Blood-thinning medication and stroke

There are several types of blood-thinning medication that work in different ways. Despite the name, they don’t make your blood thinner. But they do reduce the risk of clots forming in your blood. 

Why are they used?

If you have a stroke due to a clot in the brain (known as an ischaemic stroke) or a transient ischaemic attack (TIA), you will probably need to start taking blood-thinning medication. This is a long-term treatment to reduce your risk of having another stroke. 

People with heart conditions such as atrial fibrillation (irregular heartbeat), may be given blood-thinning medications to reduce their risk of a stroke. 

If you have any questions or need support with your treatment, talk to your GP, pharmacist or specialist stroke nurse. 

What is a clot-busting medication? 

Clot-busting medication (alteplase) is a one-off emergency stroke treatment given in hospital. It breaks down clots to allow the blood to reach the brain cells and reduce damage in the brain. To learn more visit our resource page on ischaemic stroke. 

Benefits

Taking blood-thinning medication is often one of the main ways you can reduce your risk of a stroke if you have had a stroke or TIA, or have a heart condition. By reducing the risk of clots forming, they give you a much greater chance of recovering and staying healthy after a stroke.

Risks

Blood-thinning medications carry an increased risk of bleeding. This can be mild, such as small cuts or injuries taking slightly longer than usual to heal. There is also a small chance of more serious bleeding, such as bleeding in or around the brain (haemorrhagic stroke).

What’s right for you?

You will only be offered medication if the benefits to your health outweigh the risks. You are carefully assessed to work out which treatment is right for you. This depends on:

• The type of stroke you had.
• What caused the stroke.
• Other health conditions you have.
• Other medications you’re on.
• Your age.

Doctors discuss your options with you, and make sure you know how to take the medications. You’ll be monitored when you start taking medication. Your dose or the type of medication may be changed, and you might be given a combination of medications. 

Some other medications can affect the way blood-thinning medications work. This can put you at greater risk of a stroke or excessive bleeding.

These include some types of:

• Antibiotic.
• Antidepressant.
• Steroid.
• Epilepsy drugs.
• Non-steroidal anti-inflammatory (NSAID) such as ibuprofen.
• Some supplements and herbal medicines, such as St John’s Wort and Chinese medicine. 

If you are taking any other prescription medications or over-the-counter medicines or supplements, let your doctor or pharmacist know. 

Heavy periods and vaginal bleeding

Some women find that blood-thinning medication can give them heavy periods or vaginal bleeding between periods. Trans men who have periods might also have vaginal bleeding or heavy periods.

A heavy period could mean bleeding more heavily or for much longer than usual. You might need to change a pad or tampon every hour or two, leak blood, or pass blood clots.

How can heavy periods be managed?

Heavy periods can lead to low iron levels in your blood (anaemia). This needs to be treated with medication and sometimes blood transfusions. If your bleeding suddenly becomes much heavier, get medical help as soon as possible. 

Your GP or pharmacist can discuss options for reducing bleeding with you. Some women find that using an intrauterine system (IUD or contraceptive coil) reduces the bleeding. 

After the first few months of taking the blood-thinning medication, you might be able to go onto a slightly lower dose, as long as the doctor thinks your risk of a clot or stroke is under control. Don’t stop taking blood-thinning medication or reduce your dose without speaking to your GP, or you may be at risk of a stroke.

Pregnancy

You can’t take most types of anticoagulants while you’re pregnant or breastfeeding. So if you are pregnant or planning to have a baby, speak to your GP or midwife. You'll need help to manage your risk of a stroke or blood clots while pregnant. This may include having an injectable anticoagulant such as heparin.  

Antiplatelet medication is often the first blood-thinner used after a TIA or ischaemic stroke. This could include aspirin, clopidogrel and sometimes dipyridamole. Later, you might change to anticoagulants or stay on antiplatelets. Some people will start on anticoagulants straight away. 

You should have a checkup at least once a year to make sure the medication is working and check your other stroke risk factors. You will need more frequent checks if you are on some types of anticoagulant. 

This guide can only give general information. You should always get individual advice about your own health and any treatment you may need from a medical professional such as a GP or pharmacist. 

You can find more details about the medications in this guide on nhs.uk medicines. Always read the patient information leaflet that comes with your medication. 

There are several types of anticoagulant. Your doctor will discuss your options with you, including the risks and benefits of any medication. You should then decide together which anticoagulant would be the most suitable for you. 

Who can and can’t take anticoagulants

Most anticoagulants aren’t suitable while you are pregnant or breastfeeding (see ‘Heavy periods and pregnancy’ above). If you had a haemorrhagic stroke (due to bleeding in or around the brain) you’ll be assessed to help decide if and when you should take anticoagulants.

