Omeprazole, Lansoprazole & Esomeprazole Compared: Which PPI Is Right for You?
In This Article
- What are PPIs and how do they work?
- Acid reflux and GORD in the UK
- Omeprazole: uses, doses, and side effects
- Lansoprazole: uses, doses, and side effects
- Esomeprazole: uses, doses, and side effects
- Head-to-head comparison table
- Which PPI should you take?
- Drug interactions to be aware of
- When to seek urgent help
- Frequently asked questions
What Are PPIs and How Do They Work?
Proton pump inhibitors (PPIs) are the most effective class of medicines available for reducing stomach acid. They work by blocking a specific enzyme — the H⁺/K⁺-ATPase “proton pump” — in the cells lining the stomach wall. This irreversibly shuts down acid production until the stomach generates new pump molecules, which is why a single daily dose provides around-the-clock acid suppression.
Omeprazole, lansoprazole, and esomeprazole are the three PPIs most commonly prescribed in UK primary care. Although they work through the same mechanism, they differ in their chemical structure, how the body processes them, their drug interaction profiles, and in some cases their effectiveness for specific patient groups.
For a full explanation of how PPIs work and their uses, see our guide: What Is a Proton Pump Inhibitor?
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Acid Reflux and GORD in the UK
Acid reflux occurs when stomach acid travels back up through the lower oesophageal sphincter — the ring of muscle that should keep it in place — into the oesophagus. The result is the familiar burning sensation in the chest known as heartburn.
When acid reflux becomes chronic, occurring more than twice a week and causing troublesome symptoms, it is classified as gastro-oesophageal reflux disease (GORD). GORD affects an estimated 20% of the UK adult population and is one of the most common conditions managed in primary care.
For mild or infrequent symptoms, lifestyle changes and over-the-counter antacids (such as Gaviscon) are a reasonable first step. But for persistent or moderate-to-severe symptoms, a PPI is the most clinically effective treatment available. Knowing the differences between omeprazole, lansoprazole, and esomeprazole helps you and your prescriber make the right choice.
To understand what triggers acid reflux and when to seek treatment, read our full guide: Acid Reflux Explained.
Omeprazole: Uses, Doses, and Side Effects
Omeprazole is the most widely prescribed PPI in the UK and is considered a first-line choice for most acid-related conditions. It has been used clinically since the late 1980s and has one of the most extensively studied safety profiles of any medicine in regular use.
What omeprazole is used for
- Gastro-oesophageal reflux disease (GORD) and erosive oesophagitis
- Gastric (stomach) ulcers and duodenal ulcers
- Eradication of Helicobacter pylori as part of triple therapy
- Prevention of NSAID-related gastric damage
- Zollinger-Ellison syndrome
Omeprazole doses
| Indication | Standard dose | Duration |
|---|---|---|
| Heartburn / GORD | 20 mg once daily | 4–8 weeks; review for long-term use |
| Gastric ulcer | 20–40 mg once daily | 4–8 weeks |
| Duodenal ulcer | 20 mg once daily | 4 weeks |
| H. pylori eradication | 20 mg twice daily (with antibiotics) | 7 days |
| NSAID gastroprotection | 20 mg once daily | Duration of NSAID use |
Over-the-counter availability
Omeprazole 20 mg is available without a prescription from UK pharmacies for short-term relief of heartburn in adults aged 18 and over. The MHRA recommends limiting over-the-counter use to two weeks. If symptoms persist or recur, consult a prescriber.
Lansoprazole: Uses, Doses, and Side Effects
Lansoprazole is a well-established PPI that is often considered as an alternative to omeprazole — particularly where patients have experienced side effects with omeprazole, or where the omeprazole-clopidogrel interaction is a concern.
What lansoprazole is used for
- Gastro-oesophageal reflux disease (GORD)
- Gastric and duodenal ulcers
- Helicobacter pylori eradication (combination therapy)
- NSAID-associated ulcer prevention and healing
- Zollinger-Ellison syndrome
Lansoprazole doses
| Indication | Standard dose | Duration |
|---|---|---|
| Heartburn / GORD | 15–30 mg once daily | 4–8 weeks; review for long-term use |
| Gastric ulcer | 30 mg once daily | 8 weeks |
| Duodenal ulcer | 30 mg once daily | 4 weeks |
| H. pylori eradication | 30 mg twice daily (with antibiotics) | 7 days |
| NSAID gastroprotection | 15–30 mg once daily | Duration of NSAID use |
Lansoprazole is available as both capsules and orodispersible tablets (Zoton FasTab), which dissolve on the tongue — a useful option for people who have difficulty swallowing capsules.
Esomeprazole: Uses, Doses, and Side Effects
Esomeprazole is the S-isomer of omeprazole — a refined form of the same molecule that may offer more consistent acid suppression in certain patients, particularly those who metabolise omeprazole rapidly. It is often prescribed when patients have not responded adequately to standard-dose omeprazole.
