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The eMC  

Last Updated 31 Jul 2015

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Warfarin 1mg tablets

Warfarin (war-fur-rin) is a medicine which is used in cerebral transient ischaemic attacks, prevention of blood clots and treatment of blood clots.

The information in this Medicine Guide for Warfarin varies according to the condition being treated and the particular preparation used.

There are 5 preparations of Warfarin available. If Warfarin 1mg tablets is not the preparation you are looking for, please select from the drop down list below.

Select your preparation (type) of Warfarin

Warfarin 1mg tablets

Information specific to Warfarin 1mg tablets when used in Blood clotting

Your medicine

Warfarin belongs to a class of medicines called anticoagulants. Warfarin is used to prevent blood clots from forming. It may also be used to treat blood clots which have already formed. Warfarin works by slowing the production of some of the chemicals in your body that are needed for blood clotting.

Some people can be prone to forming blood clots in their blood vessels so they are given anticoagulants like Warfarin to stop this from happening. Blood clots can block blood vessels in the brain or heart and cause a stroke or a heart attack.

Some medical conditions increase the chances of blood clots forming. These are conditions like heart-valve disease or certain types of heart rhythm problems. People with these types of conditions will often be prescribed Warfarin to prevent clots from forming. People who have a history of blood clots forming may also be given Warfarin even if there isn't a known illness that may be causing them.

While you are taking Warfarin, you will have to go for regular blood tests to check how long it takes your blood to clot. This test is called an INR test. You will receive a booklet telling you about the test and you can keep a record of your appointments in it. Depending on the results of each test, your dose of Warfarin may be changed slightly. Sometimes you may be asked to take slightly more Warfarin each day until the next test. On other occasions you may be asked to take slightly less or stay on the same dose. Once the INR has stabilised in the target range, you may be asked to stay on the same dose until treatment is no longer required. These small dose changes help to make sure that your blood clotting time has been changed to the right level by the Warfarin.

Warfarin will increase the time taken for your blood to clot. Because of this it is very important that you take care in situations where you have received an injury. You must get immediate medical attention if you are bleeding a lot or it is taking a long time for the bleeding to stop. You must also get medical help if you have a hard blow to the head because you may have bleeding inside your head without knowing it.

Other information about Warfarin:

Do not share your medicine with other people. It may not be suitable for them and may harm them.

The pharmacy label on your medicine tells you how much medicine you should take. It also tells you how often you should take your medicine. This is the dose that you and your prescriber have agreed you should take. You should not change the dose of your medicine unless you are told to do so by your prescriber.

If you feel that the medicine is making you unwell or you do not think it is working, then talk to your prescriber.

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When to take your medicine

Some medicines work best if they are taken at a specific time of day. Getting the most benefit from your medicine can also be affected by what you eat, when you eat and the times at which you take other medicines.

Specific information on when to take Warfarin can be found in the Patient Information Leaflet that comes with this medicine or on the medicine label. You can also ask your doctor or pharmacist for information about when to take your medicine.

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How to take your medicine

Some medicines have specific instructions about how to take them. This is because they work better when taken correctly. These instructions can include getting the right dose and special instructions for preparing the medicine.

Specific information on how to take Warfarin can be found in the Patient Information Leaflet that comes with this medicine or on the medicine label. Alternatively, you can request information about how to take your medicine from your doctor or pharmacist.

If you are having problems taking this form of Warfarin, you should talk to your prescriber or pharmacist. They may be able to give you advice on other ways to take your medicine or other preparations that are easier for you to take.

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Taking too much of your medicine

Taking extra doses of some medicines can be harmful. In some cases even one extra dose can cause you problems. If you take extra doses of your medicine, you must get medical advice immediately. You may need a test to assess the effect of taking extra doses. This is because the effects of taking too much medicine are very complex so it is very important that you seek medical advice.

Contact your prescriber, pharmacist, specialist clinic or call 111 for advice.

Make sure you take all of your medicine containers with you if you are advised to go to hospital.

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Stopping your medicine

If you are having any problems taking your medicine you must speak to your prescriber. If you are not having any problems taking this medicine then do not stop taking it, even if you feel better, unless advised to do so by your prescriber.

If you are in any doubt, contact your prescriber, pharmacist, specialist clinic or call 111.

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Looking after your medicine

The instructions on how you should keep your medicine are on the pharmacy label. It is a good idea to keep your medicine in the original container. This will help to keep your medicine in the best condition and also allow you to check the instructions. Do not take the medicine if the packaging appears to have been tampered with or if the medicine shows any signs of damage. Make sure that the medicine is out of the sight and reach of children.

