Omeprazole vs Esomeprazole: Dosage Comparison Guide

Omeprazole and esomeprazole are closely related proton pump inhibitors (PPIs) used to reduce stomach acid. For standard PPI dose comparisons, NICE considers esomeprazole 20mg broadly equivalent to omeprazole 20mg. It is not simply a case of doubling the esomeprazole dose to match omeprazole.

The dose you need depends on the condition being treated. For example, 20mg once daily is a standard dose for many adults with GORD, while higher doses are used for conditions such as severe reflux oesophagitis or Zollinger Ellison syndrome. Some specialist conditions can require doses well above the usual reflux doses.

This guide explains how the two medicines compare, what their usual maximum doses look like for different conditions, when switching may make sense and why you should not increase either medicine without medical advice.

Key things to know

• Omeprazole 20mg and esomeprazole 20mg are broadly considered dose equivalent in NICE's standard PPI dosing framework.
• Esomeprazole should not be described simply as a "faster" version of omeprazole. The two medicines are closely related, but individual response can differ.
• For standard acid reflux treatment, doses are generally much lower than the specialist doses used for conditions such as Zollinger Ellison syndrome.
• Omeprazole is a mixture of two isomers, while esomeprazole is the S isomer of omeprazole. This difference affects how the medicines are metabolised, but it does not mean one part of omeprazole is simply "inactive".
• Switching between omeprazole and esomeprazole can usually be done without a complicated taper, but the replacement dose should be confirmed with your prescriber or pharmacist.

Is Omeprazole 20mg Equivalent to Esomeprazole 20mg?

Broadly, yes. NICE's PPI dosing information classifies esomeprazole 20mg as equivalent to omeprazole 20mg for its standard dose framework.

This means there is no general 1:2 rule where you need 40mg of esomeprazole to match 20mg of omeprazole.

There are, however, important differences when you look at higher treatment doses. For severe oesophagitis, for example, NICE uses 40mg once daily as the standard dose for both omeprazole and esomeprazole in its specific severe oesophagitis dosing table. Higher doses may be used in selected cases under medical supervision.

So it is better to think of the two medicines as broadly dose equivalent at standard doses rather than applying a fixed conversion formula to every condition.

Maximum Daily Dose for Each

There is no single maximum daily dose that applies to every person or every condition.

For ordinary acid reflux and GORD, the doses are generally much lower. NICE lists omeprazole 20mg once daily and esomeprazole 20mg once daily as standard doses. For severe oesophagitis, it lists 40mg once daily as the standard dose and 40mg twice daily as the high or double dose.

Zollinger Ellison syndrome is different. Omeprazole treatment commonly starts at 60mg daily and is adjusted according to the person's response. Doses of 20mg to 120mg daily have been used, with doses above 80mg divided into two doses.

For esomeprazole, the licensed product information gives an initial dose of 40mg twice daily for Zollinger Ellison syndrome. The dose is then individually adjusted, with many patients controlled on 80mg to 160mg daily. Doses above 80mg daily are divided into two doses.

These are specialist doses and should not be used as a guide for treating ordinary heartburn or reflux.

Why Esomeprazole Is Not Simply "Faster" Than Omeprazole

You may see esomeprazole described online as a faster or stronger version of omeprazole. That is too simple.

Esomeprazole is the S isomer of omeprazole, while standard omeprazole contains both the R and S isomers. This difference affects how the medicines are handled by the body and contributes to differences in their pharmacokinetic profiles.

It does not mean that esomeprazole automatically starts working faster or gives better symptom relief for everyone. Both medicines reduce stomach acid through the same basic mechanism, and how quickly symptoms improve can vary between people and conditions.

It is also worth correcting another common misunderstanding. Omeprazole is not made from one "active" and one "inactive" form. It is a racemic mixture containing two stereoisomers. Esomeprazole contains the S isomer specifically.

Can You Switch from Omeprazole to Esomeprazole?

In many cases, switching between the two is straightforward because their standard doses are broadly equivalent.

For example, NICE considers omeprazole 20mg and esomeprazole 20mg equivalent for its standard PPI dosing framework.

However, do not assume that the same milligram dose is appropriate for every condition. Your prescriber may choose a different dose depending on whether you are being treated for GORD, severe oesophagitis, an ulcer or another condition.

