What they do

Anticoagulants (also known as antithrombotics) prevent the formation or growth of blood clots. They are important because people with heart failure often produce blood clots in the heart or blood vessels.

Although anticoagulants are often referred to as blood thinners, they don't actually allow your blood to flow more freely through your vessels. Think of them as preventing blood from stopping (and clotting) where it shouldn't.

Warfarin is the most common anticoagulant and is taken as a tablet. The dose of warfarin varies between people. Your doctor or nurse will measure your INR frequently, especially during the beginning of your treatment, to determine the correct dose for you. It is important that you don't miss any tablets or take extra doses. If you do, you need to let your clinic know.

Sometimes you may be given an anticoagulant injection (usually a type of heparin) instead of warfarin, perhaps if you are in hospital for a medical procedure or if you are having trouble swallowing.

Side effects

Anticoagulants can increase the tendency to bleed, which usually shows as bruises. However, the risk of major haemorrhage (severe bleeding) is also increased, although the risk is low.

Top tips

You should tell all your doctors, including your primary care physician (GP), your dentist and community pharmacist that you are on warfarin. It is useful to carry a medical alert card or bracelet with you that lets people know you are on warfarin in case of emergencies.

Because of the risk of haemorrhage, it is important that you notify your doctor immediately if you notice any signs of bleeding, including unexplained bruising or bleeding from the gums, nose, urinary tract or bowel.

Also known as:

  • Warfarin
    (Coumadin®, Jantoven®, Marevan®, Waran®)
  • Acenocoumarol / nicoumalone
  • Phenindione   
  • Dalteparin sodium
  • Enoxaparin sodium
  • Tinzaparin sodium
  • Fondaparinux
  • Heparin
  • Dabigatran
  • Rivaroxaban
  • Apixaban

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