You might not be able to take some types of anticoagulant if you have:

• Liver or kidney problems.
• Thyroid problems.
• Blood-clotting disorders.
• Stomach ulcer. 

Monitoring and check-ups while you’re on anticoagulants

Direct oral anticoagulants (DOAC).

The most common type of anticoagulants are direct oral anticoagulants (DOAC). There are several types of DOAC including apixaban, dabigatran, edoxaban and rivaroxaban. 

Before starting on a DOAC, you will have blood tests to check for problems such as liver, kidney and blood clotting disorders. Once you are taking them you will have a follow-up check at one month. After that checks could be around three to six months apart depending on your age and health. The check-up looks at side effects including bleeding, and any help you need with taking your medication. You should have an annual kidney and liver function blood test.

Warfarin

Warfarin is an older type of medication which needs more monitoring than DOACs, but is still the best treatment for certain conditions. For full details of how warfarin is prescribed and monitored, see the ‘Warfarin’ section later in this guide. 

Quick guide to the different types of blood-thinning mediation

Apixaban (Eliquis)

Apixaban makes the blood less likely to clot by blocking a protein (Factor Xa) in the blood. You will not need to have regular blood tests.

How to take it

Try to take apixaban at a regular time of day. It’s usually taken twice a day, with or without food. 

Possible side effects

As well as the common problems mentioned in the ‘Side effects and what to look out for’ section above, other side effects of apixaban may include:

• Anaemia.
• Feeling dizzy or lightheaded.
• A mild rash. 

Dabigatran etexilate (Pradaxa) 

How it works

Dabigatran etexilate attaches itself to a protein (called thrombin) in your blood, making your blood less likely to form a clot. You should take dabigatran exactly as your doctor prescribes.

How to take it

Try to take dabigatran at a regular time of day. It’s usually taken twice a day, with or without food. 

Possible side effects

As well as the common problems mentioned in the ‘Side effects and what to look out for’ section above, other side effects of dabigatran may include:

• Stomach pain. 

Edoxaban (Lixiana)

How it works

Edoxaban, like apixaban and rivaroxaban, makes the blood less likely to clot by blocking a blood protein called factor Xa. You will not need to have regular blood tests. 

How to take it

Try to take edoxaban at a regular time of day. It’s usually taken once a day, either with or without food. 

Possible side effects

As well as the common problems mentioned in the ‘Side effects and what to look out for’ section above, other side effects of Edoxaban may include:

• Itchiness.
• Nausea. 

Rivaroxaban (Xarelto) 

How it works

Rivaroxaban makes the blood less likely to clot by blocking a protein (Factor Xa) in the blood. This protein plays a key role in the blood clotting process. 

How to take it

Try to take rivaroxaban at a regular time of day. It’s usually taken once or twice a day, and it’s best to take it just after a meal or a snack to help you absorb the dose. 

Possible side effects

As well as the common problems mentioned in the ‘Side effects and what to look out for’ section above, other side effects of Rivaroxaban may include:

• Dizziness.
• Mild rash.

Warfarin 

How it works

Warfarin blocks vitamin K, which is a substance that helps to create the protein fibres that make up blood clots. Reducing these proteins slows down clot formation.

How to take it 

Try to take warfarin at a regular time of day. It’s often taken in the evening. It’s usually taken once a day, either with or without food. 

Before starting warfarin, you will have tests to check for problems such as liver, kidney, blood clotting and thyroid disorders.

While you are taking warfarin, you have regular blood tests which measure how long your blood takes to clot. This is called the international normalised ratio (INR). At the start, you have daily tests, and your dose is adjusted until the target INR is achieved. Tests go down to twice weekly until your INR is stable. After that tests can be around 12 weeks apart but some people need more frequent checks. 

You might be able to use a self-testing kit at home. Speak to your GP to find out if this is possible for you. 

Food and drink on warfarin

Warfarin can be affected by what you eat and drink.

Food

Vitamin K can interfere with warfarin. Foods that are very high in vitamin K include:

• Green leafy vegetables such as spring greens, broccoli, spinach and lettuce.
• Chickpeas and avocado.
• Egg yolks, cheese and liver.
• Olive oil.

It’s important to keep a variety of healthy foods in your diet, including foods rich in vitamin K. But you should try to keep the amounts you eat fairly steady over time. If your diet changes, speak to your GP or pharmacist.

Drink

• Cranberry juice, grapefruit juice and pomegranate juice can increase the effect of warfarin, making bleeding more likely.
• Alcohol in large amounts can increase the effect of warfarin, so stay within the guidelines for safe limits of no more than 14 units of alcohol per week, spread over the week. 

Possible side effects 

The main side effect of warfarin is bleeding. Less common side effects of warfarin may include:

• Rashes.