Search any omeprazole interaction checker and you may see a long list of medicines. That can be technically correct but not very helpful. In practice, omeprazole drug interactions matter for different reasons. Omeprazole reduces stomach acid, which can affect the absorption of some medicines, and it also inhibits the liver enzyme CYP2C19, which can affect how some medicines are broken down.
Some combinations need particular attention, including clopidogrel, certain anticoagulants, some antifungal medicines, methotrexate and some HIV medicines. Others can usually be used together with appropriate monitoring. The importance of an interaction also depends on the medicine involved, the dose, how long you take it and your individual health.
This guide explains which omeprazole interactions are more important, which combinations are usually manageable and which are less likely to cause a problem. It also covers the medicine combinations people often ask about, including clopidogrel, warfarin, iron supplements, apixaban, propranolol and prochlorperazine. You will also find information about dose timing, interaction checkers and some of the possible effects of longer term PPI treatment.
The important point is that an interaction does not always mean that two medicines cannot be used together. Some combinations simply need a different medicine, closer monitoring or advice about when to take them.
Key Things to Know When Taking Omeprazole
- Omeprazole can interact with medicines in different ways. It can change stomach acidity and can also affect enzymes involved in medicine metabolism
- Clopidogrel is one of the most important combinations to know about. UK guidance recommends avoiding omeprazole and esomeprazole with clopidogrel and using another PPI where appropriate
- Changing the time you take two medicines can sometimes help with an absorption interaction, but it does not reliably prevent an enzyme interaction
- There is no established clinically significant interaction between omeprazole and propranolol
- No specific interaction between omeprazole and prochlorperazine is listed in the current UK omeprazole product information, although each medicine has its own side effects and precautions
- Apixaban does not have the same type of interaction with omeprazole as clopidogrel does. A PPI may sometimes be prescribed alongside an anticoagulant when the clinician considers protection against upper gastrointestinal bleeding appropriate
- Always tell your prescriber or pharmacist about everything you take, including vitamins, supplements, herbal products and medicines bought without a prescription
How Omeprazole Drug Interactions Occur With Other Medications
Omeprazole interactions can happen in several ways. Understanding the mechanism can help explain why changing the time of a dose sometimes helps, while in other cases it does not.
Mechanism One: Raised Stomach pH
Omeprazole reduces the amount of acid in the stomach. Some medicines need an acidic environment to dissolve or be absorbed properly, so reducing stomach acid can lower their absorption.
Other medicines may be absorbed slightly more when stomach acid is reduced. The effect depends on the individual medicine, so it is not correct to assume that omeprazole always reduces absorption.
Mechanism Two: CYP2C19 Inhibition
Omeprazole is mainly broken down by CYP2C19 and also inhibits this enzyme. As a result, medicines that rely on CYP2C19 for their metabolism can sometimes reach higher levels in the body.
Clopidogrel is different. It is a prodrug that needs CYP2C19 to form its active metabolite. Omeprazole can reduce this activation, which is why the combination is discouraged.
This distinction matters when deciding whether changing the time of the doses will help. An absorption interaction may sometimes be managed by changing when medicines are taken. An interaction caused by enzyme inhibition is not usually solved by simply taking the medicines several hours apart.
The Omeprazole Interactions That Matter Most
The list below covers some of the more important interactions in the UK product information. It is not a complete list, and the appropriate action depends on the medicine and the person's circumstances.
| Medicine | What happens | How it is usually handled |
|---|---|---|
| Clopidogrel | Omeprazole can reduce formation of clopidogrel's active metabolite | Avoid the combination where possible. If acid suppression is needed, another PPI such as lansoprazole, pantoprazole or rabeprazole may be considered |
| Warfarin | Omeprazole can affect warfarin metabolism and may alter anticoagulant control | Monitoring of INR may be needed when treatment is started, stopped or changed |
| Rilpivirine | Absorption can be substantially reduced by increased stomach pH | Proton pump inhibitors are contraindicated with rilpivirine |
| Atazanavir | Absorption can be reduced | The combination with a PPI is generally not recommended and requires specialist consideration if unavoidable |
| Nelfinavir | Omeprazole can reduce nelfinavir exposure | The combination should be avoided |
| Ketoconazole and itraconazole | Absorption can be reduced when stomach acid is suppressed | A prescriber may need to consider an alternative or other treatment approach |
| Erlotinib | Absorption can be reduced | Concomitant use with omeprazole should be avoided |
| Methotrexate, particularly at high doses | PPI use has been associated with increased methotrexate levels in some patients | With high dose methotrexate, temporary withdrawal of the PPI may be considered by the treating team |
| Digoxin | Omeprazole can slightly increase digoxin exposure | Monitoring may be appropriate in people at higher risk, particularly with higher PPI doses |
| Tacrolimus | Omeprazole can increase tacrolimus levels | Tacrolimus levels and kidney function may need closer monitoring |
| Diazepam and phenytoin | Omeprazole can reduce their metabolism and increase exposure | The prescriber may consider monitoring or a dose adjustment |
| Citalopram and escitalopram | Omeprazole can increase exposure to these medicines | Dose limits and individual risk factors should be considered by the prescriber |
| St John's Wort and rifampicin | They can increase the breakdown of omeprazole and reduce its levels | Tell your prescriber or pharmacist if you take either of these |
These examples come from UK product information, which also notes that the clinical importance varies between medicines and circumstances.
