Anticoagulation service

The anti-coagulation clinic is an outpatient service located in Reception 2

Who is this service for?
This is a nurse-led service for people who are being treated with anticoagulation therapy.

We provide care for adults with oral anticoagulation requirements including the newer novel anticoagulants.

These drugs decrease the clotting ability of the blood and prevent clots from forming in the blood vessels. They will not dissolve clots that have already formed but help stop clots becoming larger and reduce the risk of further clots.

Reducing the blood’s ability to clot is important in preventing conditions such as strokes and heart attacks. Anticoagulants are given to people who have a history of these conditions or who are at risk of developing them. Other high risk groups include people who have: deep vein thrombosis, pulmonary embolism, angina, atrial fibrillation (AF), cancer and artificial heart valve replacement.

What does anticoagulation treatment involve?
People taking anticoagulants need to have regular blood tests to see how well the drug is working. We will check how long it takes for your blood to clot by using a measurement called an INR (International Normalised Ratio).

We aim to keep your INR within a certain range. The results of your blood test will be written in your yellow book. If the INR level is too high, the dose will be reduced or sometimes you may need to stop the tablets for a day or two. If the INR is very low, we may increase the dose. In both cases we may ask about recent changes in your lifestyle.

The blood test is very quick and involves taking a small sample of blood from your fingertip; if your INR level is high we may need to take a sample of blood from your vein which will take longer to process.

Patients who take anticoagulants will be given a warning card which they should carry at all times and inform all health professionals that they are taking anticoagulants. Patients must also bring their yellow record book with them each time they attend the anticoagulation clinic.

How does the service work?
You will be started on anticoagulant therapy by either your hospital doctor or your GP who will refer you to this nurse led service. We would normally expect to see you within 48 hours of receiving the referral but there are occasions when it may not be possible

The first anticoagulation visit takes the longest as you will be assessed by the specialist clinician. You will be given information on anticoagulants, why you are taking it, what you should and should not do whilst taking anticoagulants and have the opportunity to ask questions about your treatment. The hospital will only provide you with a prescription for anticoagulants on your first visit. Repeat prescriptions must be obtained from your GP.

When you first start anticoagulant therapy the dose may need changing each time that your blood is tested until we find the right dose for you. This may mean that you have to attend the anticoagulation clinic regularly until your blood results stabilises and are within your target range. 

Making an appointment
Patients require a written referral to one of our clinics by their GP or by a hospital consultant.

What do I do if I need to cancel my appointment?
It is important for you to attend your anticoagulation clinic appointment to monitor your INR level. If you are unable to keep an appointment or need to speak to one of the haematology nurse specialists please telephone 020 8510 5764 and leave a brief message including your name, hospital number and a contact number. We will return your call as soon as we can.

If you require hospital transport or the advocacy services please discuss this with the doctor who referred you to the anticoagulation clinic as they will need to arrange this for you prior to attending for your first appointment.

Essential guidance for patients taking oral anticoagulant therapy
Anticoagulation therapy is safe provided that you follow the Do’s and Do not’s given below:


  • do carry your anticoagulation therapy record book with you and show it to your doctor, nurse, dentist or pharmacist before you are given any treatment or medicine
  • do take your dose of anticoagulant at the same time each day
  • do have your blood test on the day of the week specified
  • do inform us of any changes to your other medications
  • do immediately inform your doctor and the anticoagulation clinic of any bleeding e.g. from the nose, gums, urinary tract, bowel, or of any bruising
  • do inform your dentist you are on anticoagulant therapy before any treatment
  • do inform us if you think you are pregnant or trying to become pregnant.

Do nots

  • do not miss a dose of anticoagulant unless your doctor or nurse instructs you to do so – if you miss a dose in error, make a note of the date and tell the nurse or doctor when you have your next blood test, do not take an extra dose unless your nurse or doctor instruct you to
  • do not run out of tablets – always ensure you have at least a weeks supply
  • do not take aspirin or any other preparation containing aspirin unless this is prescribed by a doctor who knows that you are taking an anticoagulant
  • do not crash diet or binge – always consult your doctor about dietary changes including the use of dietary supplements or herbal remedies
  • do not drink more than moderate amounts of alcohol – changes in consumption can be very dangerous
  • do not drink cranberry juice and avoid other cranberry products such as capsules or concentrates.