Key points about anticoagulants

  • Anticoagulants are medicines that prevent blood clots from forming and stop existing clots from growing bigger.
  • They're used for conditions including deep vein thrombosis (DVT), pulmonary embolism (PE) and atrial fibrillation (to prevent stroke). They are also used to prevent DVT and PE after hip or knee surgery.   
  • Find out about the different anticoagulants and possible side effects.
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Anticoagulants are often called ‘blood thinners’ but they actually work by interrupting the clot-forming process and increasing the time it takes for blood clots to form. This helps prevent blood clots from forming and stops existing clots from growing bigger. 

  • Blood clots are clumps of blood that can be useful for stopping bleeding wounds.
  • Blood clots can also block blood vessels. Blood vessels transport blood around the body, if they're blocked, blood won’t be able to reach places they need to including your heart or the brain. Learn more about blood clots.

You're at risk of developing blood clots if you:

  • are at increased risk of having a stroke
  • have cancer or are receiving some types of treatment for cancer
  • are pregnant or taking some types of oral contraceptives
  • have been sitting for long periods, eg, during a long flight or drive
  • have had hip or knee replacement surgery recently or are in hospital for a long time.

Anticoagulants available in Aotearoa New Zealand

Anticoagulants that come as tablets or capsules Anticoagulants given by injection
Dabigatran, rivaroxaban and apixaban are also called novel oral anticoagulants (NOACs). These are commonly used in hospital. Some people may be given these to inject at home. If you need to do this, your healthcare provider will show you how.

Anticoagulants have a variety of uses, including:

  • For people with atrial fibrillation, because atrial fibrillation increases the risk of stroke. A stroke happens when a blood clot forms in your heart and travels to your brain (usually due to an irregular heart rhythm known as atrial fibrillation or AF).
  • For people with artificial heart valves, to protect clots developing on the valves. 
  • For the prevention and treatment of deep vein thrombosis, where blood clots form in veins deep within your legs and pelvis. From here, the clots can travel to your lungs and cause a pulmonary embolism.

How long you will need to take an anticoagulant for will depend on what you're taking it for. Some people only need it for a few weeks (eg, after surgery), or for a few months (eg, for deep vein thrombosis). Others may need to take an anticoagulant for the rest of their lives (eg, people with atrial fibrillation or a mechanical heart valve). Your doctor will advise on what's best for you.

Video: How do novel anticoagulants work?

The following animation describes how anticoagulants (eg, dabigatran, rivaroxaban and apixaban) work in your body.

(British Heart Foundation, UK, 2018)

When taking anticoagulants, it's important to use the medicine safely and correctly. The benefits of these medicines need to be carefully balanced with possible side effects. Not enough anticoagulation can lead to a blood clot or stroke, but too much anticoagulation can lead to serious bleeding.

Here are some things to know when you're taking anticoagulants. Other things may be important as well, so ask your healthcare provider what you should know about.

  • Anticoagulants increase your risk of bleeding: Avoid contact sports, tattoos, piercings and deep massage. It's also important to look out for signs of bleeding and report them to your healthcare provider. Signs include bleeding gums, red or black bowel motions and if you are bruising easily.
  • Avoid injury: To reduce your risk of severe bleeding if you're injured, try to avoid cuts, grazes and injuries by taking care when brushing your teeth and shaving (consider using a soft toothbrush and an electric razor) and protecting yourself when gardening, sewing or playing sports. You may also be advised to avoid contact sports because of the risk of excessive bleeding.
  • Tell all healthcare providers that you're taking anticoagulants (eg, your doctor, dentist, pharmacist or podiatrist). You may need to stop taking your anticoagulant before surgery, dental care and some tests.
  • Other medicines: Anticoagulants can interact with some medicines and herbal supplements, so check with your doctor or pharmacist before starting them and before starting any new products. This includes over-the-counter anti-inflammatories including diclofenac (eg, Voltaren Rapid), ibuprofen (eg, Nurofen) and naproxen (eg, Naprogesic).
  • Pregnancy: Warfarin, dabigatran, rivaroxaban and apixaban aren't usually given to pregnant women. If you're taking any of these medicines and could become pregnant, you should make sure you use contraception. If you're on anticoagulants and find out you're pregnant (or you're planning a pregnancy) talk to your GP or anticoagulant clinic about stopping or changing your prescription.

You might bleed or bruise more easily while you're taking anticoagulants.

  • Be careful when shaving, clipping fingernails, brushing and flossing your teeth, or playing sports.
  • Avoid new tattoos and piercings as these can cause bruising and bleeding.
  • If you have a fall or hurt your head or body, get medical attention immediately, even if you feel okay.
  • Some types of bleeding are more serious than others. If bleeding concerns you, is heavier than usual or takes an unusually long time to stop, you should talk to your healthcare provider quickly.

Signs of severe bleeding

Contact your healthcare provider urgently if you have any of the following signs of bleeding:

  • Becoming pale, very weak and tired, or short of breath.
  • Any bleeding from your gums.
  • Cuts or nosebleeds that won’t stop.
  • Blood in your stools (poo) – black, tarry stools.
  • Blood in your urine (pee) – pink, red or brown-coloured urine.
  • Heavy periods (menstrual bleeding).
  • Coughing up blood.
  • Vomiting up something that looks like coffee grounds.

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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