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Warfarin Clinic

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Information for patients taking Warfarin

Warfarin Clinic

  • Information

We advise you to book appointment with one of our expert GP to check and monitor your INR blood test at our centre.

What is Warfarin?

Warfarin is an anticoagulant or a blood thinner, reducing the formation of blood clots. It is used to treat or prevent blood clots in veins or arteries.

You will need to book an appointment to be seen at the centre where one of our doctors will explain Warfarin & INR checks.

How do I take my anticoagulant?

Your anticoagulant must be taken once a day, at about the same time, on an empty stomach and washed down with a full glass of water.

If you miss a dose or took the wrong dose by mistake, make a note of this in your booklet and contact your doctor. Take your normal dose the next day. If you exceeded your normal dose, please contact your local anticoagulant clinic for advice.

You may be given a number of different strength tablets to make up your dose. It is important to familiarise yourself with the varying strengths and colours of the tablets you may need to ingest.

In the UK, the colours of Warfarin tablets are:

0.5mg (500 micrograms) = WHITE
1mg = BROWN
3mg =BLUE
5mg = PINK

Monitoring anticoagulant intake

You must undergo a regular blood test called an International normalised ratio test (INR). This is a standard test measuring the length of time your blood takes to clot. Normally blood that is not anti-coagulated has an INR of approximately 1.0.

The dose of the anticoagulant you will require depends on your INR test result. If your result is out of the range appropriate for your condition, then your dose of anticoagulant will be increased or decreased accordingly. The anticoagulant dose required to achieve the target INR varies from patient to patient.

Repeat Prescriptions

It is important to perform a routine check-up each time you request or receive a supply of oral anticoagulants. This will include: reviewing your blood test results and dose information to make sure it is safe to supply you with more tablets.

When you request an additional prescription, you will be requested to provide information about your INR test results and current dose of oral anticoagulant. This information is to be recorded and collected in your anticoagulant folder.

Your community pharmacist will also request to view this information upon dispensing of prescription. Make sure that you do not run out of tablets and always have as least a week’s supply on hand.

Serious Side Effects

Please be advised that the most serious side effect of anticoagulants is bleeding. If you experience any of the following symptoms, please seek medical attention and have an urgent INR test immediately!

1) Prolonged nosebleeds – more than 10 minutes
2) Blood in vomit
3) Passing blood in your urine or faeces
4) Severe spontaneous bruising
5) Unusual headaches

For Women

Seek attention if you experience an increased flow of blood during your menstruation cycle or any other vaginal bleeding. If you cut yourself, apply firm pressure to the site for at least five minutes using a clean, dry dressing.

Seek immediate medical attention if you:

1) Are involved in a major trauma
2) Suffer a significant blow to the head
3) Are unable to stop the bleeding

Dental Check-ups

You can still visit the dentist as usual. Most often, your dental treatments can proceed as normal without any need to stop or adjust your anticoagulant. However, your dentist will require viewing a recent INR test result to ensure that it is safe to provide treatment.

Your dentist will provide you with a leaflet containing additional advice. Please contact your dentist before your appointment in case they require you to perform an extra blood test.

Factors that can affect anticoagulation

Many medicines can interact safely with anticoagulants. If you happen to begin or end the use of another medication during your course of anticoagulants, your doctor may advise you to perform a blood test within five to seven days of starting the new medication. This precautionary measure is to simply make sure that your INR remains within its desired range.

If you plan on buying over-the-counter medicines, including alternative remedies, make sure you inform the pharmacist that you are on oral anticoagulants and show them your alert card. This will help them advise you on the medicines you can safely take.

 You should not take aspirin unless it has been specifically prescribed by your GP. It is also advisable to avoid any other non-steroidal anti-inflammatory drugs like diclofenac or ibuprofen.

Please note that some of these can be bought over the counter at pharmacies with names such as Nurofen. Paracetamol and codeine-based painkillers are acceptable, although please be advised that some paracetamol ‘plus’ products contain aspirin.

There are some medicines that may affect the way anticoagulants work. These include:

1) Prescription medicines
2) Antibiotics
3) Non-steroidal anti-inflammatory drugs
4) Oral contraceptives
5) Corticosteroids
6) Over the counter medicines (these can be bought without a prescription)
7) Herbal remedies


It is extremely to eat a well-balanced diet. Consult your doctor if you need to go on a diet to lose weight. Any major changes in your diet may affect how your body responds to your anticoagulant medication.

These following foods are important for a healthy diet but may result in lowering your INR result. These are examples of foods rich in vitamin K:

1) Green, leafy vegetables
2) Chickpeas
3) Egg Yolks
4) Liver
5) Mature and blue cheeses
6) Avocado
7) Cereals containing wheat bran and oats
8) Olive oil

Make sure you maintain the same quantity of these foods on a regular basis. Any change in vitamin K intact will have an effect on your INR result. Drinking cranberry juice can also have an effect on your INR. Therefore try to avoid it altogether if possible. If your diet changes drastically over a seven-day period, you must get an INR test done.


It is highly recommended to never exceed the national guidelines for alcohol consumption. Men are allowed to ingest up to three units of alcohol per day and up to two units per day for women. Remember, it is extremely dangerous to ‘binge drink’ while taking anticoagulants.


Oral anticoagulants can affect the development of a baby in early stages of pregnancy. If you are on anticoagulants, consult your doctor before trying to conceive. Women, who become pregnant while on Warfarin, must urgently set up an appointment with a doctor.

Breast Feeding

You may breast feed whilst taking anticoagulant medication.


Women may experience heavier periods whilst taking oral anticoagulants and may wish to discuss these side-effects with their GP or anticoagulant nurse.

Copyright by First Health Medical Centre 2017. All rights reserved.