Clopidogrel, the One Worth Knowing By Name
If you take clopidogrel, make sure your prescriber or pharmacist knows if you also take omeprazole.
Omeprazole and esomeprazole can interfere with the activation of clopidogrel. Current NHS Specialist Pharmacy Service guidance recommends avoiding these two PPIs with clopidogrel and using another PPI, such as lansoprazole, pantoprazole or rabeprazole, when acid suppression is needed.
Do not stop clopidogrel or change your PPI yourself. If you are already taking both, speak to the prescriber who manages your medicines. The timing of the two medicines does not reliably solve this interaction because it is related to CYP2C19 inhibition rather than simply the medicines being in the stomach at the same time.
A Correction Worth Making About Digoxin
Digoxin is sometimes listed in interaction checkers because omeprazole can affect its exposure. The effect is in the direction of increased, rather than reduced, digoxin exposure.
UK product information reports that omeprazole 20mg daily increased digoxin bioavailability by about 10% in healthy volunteers. Digoxin toxicity has been reported rarely. The risk is more relevant in people who are older, taking higher doses of omeprazole or otherwise at risk of digoxin toxicity. Monitoring may be appropriate in these situations.
Omeprazole and Iron Tablets Together
This is a common question, and the answer is more nuanced than simply saying that the two medicines cannot be taken together.
Omeprazole reduces stomach acid, and stomach acid helps with the absorption of some forms of oral iron. The UK omeprazole product information lists iron salts among medicines whose absorption may be reduced by acid suppression.
However, this does not mean that everyone taking omeprazole will become iron deficient or that iron treatment will stop working. The practical importance depends on factors such as how long you have been taking omeprazole, your existing iron levels, the type of iron preparation and why you need iron treatment.
If you are taking iron for confirmed iron deficiency and your blood results are not improving as expected, tell your prescriber that you also take omeprazole. They can decide whether the treatment or the way you take it needs to change.
Practical Points on the Omeprazole Iron Tablet Interaction
- Tell the person managing your iron treatment that you take omeprazole
- Taking the two medicines at exactly the same time is not generally considered dangerous, but your pharmacist or prescriber may advise different timing if absorption is a concern
- Vitamin C can improve the absorption of some oral iron preparations, although whether you need extra vitamin C depends on your diet and treatment
- Different iron preparations do not all behave in exactly the same way, so do not change your iron product without checking first
- If you are taking long term acid suppression and being treated for iron deficiency, your healthcare professional can monitor your blood results and decide whether further investigation is needed
Do I Need to Take Omeprazole With Apixaban?
Omeprazole and apixaban do not have the same important interaction as omeprazole and clopidogrel.
Apixaban is affected mainly by medicines that strongly inhibit or induce CYP3A4 and P glycoprotein. Omeprazole is not listed among the strong inhibitors that require the specific apixaban restrictions described in the UK product information.
A proton pump inhibitor may sometimes be prescribed alongside an anticoagulant such as apixaban when a person has a higher risk of upper gastrointestinal bleeding. This can be particularly relevant when other medicines that increase bleeding risk are also being used or there is a history of gastrointestinal ulceration or bleeding.
However, not everyone taking apixaban needs a PPI. The decision depends on your individual bleeding and gastrointestinal risk.
Dabigatran is different. Its absorption can be affected by changes in stomach acidity, so it should not be treated as though it has the same interaction profile as apixaban.
Omeprazole and Propranolol Together
There is no established clinically significant interaction between omeprazole and propranolol that normally requires the two medicines to be separated.
That does not mean that every person can take both without any other considerations. Propranolol has its own precautions and interactions, and the reason you have been prescribed it also matters.
If you have been prescribed both medicines, take them according to the instructions you have been given. If you notice new dizziness, fainting, breathing problems or other worrying symptoms, speak to a healthcare professional rather than assuming that omeprazole is responsible.
Prochlorperazine and Omeprazole
There is no specific clinically significant interaction between omeprazole and prochlorperazine listed in the UK omeprazole product information.
The two medicines can sometimes be used in the same person for different reasons. Prochlorperazine is used for problems such as nausea, vomiting and vertigo, while omeprazole is used to reduce stomach acid.
The main precautions relate to prochlorperazine itself. It can cause drowsiness and movement related side effects, and alcohol can make some of these effects worse.
If you have been prescribed both medicines, take them as directed. If you develop severe drowsiness, unusual movements, significant dizziness or other concerning symptoms, speak to your doctor or pharmacist.
Nutrients and Long Term Use
These are not classic drug interactions, but they are worth knowing about if you take omeprazole for a long time.
