Yes. It may be possible to switch from omeprazole to esomeprazole without a washout period, but any change in treatment should be agreed with your prescriber. The most appropriate timing and dose will depend on your individual circumstances.
Esomeprazole is closely related to omeprazole because it contains one of the two isomers found in omeprazole. For adults in the UK using or considering proton pump inhibitors (PPIs) for acid reflux, GORD, or stomach ulcers, this relationship helps explain common questions about switching between the two medicines, how they compare in terms of effectiveness, dosing, cost, storage, and when one may be considered more appropriate than the other.
This page provides general information only and does not recommend a specific medicine, dose, or treatment. Treatment suitability depends on an individual clinical assessment by a UK registered prescriber.
The Actual Difference: Chemistry, Not Just Branding
Omeprazole is a racemic mixture, which means it contains two mirror image forms of the same molecule, known as the R and S enantiomers. Esomeprazole contains only the S enantiomer of omeprazole. This is why esomeprazole is sometimes described as a more purified form of omeprazole rather than a completely different medicine.
In practice, this means:
- Both medicines work in the same way by blocking the hydrogen potassium ATPase enzyme, often called the "proton pump", in the lining of the stomach. This reduces the amount of stomach acid produced.
- Esomeprazole is processed slightly differently by the body and may produce more consistent blood levels in some people.
- For most people with acid reflux or GORD, the clinical differences are small. Both medicines are widely used proton pump inhibitors (PPIs), and neither is considered generally superior. The most appropriate choice depends on your symptoms, medical history, other medicines you take, and your prescriber's clinical judgement.
Effectiveness and Onset in Gastro-oesophageal Reflux Disease (GORD)
Both medicines are used to treat GORD (gastro oesophageal reflux disease) and may begin to improve symptoms within a few days, although the full effect is often seen after around one week of regular use.
Esomeprazole and omeprazole are processed slightly differently by the body, but for most people this does not result in a meaningful difference in treatment outcomes.
Some studies have suggested that esomeprazole may provide slightly higher healing rates for erosive oesophagitis in certain groups of patients. However, the overall differences are generally small, and both medicines are widely used and considered effective treatment options. The most appropriate choice depends on your individual circumstances and your prescriber's clinical judgement.
Flag for clinical review: Any specific healing rate or acid suppression percentages should be verified against the current British National Formulary (BNF) and Summary of Product Characteristics (SmPC) before publication. Where evidence varies, it is generally preferable to describe the medicines as having broadly similar effectiveness rather than quoting unsupported figures.
Dosing Reference (General Information)
The table below reflects commonly used adult dosing ranges described in prescribing guidance and product information . This is general reference information, not a recommendation for your own dose, your prescriber determines what's appropriate for you.
| Omeprazole | Esomeprazole | |
|---|---|---|
| Typical starting dose | 20mg once daily | 20mg once daily |
| Typical range | Up to 40mg daily for some conditions | 20–40mg daily depending on condition |
| Timing | Usually taken before food, in accordance with prescribing instructions and the patient information leaflet | Before food, generally in the morning |
| Swallowing | Capsules shouldn't be crushed or chewed | Tablets shouldn't be crushed or chewed |
| Typical course | 4–8 weeks for initial healing | 4–8 weeks for initial healing |
Switching Between Omeprazole and Esomeprazole
Your prescriber may suggest switching between omeprazole and esomeprazole for several reasons, including if your symptoms are not well controlled, you experience side effects, or there are cost or prescribing considerations.
Because both medicines belong to the same class of medicines, switching between them is often straightforward and may not require a washout period. However, the most appropriate approach will depend on your individual circumstances and should be decided by your prescriber.
It is also important to allow enough time to assess how well the new medicine is working. While some people notice an improvement within a few days, it may take 2 to 4 weeks to fully assess the effect of treatment.
This information is provided as general guidance only and is not an instruction to change your treatment. Any switch should be discussed with your prescriber or pharmacist, who can advise on the most appropriate approach and whether a dose adjustment is needed.
Storage Guidance
Proper storage helps medicines remain suitable for use throughout their shelf life.
- Temperature: Follow the storage instructions provided with your specific product. Store your medicine in a cool, dry place, such as a bedroom drawer or kitchen cupboard away from direct heat. Avoid storing it in places where temperature and humidity can vary, such as the bathroom or inside a car.
- Packaging: Keep your medicine in its original packaging unless your healthcare professional advises otherwise.
- Moisture: Protect your medicine from moisture. If the packaging is damaged or the medicine appears discoloured, soft, or different from normal, do not use it. Contact your pharmacy for advice.
- Shelf life: Always check the expiry date printed on the packaging before using your medicine.
- Travelling: When flying, keep your medicine in its original packaging in your hand luggage to help protect it from extreme temperatures.
This is general storage guidance. Always follow the instructions provided in the Patient Information Leaflet supplied with your medicine, as these take precedence if they differ.
Cost Comparison
| Treatment | From (price) |
|---|---|
| Omeprazole 20mg Capsules | £12.99 |
| Losec MUPS 20mg Tablets (branded omeprazole) | £29.99 |
| Esomeprazole Tablets | £16.99 |
| Pantoprazole 20mg Tablets | £5.99 |
| Lansoprazole 15mg Capsules | £5.99 |
| Rabeprazole | £19.99 |
| Famotidine Tablets (H2 blocker, non-PPI option) | £8.49 |
Generic omeprazole is often the lower cost option and has been widely used in clinical practice for many years. The price of esomeprazole may vary depending on the supplier, formulation, and current market conditions. Brand names, such as Nexium, may also affect pricing.
Cost is only one factor when choosing between these medicines. Your prescriber will also consider your symptoms, medical history, other medicines you take, and overall clinical suitability. For many people, the clinical differences between omeprazole and esomeprazole are small.
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Which Should You Choose?
Your prescriber will consider several factors when deciding whether omeprazole or esomeprazole is the most appropriate option for you, including your symptoms, medical history, and current medicines.
- If cost is an important consideration: If omeprazole has worked well for you previously, your prescriber may consider it an appropriate option. Generic omeprazole is often the lower cost choice.
- If you have tried omeprazole without enough symptom relief: Your prescriber may consider esomeprazole or another suitable treatment. Individual responses vary, so one medicine is not guaranteed to work better than another.
- If you take other regular medicines: Tell your prescriber about all the medicines you take. They will review any potential medicine interactions before recommending a treatment.
- If you may need longer term treatment: Your prescriber will review the benefits and potential risks of ongoing treatment. Long term use of proton pump inhibitors has been associated with risks such as low magnesium levels, vitamin B12 deficiency, bone fractures, and, rarely, kidney problems. Regular clinical review helps ensure treatment remains appropriate.
- If you experience side effects: Some people may experience side effects such as dizziness or blurred vision while taking esomeprazole. If side effects affect your daily activities or are persistent, speak to your prescriber or pharmacist.
Your prescriber will recommend the most appropriate treatment based on your individual health needs and current medicines.