What esomeprazole is used for
- GORD, including erosive oesophagitis healing and maintenance
- Symptom relief of acid reflux in adults
- Helicobacter pylori eradication (combination therapy)
- Prevention of gastric ulcers in patients requiring long-term NSAID treatment
- Pathological hypersecretory conditions including Zollinger-Ellison syndrome
Esomeprazole doses
| Indication | Standard dose | Duration |
|---|---|---|
| Heartburn / GORD (symptom relief) | 20 mg once daily | Up to 4 weeks |
| Erosive oesophagitis healing | 40 mg once daily | 4 weeks (up to 8 if not healed) |
| Erosive oesophagitis maintenance | 20 mg once daily | Long-term, under review |
| H. pylori eradication | 20 mg twice daily (with antibiotics) | 7 days |
| NSAID gastroprotection | 20 mg once daily | Duration of NSAID use |
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Head-to-Head Comparison Table
The following table summarises the key differences between omeprazole, lansoprazole, and esomeprazole to help guide the prescribing decision.
| Feature | Omeprazole | Lansoprazole | Esomeprazole |
|---|---|---|---|
| Brand name | Losec | Zoton FasTab | Nexium |
| Typical GORD dose | 20–40 mg once daily | 15–30 mg once daily | 20–40 mg once daily |
| Available OTC? | Yes (20 mg, up to 2 weeks) | Yes (15 mg, up to 2 weeks) | Yes (20 mg, up to 2 weeks) |
| Formulations | Capsules, dispersible tablets | Capsules, orodispersible tablets | Tablets, sachets |
| Clopidogrel interaction | Significant — avoid if possible | Moderate — use with caution | Significant — avoid if possible |
| Evidence in pregnancy | Most evidence — generally preferred | Limited evidence | Limited evidence |
| Liver metabolism | CYP2C19 (variable) | CYP2C19 + CYP3A4 | CYP2C19 (more consistent) |
| Evidence base | Extensive (30+ years) | Extensive | Strong, more recent |
| Typical use case | First-line for most patients | Alternative when omeprazole unsuitable | When standard PPI has failed; severe GORD |
Which PPI Should You Take?
For most people with acid reflux or GORD, omeprazole is the appropriate first-line choice. It has the longest track record, the most evidence supporting its use across a wide range of conditions, and is the most studied PPI in pregnancy.
Lansoprazole is a sensible alternative when omeprazole is not suitable — for example, if a patient has experienced side effects with omeprazole, or if the omeprazole-clopidogrel drug interaction is a concern. It is also available in an orodispersible form, which is helpful for people who find swallowing capsules difficult.
Esomeprazole is generally reserved for patients whose symptoms have not responded adequately to standard-dose omeprazole, or for those with more severe erosive oesophagitis who may benefit from its more consistent pharmacokinetics. It produces a slightly more predictable level of acid suppression in individuals who metabolise omeprazole rapidly due to genetic variation.
NICE Guidance
NICE recommends omeprazole or lansoprazole as the first-line PPI choices in primary care for most indications including GORD and peptic ulcer management. Prescribers should use the cheapest appropriate PPI for the indication and review ongoing need regularly.
Common side effects shared by all three PPIs
- Headache
- Diarrhoea or constipation
- Nausea, stomach pain, or flatulence
- Skin rash
These are usually mild and resolve without treatment. If side effects persist, switching to a different PPI within the class may help, as individual responses can vary.
Drug Interactions to Be Aware Of
All three PPIs are processed primarily by the liver enzyme CYP2C19. This creates the potential for interactions with other medicines that rely on the same pathway. The most clinically significant interactions are listed below.
Important: Clopidogrel Interaction
Omeprazole and esomeprazole can significantly reduce the antiplatelet effect of clopidogrel by inhibiting its conversion to its active form. If you take clopidogrel, your prescriber may recommend lansoprazole or pantoprazole as safer alternatives. Always inform your prescriber and pharmacist of all medicines you take.
- Anticoagulants (warfarin) — PPIs may increase anticoagulant effect; INR monitoring is advisable
- Clopidogrel — omeprazole and esomeprazole may reduce antiplatelet efficacy
- Antifungals (ketoconazole, itraconazole) — reduced absorption due to lower gastric acidity
- Methotrexate — PPIs may increase methotrexate plasma levels
- HIV medicines (atazanavir, nelfinavir) — reduced absorption; avoid PPI co-administration
- Levothyroxine — absorption may be affected; take levothyroxine at a separate time
When to Seek Urgent Help
Red Flag Symptoms — Seek Immediate Medical Advice
Do not delay seeking medical attention if you experience any of the following: unexplained weight loss, persistent difficulty swallowing (dysphagia), vomiting blood, passing black or tarry stools, or severe and worsening upper abdominal pain. These can be signs of a serious underlying condition that requires urgent investigation. If you are over 55 and develop new or changing dyspepsia symptoms, see a doctor promptly.