- Vitamin B12 absorption can be reduced because stomach acid helps release vitamin B12 from food. The risk is more relevant in people who already have low B12 levels or other risk factors
- Low magnesium has been reported with PPI treatment, particularly with prolonged use. The UK product information says the risk can be more relevant when PPIs are used with medicines such as digoxin or diuretics
- Calcium and bone health have been studied in people taking PPIs long term. Some studies have found an association with fractures, particularly with higher doses and longer treatment, although this does not mean that everyone taking omeprazole will develop a bone problem
- PPI treatment may slightly increase the risk of gastrointestinal infections, including C. difficile infection in some settings
- Rare skin reactions, including subacute cutaneous lupus erythematosus, have been reported with PPIs. Speak to a healthcare professional if you develop an unusual rash, particularly after sun exposure
These potential risks are not a reason to stop treatment on your own. If you have been taking omeprazole for a long time, your prescriber can review whether you still need it and whether any monitoring is appropriate.
Does Spacing Doses Apart Help?
Sometimes, but it depends on the type of interaction.
| Type of interaction | Does spacing help? | Why |
|---|---|---|
| Absorption affected by stomach acidity | Sometimes | Changing when medicines are taken can sometimes reduce an absorption problem, depending on the medicine |
| Metabolic interaction caused by CYP2C19 inhibition | Usually no | The enzyme effect is not simply caused by both medicines being present in the stomach at the same time |
This is why separating omeprazole and clopidogrel is not a reliable solution. The interaction is related to CYP2C19 and can occur even when the medicines are taken at different times. UK guidance recommends using another PPI rather than trying to solve the interaction by spacing the doses.
Iron is different. If there is a concern about absorption, your pharmacist or prescriber may suggest a particular schedule based on the iron preparation you are using.
Antacids are another separate case. They work differently from omeprazole and can sometimes be used alongside it. Follow the instructions on the specific antacid and ask a pharmacist if you are unsure about timing with your other medicines.
Using an Omeprazole Interaction Checker Sensibly
Online interaction checkers can be useful, but a long list of results does not necessarily mean that you have a long list of serious problems.
Keep these points in mind:
- An interaction checker may list theoretical or minor interactions alongside combinations that genuinely require a treatment change
- It does not know your complete medical history, kidney or liver function, treatment duration or the reason you take each medicine
- It cannot decide whether the benefit of using two medicines together outweighs the possible interaction
- Some combinations are deliberately prescribed together when the potential benefit is considered greater than the risk
- The same interaction can have different importance depending on the dose and the person taking the medicines
Use an interaction checker as a starting point for questions rather than as a reason to stop a medicine. If you are concerned about a result, show the list to your pharmacist, GP or prescriber so they can assess the interaction in context.
What to Tell Your Prescriber
A medication review works best when your healthcare professional has the complete picture. Tell them about:
- All prescribed medicines, including medicines prescribed by another GP, hospital or online service
- Medicines bought without a prescription, including painkillers and indigestion remedies
- Vitamins, minerals and herbal products
- Medicines you have recently stopped, because some interactions can continue after a medicine is discontinued
- Any previous stomach ulcer or gastrointestinal bleeding
- Any new symptoms such as unusual bruising, bleeding, severe diarrhoea or persistent abdominal problems
If another healthcare professional starts a new medicine, mention that you take omeprazole. This gives them a chance to check for interactions before you begin the new treatment.
Treatment Options and Prices
If an interaction means that omeprazole is not the most suitable option, another proton pump inhibitor or an H2 blocker may sometimes be considered. Which treatment is appropriate depends on your symptoms, other medicines and individual medical history.
You can begin an online assessment for acid reflux to have your treatment reviewed by a UK registered prescriber.
| Treatment | From |
|---|---|
| Omeprazole 20mg | £12.99 |
| Losec MUPS 20mg tablets | £29.99 |
| Lansoprazole 15mg capsules | £5.99 |
| Lansoprazole 15mg orodispersible tablets | £8.49 |
| Pantoprazole | £5.99 |
| Rabeprazole | £19.99 |
| Esomeprazole | £16.99 |
| Famotidine tablets | £8.49 |
Prices are correct at the time of writing and the live pricing on the site takes precedence. Further information is available in the omeprazole prescription guide and the omeprazole 20mg dosage guide.
Medical Disclaimer
This article is for general information and does not replace personalised medical advice. It is not a complete list of omeprazole drug interactions and should not be used to decide whether to start, change, space or stop any medicine.
Omeprazole is available as a Prescription Only Medicine in the UK for many uses and strengths, although some lower strength products are available without a prescription for short term use. Treatment suitability depends on the reason for treatment and an individual clinical assessment.
Do not stop or change a prescribed medicine without advice, particularly medicines such as anticoagulants or antiplatelet medicines. If you develop unusual bleeding, black tarry stools or vomit that contains blood or looks like coffee grounds, seek urgent medical advice.
Omeprazole can sometimes mask symptoms of other conditions. If symptoms persist, change or become worse despite treatment, speak to a healthcare professional.
Suspected side effects can be reported through the MHRA Yellow Card scheme.
