Anticoagulants are a blood-thinning medication used to reduce the risk of having a stroke, or when you have other conditions such as:

• Atrial fibrillation 
  An irregular heart rhythm
• Deep vein thrombosis (DVT) and pulmonary embolus (PE) 
  DVT is a blood clot in a vein, usually in the leg. PE is a blood clot which breaks off into the blood stream and blocks one of the blood vessels in the lungs
• Mechanical heart valves
  Hearts fitted with a mechanical valve need long-term anticoagulation treatment to prevent blood clots forming on the valve

Although warfarin is the most widely-used anticoagulant, there are others, including the new or novel oral anticoagulants (NOACs):

• Dabigatran
• Rivaroxaban
• Apixaban
• Edoxaban

Warfarin

Warfarin is an anticoagulant (or blood-thinning medication) to reduce the risk of having a stroke.

When taking warfarin you need to be aware of certain things that can alter your warfarin levels including alcohol, some foods and medicines. Click on the information tab above to find out more.

How warfarin works

Warfarin works by increasing the time that it takes for your blood to clot and will reduce the risk of a thrombus forming within the heart. Warfarin works by blocking vitamin K, which is involved in the clotting process.

When you start taking warfarin, its effects will have to be monitored long term by blood tests. You will be referred to an anticoagulation clinic or your GP will monitor your treatment. You will also be given a yellow "Oral Anticoagulation Therapy" booklet with more information about warfarin. 

Warfarin effects are measured by your INR (international normalised ratio) levels. The INR level shows how quickly your blood is clotting. More often, the INR levels should be maintained between 2 and 3. If your levels are below 2 then you are not fully protected from a stroke and if your levels are too high (above 3), then you are at a higher risk of bleeding. There are some exception to this rule so please speak with your doctor or nurse to see what INR is considered therapeutic for you.

You should make sure that you take your dose of warfarin once a day, at the same time each day; usually, in the evening is best. When taking warfarin you need to be aware of certain things that can alter your warfarin levels including alcohol, some foods, other side effects, and operations and dental surgery. Click on the 'Information tab' to find out more.

Warfarin side effects

When you are on warfarin you are likely to bruise easily and it will take longer for a simple cut to stop bleeding.   

The most serious side effect of anticoagulants is excessive bleeding. If you experience any of the following, you must seek medical attention and have an urgent INR test: 

• unexplained severe bruising
• prolonged bleeding from small cuts, or nose bleeds (more than 10 minutes)
• blood in vomit
• blood in sputum
• passing blood in your urine or faeces
• passing black faeces
• severe or spontaneous bruising
• unusual headaches
• for women, heavy or increased bleeding during your period or any other vaginal bleeding

You should seek immediate medical attention if you: 

• are involved in a major trauma
• suffer a significant blow to the head
• are unable to stop the bleeding

Further information

It is important to be aware of certain things that can alter your warfarin levels including alcohol, some foods and medicines. Click on the information tab to find out more.

Direct oral anticoagulant medications (DOACs)

Direct oral anticoagulants (or DOACs) are now available as an alternative treatment to warfarin.  

DOACs include dabigatran, rivaroxaban, apixaban and edoxaban.

They have been approved by NICE (National Institute for Heath and Care Excellence) for the prevention of strokes in patients with AF.

These drugs work in a similar way to warfarin by increasing the time it takes for your blood to clot and have been shown in clinical trials to be at least as effective as warfarin. 

The main advantage of DOACs compared to warfarin is that they do not need monitoring, so you will not need to go for regular blood tests. They are also less affected by different foods and, providing you take the tablet as instructed, the levels will remain stable. 

Side effects

The side effects of these medications are similar to warfarin. When you are on a DOAC, you are likely to bruise easily, and it will take longer for a simple cut to stop bleeding. The most serious side effect of DOACs is prolonged or heavy bleeding, although the risk of serious bleeding is less than warfarin.   

You should contact your doctor immediately if you experience any of the following: 

• prolonged nose bleeds (more than 10 minutes)
• blood in vomit
• blood in sputum
• passing blood in your urine or faeces
• passing black faeces
• severe or spontaneous bruising
• unusual headaches
• for women, heavy or increased bleeding during your period or any other vaginal bleeding.

You should seek immediate medical attention if you:

• are involved in major trauma
• suffer a significant blow to the head
• are unable to stop the bleeding.

Not all atrial fibrillation (AF) patients will be a suitable to receive these new medications. If you have a metal (or mechanical) heart valve you will not be suitable for a NOAC and will be prescribed warfarin instead. 

Dabigatran

Dabigatran is available in two different strengths (either 150mg or 110mg capsules) and should be taken twice a day with meals.  

The 150mg dose is the only NOAC that has been shown to be better than warfarin at preventing strokes in patients with AF. The 110mg dose has been shown to be equivalent. 

Depending on your age, weight, kidney function, other medical conditions you have and the tablets you are taking, your doctor or healthcare professional will decide with you which dose is the most appropriate.

Dabigatran side effects

The most common side effect people experience with dabigatran, other than bleeding and bruising easily, is indigestion or heartburn. These gastrointestinal side effects occur in around 10 per cent of patients. This can be minimised by taking your capsules with food and making sure that you swallow them whole.   

If you experience indigestion, speak to your doctor as they may want to give you a medication to reduce the acid in the stomach. These medications are sometimes known as PPIs (proton pump inhibitors) and include omeprazole, lansoprazole and pantoprazole.   

It is important that if you vomit blood, see blood in your urine (making it red or brown) or have blood in your stools (making it look red or black), you contact your doctor immediately.

Rivaroxaban

Rivaroxaban is available in two different strengths (20mg and 15mg tablets) and should be taken once a day.  It is best to take the medication with your biggest meal of the day, at the same time each day. We will normally recommend that you take it with your evening meal. This helps to ensure that the medication is absorbed properly into the bloodstream.

Rivaroxaban has been shown to be equivalent to warfarin in preventing strokes in patients with AF. 

Depending on your kidney function and other medical conditions, your doctor or healthcare professional will decide with you which dose is the most appropriate. Rivaroxaban is sometimes tolerated better than dabigatran. However, the same bleeding risks still apply with this medicine.  

Apixaban

Apixaban is available in two different strengths (5mg and 2.5mg tablets) and should be taken twice a day.  

Depending on your age, kidney function and body weight, your doctor or healthcare professional will decide with you which dose is the most appropriate.

If you have had a bleed or ulcer in your stomach, your doctor may prefer you to be prescribed apixaban rather than warfarin or one of the other NOACs. This is because apixaban is the only NOAC that has been shown to have lower rates of gastrointestinal (or stomach) bleeding in comparison to warfarin.