What are direct oral anticoagulants (DOACs) and how do they work?

Jump straight to:

• What is an anticoagulant medicine?
• What are direct oral anticoagulants (DOACs) and who are they recommended for?
• Types of DOACs
• How do they work?
• Does this mean everyone who is taking warfarin should swap to a DOAC?
• What are the side effects of DOACs?
• What happens if you forget to take a dose?
• Are there people for whom DOACs are unsuitable?

What is an anticoagulant medicine?

An anticoagulant medicine makes the blood take longer to clot. It plays a vital part in helping to prevent strokes specifically caused by atrial fibrillation (AF), which is the most common abnormal heart rhythm in the UK. 

AF increases the risk of stroke as it can lead to blood pooling in the heart, which increases the risk of clots forming. If these clots are ejected by the heart, they can block a blood vessel in the brain and cause a stroke.

Warfarin is the most commonly prescribed anticoagulant and is a very effective way of reducing the risk of AF-related strokes. But it requires frequent blood tests and careful monitoring.

What are direct oral anticoagulants (DOACs) and who are they recommended for?

Direct oral anticoagulants (DOACs) are a type of anticoagulant drug. Like warfarin, DOACs help to prevent blood clots from forming.

They are used in the prevention of stroke for people with non-valvular AF, which is when AF is not associated with a heart valve problem. Non-valvular AF is the type of AF that most people in the UK have.

DOACs can also be used in the management of venous thromboembolism, which is when a blood clot forms in a vein. 

Types of DOACs

There are different types of DOACs including: 

• rivaroxaban (brand names include Xarelto) 
• dabigatran (brand names include Pradaxa) 
• apixaban (brand names include Eliquis) 
• edoxaban (brand names include Lixiana).  

How do DOACs work?

DOACs interrupt part of the complex system involved in the formation of blood clots. This causes the blood to take longer to clot and reduces the risk of AF-related stroke.

DOACs have been shown to be as effective at preventing strokes as warfarin. The main difference between DOACs and warfarin is that DOACs are less influenced by diet and other medications.

A set dose of a DOAC can be prescribed and the doctor will know that you are protected against stroke as long as the drug is taken. This means that you don’t need to have blood tests to check whether it is working. 

It’s important to follow the instructions your doctor has given you on how and when to take your DOAC. Your dose will depend on which type of DOAC you are prescribed. Take your medicine at the same time every day. You should take some types of DOACs after food, but other DOACs can be taken with or without food. Check with your pharmacist if you have any questions about this. 

Does this mean everyone who is taking warfarin should swap to a DOAC?

No, warfarin is very effective at preventing strokes, and if you’re well controlled on warfarin and are not having any side effects, there is no need to swap to a DOAC. 

However, in some cases, it may be appropriate to switch from warfarin to a DOAC. But this will be done with careful consideration and discussion with your doctor. 

What are the potential side effects?

As with all medications, DOACs can cause side effects for some people. Different DOACs can cause different side effects, so read the patient information leaflet that comes with your medicine.  

With all anticoagulants, bleeding is a possible side effect. A serious complication that can happen is having a major bleed. It’s uncommon, and the chance of having a major bleed with a DOAC is either the same or less than it is if you are taking warfarin.  

The treatment for a bleed will depend on where you are bleeding from and the extent of it. Some signs and symptoms can include: 

• unexpected bleeding, such as vomiting blood 
• bleeding that lasts a long time, for example, a nose bleed 
• severe or unexplained bruising, or bruising that gets bigger  
• red or black (tar-like) poo. 

Contact your doctor if you have any signs or symptoms of unusual bleeding. If there are signs of internal bleeding or the bleeding is severe, call 999. There are drugs available which can reverse the effects of apixaban, dabigatran and rivaroxaban. Also, the anticoagulation effect of DOACs fades quickly, around 12–24 hours after the last dose.  

If you are taking any type of anticoagulant medicine and you suffer a head injury, such as falling and hitting your head, or if you experience a blow to the head, seek immediate medical help so you can be checked for internal bleeding which may not be immediately obvious. 

What happens if you forget to take a dose?

It’s essential that DOACs are taken every day. The anticoagulant effect of DOACs fades 12-24 hours after the last dose so if you miss a dose, you’re not protected. If you’ve forgotten a dose and it is less than half the time to the next scheduled dose of the drug, take the medicine and continue as normal. If not, take the next dose at the scheduled time. It is important not to take a double dose of the medicine, as that could increase the risk of bleeding. 

Are there any other precautions I need to take?

Some medications don’t mix well with DOACs. They can affect how they work and can increase the chance of side effects. Always speak to your doctor or pharmacist before taking any other medicine. Don’t take aspirin and ibuprofen, unless your doctor says it’s OK, as they can increase the risk of bleeding. For a full list of medicines that you should avoid, check the patient information leaflet that comes with your medicine. 

Also talk to your doctor or pharmacist before taking any herbal remedies, vitamins or supplements. Don’t take St John's wort while you're taking a DOAC as it can increase your risk of side effects. 

Always tell any healthcare professional looking after you that you take a DOAC. If you need to have surgery or an invasive procedure, you may be advised to stop taking your DOAC beforehand. If you're having a dental procedure, such as having a tooth removed, tell your dentist that you take anticoagulants.  

Only stop taking your DOAC if your doctor advises you to. It’s also a good idea to have an anticoagulation alert card on you at all times.   

Taking DOACs can make you more prone to bleeding if you're injured. Try to avoid minor injuries and cuts and grazes. Take care and when shaving and use protection when gardening or playing sports. You may be advised to avoid contact sports because of the risk of bleeding. 

Are there people for whom DOACs are unsuitable?

If a person has a high risk of bleeding, then anticoagulants including DOACs and warfarin, may not be recommended. DOACs are not recommended for people who have a mechanical heart valve. If you have kidney damage, DOACs may not be recommended, as it can increase the risk of bleeding for some people. 

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