When two or more medicines are taken at the same time, the effects of one of the medicines can alter the effects of the other. This is known as a drug-drug interaction. Clopidogrel can interact with other medicines.

Some of the more common interactions are listed below. However, this is not a complete list.

Increased risk of bleeding

There is an increased risk of bleeding when clopidogrel is taken with some other medications, including:

• aspirin
• non-steroidal anti-inflammatory painkillers (NSAIDs) – such as diclofenac, ibuprofen and naproxen
• dipyridamole – another type of antiplatelet
• warfarin – anticoagulant medicine that prevents your blood from clotting
• newer types of antiplatelet medicines – such as prasugrel, ticagrelo and cangrelor
• newer types of antithrombotic medicines – such as ticlopidine or GpIIb/IIIa inhibitors (abciximab, tirofiban, eptifibatide, ximelgatran and dabigatran)

Some medications may also prevent clopidrogrel from working as well as it should, or interact in other ways. For example, if you’re taking medication for stomach acid problems, your dose may need to be altered.

If you want to check your medicines are safe to take with clopidogrel, ask your doctor or pharmacist or read the patient information leaflet that comes with your medicine.

Interactions with food and alcohol

There are no known interactions between clopidogrel and food, although it is a good idea to take clopidogrel with or after food, to help reduce irritation to the stomach.

It may be safe to drink alcohol with clopidogrel as long as you:

• check the patient information leaflet that comes with the medicine
• take the correct dose of your medicine
• do not drink more than the maximum recommended daily limits of alcohol

Taking more than the recommended dose increases the risk of irritation to your stomach lining. This risk is increased further if you drink more than the recommended daily limits and may lead to bleeding from the stomach.

Clopidogrel (brand name Plavix) is an antiplatelet medicine. This means it reduces the risk of blood clots forming.

Normally, when there is a cut or break in a small blood vessel, a blood clot forms to plug the hole until the blood vessel heals.

Small cells in the blood called platelets cause the blood to clot. When a platelet detects a damaged area of a blood vessel, it produces a chemical that attracts other platelets and makes them stick together to form a blood clot.

Clopidogrel reduces the ability of the platelets to stick together and reduces the risk of clots forming. This protects you from having a stroke or heart attack.

When is clopidogrel used?

You may be given clopidogrel if you have had:

• a heart attack
• acute coronary syndrome (minor heart attack or unstable angina)
• a stroke or transient ischaemic attack (TIA)
• a coronary stent (a device to open up a blocked artery to the heart)
• an open heart operation
• peripheral arterial disease
• a vascular operation

Clopidogrel and low-dose aspirin

Sometimes, you may be given both low-dose aspirin and clopidogrel. Taken together, they are very effective, but there is a higher risk of bleeding, usually in the gut. This risk increases with age. The key question for your doctor is whether the benefits outweigh the extra risk.

This combination treatment is prescribed for a limited period of time, usually up to a maximum of 12 months. After this period, your specialist will usually advise you to stop one of the two antiplatelet medications.

Things to consider

If you have certain health conditions such as a peptic ulcer or bleeding disorder you should not take clopidogrel, unless advised by a specialist.

You should use clopidogrel with caution if you have liver or kidney problems.

Clopidogrel must not be given to anyone under 16 years old, unless under specialist advice. It’s also not recommended if you’re pregnant or breastfeeding.

Read more about things to consider before taking clopidogrel.

Side effects

Although serious reactions are rare, clopidogrel can cause side effects including indigestion and nausea.

Read more about the side effects of clopidogrel.

Clopidogrel can also interact with other medicines. Always read the patient information leaflet that comes with your medicine to check it is safe to take with clopidogrel. If you are unsure, ask your pharmacist or GP.

Read more about how clopidogrel interacts with other medication.

Missed or extra doses

If you forget to take your dose of clopidogrel, take that dose as soon as you remember, then continue to take your course of clopidogrel as normal.

However, if it’s almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

If you have to take two doses closer together than normal, there is an increased risk of side effects.

The patient information leaflet that comes with your medicine should also give you advice about what to do.

If you accidentally take an extra dose or doses of clopidogrel, contact your GP or call NHS 111 for advice.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: venous thromboembolism risk assessment and prophylaxis

Clopidogrel can cause side effects, although serious reactions are rare.

Common side effects of clopidogrel can include:

• headaches or dizziness
• nausea
• diarrhoea or constipation
• indigestion (dyspepsia)
• stomach ache or abdominal pain 
• nosebleeds 
• increased bleeding (your blood taking longer to clot – for example, when you cut yourself), or easy bruising

Speak to your GP if any of these side effects get worse or don’t go away.

Although clopidogrel is unlikely to affect your ability to drive, some people may feel dizzy when taking it. Avoid driving if you feel dizzy.

Serious side effects

More serious side effects can include:

• rashes and itching
• severe stomach ache or abdominal pain
• uncontrolled bleeding or unusual bruising
• vomiting with blood
• weakness or numbness in an arm or leg
• blood in your urine (haematuria) 
• blood in your stools

Speak to your GP or call NHS 111 immediately if you experience any of these side effects or any other unusual problems while taking clopidogrel.

Allergic reaction

In some cases clopidogrel can cause an allergic reaction. Go to the nearest hospital’s accident and emergency department (A&E) if you experience:

• swelling of the lips, mouth or throat
• breathing problems
• a skin rash that appears quickly

Clopidogrel may not be suitable to take if you have certain health conditions or are taking other medications.

When to avoid clopidogrel

Clopidogrel should not be taken if you have:

• an active (bleeding) peptic ulcer
• recently had a brain haemorrhage
• haemophilia or any other bleeding disorder

Clopidogrel must not be given to anyone under 16 years old, unless under specialist advice.

Read information about how clopidogrel interacts with other medications.

Using clopidogrel with caution

Clopidogrel should be taken with caution if you:

• have liver problems
• have kidney problems
• are at risk of bleeding, for example, if you are at risk of peptic ulcers

Tell your GP if you’ve had an allergic reaction to any medications before taking clopidogrel.

Some people are advised to stop taking clopidogrel seven days before a planned operation or dental extraction (removal of a tooth). This should always be on the advice of your doctor or surgeon.

Pregnancy and breastfeeding

Clopidogrel is not recommended if you’re pregnant or breastfeeding. This is because there’s very little information on its use in pregnant and breastfeeding women.