and stomach ulcers, and to protect the stomach when taking anti-inflammatory medicines. It is available on prescription and from pharmacies, and works best taken 30 to 60 minutes before food. Short courses treat symptoms, while long-term use needs periodic GP review. ## Who is this page for? This page is for people in the UK who want a plain-English overview of Omeprazole and PPIs, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally. ## Who should skip this page? Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland. On this page 10 sections ## Key facts about omeprazole and PPIs - PPIs block acid production in the stomach and last longer than antacids or H2 blockers. - Omeprazole is available from pharmacies for short courses to treat heartburn. - PPIs work best taken before food, usually in the morning before breakfast. - Long-term PPI use may affect magnesium and B12 levels and bone fracture risk. - PPIs can mask stomach cancer symptoms, so see a GP for swallowing difficulty or weight loss. ## What are PPIs? Proton pump inhibitors (PPIs) are medicines that block acid production in the lining of the stomach. They are used to treat heartburn, GORD (acid reflux), stomach and duodenal ulcers, and to protect the stomach when taking NSAIDs such as ibuprofen or naproxen, or aspirin, long term. Omeprazole and lansoprazole are the most commonly used PPIs in the UK. Both are available on NHS prescription and over the counter from pharmacies for short courses. ## How PPIs work Cells in the stomach lining, called parietal cells, use a proton pump to produce hydrochloric acid. PPIs block this pump, so acid levels fall significantly for around 24 hours after each dose. Antacids work by instantly neutralising acid that is already there, while H2 blockers such as ranitidine (now largely withdrawn) reduce acid production by a different route. PPIs provide stronger and more sustained acid suppression than either, which makes them better at healing erosive oesophagitis and ulcers. ## What PPIs treat PPIs are used for a range of conditions linked to excess stomach acid. These include GORD and heartburn, where acid refluxes into the oesophagus; peptic ulcers, often alongside antibiotics that clear H. pylori infection; and prevention of ulcers in people who need to take NSAIDs long term. They are also used for the rare Zollinger-Ellison syndrome and for Barrett’s oesophagus, where long-term acid suppression can reduce the risk of the condition progressing. ## How to take a PPI PPIs work best when taken 30 to 60 minutes before food, usually in the morning before breakfast. Tablets should be swallowed whole rather than crushed, unless a dispersible formulation is prescribed. Most people take a PPI once daily, though twice-daily dosing is sometimes used for severe oesophagitis or Zollinger-Ellison syndrome. Over-the-counter courses are intended to last no more than two weeks without seeing a GP; if symptoms keep returning, it is better to see a GP than to repeat short courses indefinitely. ## Side effects and long-term considerations In the short term, PPIs can cause headache and mild stomach upset, but these are usually mild and settle quickly. With months or years of use, there are small increased risks that are worth being aware of. These include fractures of the hip, wrist or spine, particularly with high doses, in older people, or in those with existing osteoporosis; C. difficile diarrhoea; low magnesium levels (hypomagnesaemia), which can rarely cause muscle cramps or an irregular heartbeat; vitamin B12 deficiency with very long-term use; and an association with kidney disease seen in observational studies, though this has not been proven to be caused by PPIs. For genuine indications, the benefits of taking a PPI usually outweigh these risks, but regular review helps ensure the dose is reduced or stopped once it is no longer needed. ## Rebound acid hypersecretion After months of PPI use, stopping abruptly can cause a temporary surge in acid production, worsening heartburn for days to weeks. This is not addiction but a physiological rebound effect. A GP can suggest a tapering strategy, such as reducing the dose gradually or moving to alternate-day dosing before stopping completely, using antacids or an H2 blocker briefly if needed to manage symptoms. ## When symptoms need urgent investigation, not just a PPI PPIs can relieve symptoms that are also warning signs of stomach cancer, so it is important not to let them delay diagnosis. See a GP promptly for difficulty swallowing, unexplained weight loss, persistent vomiting, blood in vomit or black stools, anaemia, or new symptoms appearing for the first time over the age of 55. If symptoms do not improve after a short PPI trial, a GP may refer you for a gastroscopy to look inside the stomach. ## Interactions with other medicines Omeprazole and esomeprazole may reduce how well clopidogrel is activated in the body, though how significant this is clinically remains debated, and pantoprazole is sometimes chosen instead when both medicines are needed. PPIs may also increase levels of methotrexate, so this combination needs monitoring. Some drugs that rely on stomach acid for absorption, such as ketoconazole, itraconazole and iron, need their timing separated from a PPI dose. St John’s wort and rifampicin can reduce PPI levels in the body. ## PPIs compared with lifestyle changes for reflux For mild GORD, lifestyle changes are usually tried first. These include losing weight if you are overweight, raising the head of the bed, avoiding late meals, alcohol and other trigger foods, and stopping smoking. A PPI is generally used when lifestyle changes are not enough on their own, or when there is erosive disease visible on endoscopy. ## When long-term PPI use is essential Some conditions justify long-term PPI use as standard care, including Barrett’s oesophagus, severe oesophagitis, an ongoing need for NSAIDs in someone with a history of ulcers, and Zollinger-Ellison syndrome. In these cases, a GP will typically monitor bone health and magnesium levels and review the dose periodically. PPIs are effective and widely used medicines. The key to using them safely is matching the right indication with the right duration, and having GP review rather than repeating over-the-counter courses indefinitely without further investigation. ## ! Important safety information for omeprazole and PPIs See a GP if heartburn persists after 2 weeks of an over-the-counter PPI, or if you have difficulty swallowing, unexplained weight loss, vomiting blood, or black tarry stools. If you take a PPI long-term, ask for an annual review to check whether you can move to the lowest effective dose. Seek **urgent** help for severe chest pain, as this could be a heart attack rather than indigestion. ## Common questions about omeprazole and PPIs What is the difference between omeprazole and lansoprazole? Omeprazole and lansoprazole are both PPIs with similar effectiveness, so the choice between them often comes down to cost and how an individual responds. Omeprazole is usually taken once daily, and lansoprazole may suit people who do not respond well to omeprazole. Esomeprazole and pantoprazole are further alternatives. Can I take omeprazole long term? Many people take PPIs such as omeprazole for months or years for conditions like GORD or Barrett's oesophagus, under GP supervision. Long-term use carries small increased risks, including fractures, C. difficile infection, and magnesium or B12 deficiency, but the benefits usually outweigh these risks for genuine indications. Regular review helps ensure you stay on the lowest effective dose. What are the side effects of omeprazole? Common side effects of omeprazole include headache, nausea, diarrhoea, constipation and stomach pain, and these are usually mild. With long-term use, there is an increased risk of fractures, an association with kidney disease seen in observational studies, and a risk of low magnesium levels. Serious allergic reactions are rare. Can I stop taking omeprazole suddenly? Stopping a PPI suddenly after long-term use can cause a rebound surge in acid, temporarily worsening heartburn for days to weeks. It is usually better to taper the dose gradually, for example by alternating days before stopping, and to seek GP advice if symptoms return severely. Do PPIs interact with other medicines? Yes, PPIs can reduce the absorption of some drugs that need stomach acid, such as ketoconazole and iron. There is also debate about whether omeprazole reduces the effectiveness of clopidogrel, which is why pantoprazole is sometimes preferred if both are needed. Always tell your GP and pharmacist about all your medicines, including anything bought over the counter. ## Sources - [NHS — Omeprazole](https://www.nhs.uk/medicines/omeprazole/) - [NICE — Dyspepsia and GORD](https://www.nice.org.uk/guidance/cg184)