If you are already taking a higher dose, have been using a PPI for a long time or take other medicines, check the switch with your prescriber or pharmacist first.

You also do not need to assume that esomeprazole will automatically work better. If your symptoms change after switching, tell your prescriber so they can decide whether the dose or treatment needs reviewing.

Clopidogrel: An Important Interaction to Know About

Both omeprazole and esomeprazole can interact with clopidogrel.

Omeprazole can reduce the formation of clopidogrel's active metabolite and may reduce its antiplatelet effect. UK product information therefore advises that concomitant use of omeprazole and clopidogrel should be discouraged.

Esomeprazole also inhibits CYP2C19, the enzyme involved in activating clopidogrel, so it is not a straightforward alternative when someone taking clopidogrel needs a PPI.

If you take clopidogrel, tell your prescriber or pharmacist before starting or switching PPIs. Another PPI may be considered instead, depending on your circumstances.

Do not stop clopidogrel or change your PPI on your own.

How Both Proton Pump Inhibitor Medicines Work

Both omeprazole and esomeprazole are PPIs. They reduce stomach acid by blocking the proton pumps involved in acid production in the stomach.

This can help control acid reflux symptoms and allow acid related damage to the oesophagus to heal. Both medicines are also used for other acid related conditions, including some stomach and duodenal ulcers.

Neither medicine is an instant antacid. Some people notice improvement within the first few days, but the time it takes to feel better varies. If symptoms continue despite treatment, speak to your prescriber rather than simply increasing the dose.

Do You Need to Take Either Before Food?

Not necessarily. Omeprazole can be taken with or without food according to NHS guidance.

Esomeprazole can also be taken with or without food. NHS guidance advises taking it once a day, usually first thing in the morning, unless you have been prescribed a different schedule. If you take it twice a day, the doses are usually taken in the morning and evening.

There is therefore no universal rule that everyone must take either medicine 30 to 60 minutes before food.

The important thing is to follow the instructions for your particular medicine and prescription. If your prescriber has given you specific timing instructions, follow those.

What Does the Evidence Say About Omeprazole and Esomeprazole?

The two medicines can both be effective treatments for acid related conditions. NICE considers esomeprazole 20mg equivalent to omeprazole 20mg in its standard PPI dose framework.

Some clinical studies have found differences between PPIs at particular doses or in specific groups of people. For example, NICE's evidence review includes studies comparing esomeprazole 40mg with omeprazole 20mg in severe erosive oesophagitis.

That does not mean esomeprazole is automatically the better choice for everyone with reflux. The appropriate medicine depends on the condition, dose, previous response, other medicines and individual circumstances.

For many people, cost and personal response are practical factors when choosing between the two.

Common Side Effects: Broadly Similar Between the Two

Both medicines can cause side effects such as headache, stomach pain, nausea, diarrhoea, constipation and wind. Not everyone experiences side effects, and they can vary from person to person.

Long term PPI treatment can also be associated with problems such as low magnesium and vitamin B12 deficiency in some people, as well as an increased risk of fractures. If you need long term treatment, your prescriber can review whether you still need the medicine and whether the dose remains appropriate.

Seek medical advice if you develop unusual or severe symptoms, particularly signs of an allergic reaction or another serious side effect.

Cost Difference

At EverydayMeds, generic omeprazole 20mg is listed from £12.99, compared with esomeprazole from £16.99.

These are provider prices and can change. Price is only one factor when choosing a PPI. The most suitable medicine also depends on your condition, other medicines and how you respond to treatment.

Some lower strength or over the counter products also have specific limits on how long they should be used without medical advice. For example, NHS guidance says that people buying esomeprazole without a prescription should not take it for longer than 14 days without speaking to a doctor.

Available Treatments for Acid Reflux

Medical Disclaimer

This page provides general information comparing omeprazole and esomeprazole doses. It is not a substitute for personalised medical advice.

Do not increase, reduce or switch your PPI dose without discussing it with your prescriber or pharmacist. The appropriate dose depends on the condition being treated, your response and any other medicines you take.

Tell your healthcare professional about all medicines, supplements and herbal remedies you use, particularly if you take clopidogrel.