Preventing blood clots during outpatient cancer treatment

A blood clot, also called venous thromboembolism (VTE), is a blockage in a deep vein in your body.

These blood clots usually form in a deep vein in the legs, but they can also occur in other areas, such as the arms. This is called a deep vein thrombosis (DVT).

Sometimes, a piece of the clot can break off, travel to your lungs through your bloodstream, and block a blood vessel there. This is called a pulmonary embolism (PE) and can be life-threatening.

If you think you may have a blood clot, you will need urgent treatment. Go to your nearest Emergency Department (A&E) as soon as possible.

People with cancer, or those having major cancer surgery, have a higher risk of developing a blood clot. You can lower this risk by:

• staying as active as you can during your treatment
• drinking plenty of water to avoid dehydration

Your hospital doctor may also suggest a ‘blood-thinning’ medicine (called an anticoagulant) to help prevent blood clots.

Your doctor may suggest that you start taking a medicine called apixaban around the time you begin chemotherapy. 

Apixaban is a tablet that you take twice a day, about 12 hours apart. For example, you can take it at 8am (in the morning) and 8pm (in the evening). Your doctor will prescribe a low ‘clot-prevention’ dose of apixaban and advise you how long you will need to take it. For most people, this is usually while they are on chemotherapy. 

If apixaban is not suitable for you, your doctor may recommend an injection called enoxaparin instead. This is usually self-administered and taken once a day under the skin (subcutaneously). We will show you and your carer how to do the injections. We will also give you a sharps bin to dispose of used syringes. When the bin is full, seal it, fill in the label on the side, and return it to UCLH at your next appointment. Do not throw syringes or sharps bins in household waste.  

Please note that enoxaparin is of animal origin. If you have concerns about this, please speak to your doctor.

Like all medicines, anticoagulants may have potential side effects. The most common are mild bleeding or bruising, but most people do not have any problems.

Contact your GP or go to the nearest Emergency Department (A&E) straight away if you notice:

• blood in your urine or stools 
• severe or unexplained bruising 
• heavy vaginal bleeding 
• bleeding that does not stop  
• coughing up blood 

You should also go to the nearest Emergency Department (A&E) if you have had a head injury, even if you don’t lose consciousness.

Your hospital doctor (not your GP) will prescribe apixaban or enoxaparin.  

You can collect your medicine from Rowlands pharmacy at UCLH.  

We will let your GP know that you are taking this medication.

• Always tell any healthcare professional caring for you – including doctors, dentists, nurses or pharmacists – that you are taking a blood-thinning medicine. This is important because blood thinners may affect some treatments, and other treatments can affect how your blood thinner works.
• Tell your GP or hospital team if you start, stop or change any other medicines. They can then check if this may affect your blood thinner.
• Do not take herbal medicines, supplements or anti-inflammatory painkillers (such as aspirin, ibuprofen, naproxen or diclofenac) without checking first with your doctor, nurse or pharmacist.

If you have any general questions about blood-thinning medicines or clot prevention, contact your CNS or cancer pharmacist in the first instance. 

If you have a printed version of this information, you can write your CNS’s details in the space below:  

Name: .................................................................................................................................

Tel: ......................................................................................................................................

Switchboard: 020 3456 7890

NHS website:

DVT (deep vein thrombosis)

Pulmonary embolism

Cancer Research UK:

Cancer and the risk of blood clots

University College London Hospitals NHS Foundation Trust cannot accept responsibility for information provided by external organisations.