If your symptoms do not improve after four weeks of PPI treatment, or if they return repeatedly, consult a prescriber. You may need further investigation or a different treatment approach.
Get Your Acid Reflux Treatment Online
Access Doctor offers safe, regulated online consultations for acid reflux and GORD. Our GPhC-registered pharmacist independent prescribers can assess your symptoms and issue a prescription — including omeprazole, lansoprazole, or esomeprazole where clinically appropriate — with next-day delivery available.
Acid Reflux Treatment
Omeprazole
First-line PPI for GORD, heartburn, and gastric ulcers. Available on prescription following a quick online clinical assessment.
Consult & prescribeAcid Reflux Treatment
Lansoprazole
Effective PPI alternative — often preferred where omeprazole is not suitable. Prescribed following a regulated online assessment.
Consult & prescribeReady to find the right acid reflux treatment? Start a safe, confidential consultation with Access Doctor. Our regulated clinical team will assess your symptoms and prescribe the most appropriate PPI for you — with next-day delivery available across the UK.
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Medical Disclaimer: This article is intended for informational purposes only and does not constitute medical advice. It should not be used to diagnose or treat any health condition. Always consult a qualified healthcare professional before starting, stopping, or changing any medication. Prescriptions issued through Access Doctor are provided by GPhC-registered pharmacist independent prescribers following a clinical assessment. Access Doctor is a GPhC-registered pharmacy (registration number 9011198).
Frequently Asked Questions
Which is better: omeprazole or lansoprazole?
Both omeprazole and lansoprazole are effective PPIs for treating acid reflux and GORD. Omeprazole tends to produce slightly greater overall acid suppression and has been in clinical use longer. Lansoprazole may be preferred in patients who have experienced side effects with omeprazole, or where the omeprazole-clopidogrel drug interaction is a concern. In practice, most people respond equally well to either, and your prescriber will choose based on your individual circumstances.
Is esomeprazole stronger than omeprazole?
Esomeprazole is the S-isomer of omeprazole and may produce more consistent acid suppression in some patients — particularly those who metabolise omeprazole quickly. However, the clinical difference in effectiveness for most people is modest. Esomeprazole is not universally “stronger” and is generally used when patients have not responded adequately to standard-dose omeprazole.
Can I switch from omeprazole to lansoprazole?
Yes, switching between PPIs is generally straightforward and safe. Because all PPIs work through the same mechanism, you can usually switch directly without a break. You should always do this under the guidance of a prescriber, who can advise on the equivalent dose and the most suitable option for your circumstances.
What is the standard dose of omeprazole for acid reflux?
The standard prescription dose of omeprazole for acid reflux (GORD) in adults is 20 mg once daily, taken in the morning before food. For more severe or persistent symptoms, a prescriber may increase this to 40 mg once daily. Over-the-counter omeprazole 20 mg is available for short-term treatment of heartburn for up to two weeks.
Do omeprazole, lansoprazole, and esomeprazole have the same side effects?
Yes, all three share a broadly similar side effect profile. Common side effects include headache, diarrhoea, constipation, nausea, and stomach pain. Rare but serious effects — such as low magnesium, vitamin B12 deficiency with long-term use, and Clostridium difficile infection — can occur with any PPI. If you experience troublesome side effects with one PPI, switching to another in the class may help, as individual responses can vary.
Which PPI has the fewest drug interactions?
Pantoprazole and rabeprazole are generally considered to have fewer significant drug interactions than omeprazole, lansoprazole, or esomeprazole, because they are metabolised differently by the liver. Omeprazole in particular can reduce the effectiveness of clopidogrel — this interaction is less pronounced with lansoprazole. If you take multiple medicines, your prescriber will choose a PPI with the lowest interaction risk for your specific situation.
References
- National Institute for Health and Care Excellence (NICE). Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management. Clinical guideline CG184. 2014 (updated 2019). nice.org.uk/guidance/cg184
- National Institute for Health and Care Excellence (NICE). Dyspepsia — proven GORD: prescribing a proton pump inhibitor. NICE CKS. 2024. cks.nice.org.uk
- Guts UK. Heartburn and reflux. Patient information. gutscharity.org.uk
- Lanza FL, Chan FKL, Quigley EMM; Practice Parameters Committee of the American College of Gastroenterology. Guidelines for prevention of NSAID-related ulcer complications. American Journal of Gastroenterology. 2009;104(3):728–38.
- Medicines and Healthcare products Regulatory Agency (MHRA). Omeprazole and esomeprazole: interaction with clopidogrel. Drug Safety Update. 2010. gov.uk/drug-safety-update