Specific information on how to look after Warfarin can be found in the Patient Information Leaflet that comes with this medicine or on the medicine label. Alternatively, you can request information about how to look after your medicine from your doctor or pharmacist.

You must not take the medicine after the expiry date shown on the packaging. If you have any unused medicine, return it to your pharmacist who will dispose of it safely.

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Whether this medicine is suitable for you

Warfarin is not suitable for everyone and some people should never use it. Other people should only use it with special care. It is important that the person prescribing this medicine knows your full medical history.

Your prescriber may only prescribe this medicine with special care or may not prescribe it at all if you:

Furthermore the prescriber may only prescribe this medicine with special care or may not prescribe it at all for a child.

As part of the process of assessing suitability to take this medicine a prescriber may also arrange tests:

  • to check that this medicine is having the desired effect
  • to confirm that this is the right dose

Over time it is possible that Warfarin can become unsuitable for some people, or they may become unsuitable for it. If at any time it appears that Warfarin has become unsuitable, it is important that the prescriber is contacted immediately.

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A medicine is only made available to the public if the clinical trials have shown that the benefits of taking the medicine outweigh the risks.

Once a medicine has been licensed, information on the medicine's effects, both intended and unintended, is continuously recorded and updated.

Some side-effects may be serious while others may only be a mild inconvenience.

Everyone's reaction to a medicine is different. It is difficult to predict which side-effects you will have from taking a particular medicine, or whether you will have any side-effects at all. The important thing is to tell your prescriber or pharmacist if you are having problems with your medicine.

The frequency of these side-effects is unknown

If you feel unwell or if you have concerns about a side-effect, you will need to seek advice. If you feel very ill, get medical help straight away. Contact your prescriber, pharmacist, nurse or call 111.

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Taking other medicines

If you are taking more than one medicine they may interact with each other. At times your prescriber may decide to use medicines that interact, in other cases this may not be appropriate.

The decision to use medicines that interact depends on your specific circumstances. Your prescriber may decide to use medicines that interact, if it is believed that the benefits of taking the medicines together outweigh the risks. In such cases, it may be necessary to alter your dose or monitor you more closely.

Tell your prescriber the names of all the medicines that you are taking so that they can consider all possible interactions. This includes all the medicines which have been prescribed by your GP, hospital doctor, dentist, nurse, health visitor, midwife or pharmacist. You must also tell your prescriber about medicines which you have bought over the counter without prescriptions.

The following medicines may interact with Warfarin:

The following types of medicine may interact with Warfarin:

If you are taking Warfarin and one of the above medicines or types of medicines, make sure your prescriber knows about it.

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Complementary preparations and vitamins

Medicines can interact with complementary preparations and vitamins.

Make sure you tell your prescriber the names of all the complementary preparations and vitamins that you are taking or are planning to take.

Your prescriber can then decide whether it is appropriate for you to take combinations that are known to interact.

In the case of Warfarin:

If you have been prescribed Warfarin you should only take something on the above list on the specific advice of your prescriber or pharmacist.

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Driving and operating machinery

When taking any medicine you should be aware that it might interfere with your ability to drive or operate machinery safely.

Like all medicines Warfarin can cause side effects. You should see how this medicine affects you and then judge if you are safe to drive or operate machinery. If you are in any doubt, talk to your prescriber.

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Medicines can interact with certain foods. In some cases, this may be harmful and your prescriber may advise you to avoid certain foods.

In the case of Warfarin:

  • this medicine interacts with cranberry juice
  • you must inform your prescriber or dietician if you are having any major changes in your diet
  • this medicine may be affected by vitamin K from your food. Foods containing high levels of vitamin K include: liver, broccoli, brussels sprouts and green leafy vegetables. For more information speak to your prescriber or dietician
  • this medicine interacts with grapefruit juice

For more advice speak to your prescriber, dietitian or pharmacist.

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Alcohol can interact with certain medicines.

In the case of Warfarin:

You should seek advice from your prescriber as to whether you may drink alcohol while taking this medicine.

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Family planning and pregnancy

Most medicines, in some way, can affect the development of a baby in the womb. The effect on the baby differs between medicines and also depends on the stage of pregnancy that you have reached when you take the medicine.

In the case of Warfarin:

  • you must not take Warfarin during pregnancy. If you could become pregnant, you must use effective contraception during treatment

You should discuss your personal circumstances with your doctor if you are pregnant or want to become pregnant. This is so that together you can make a decision about what treatment you may need during your pregnancy.

You should discuss whether there are any other medicines which you could take during pregnancy which would treat your condition.

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Certain medicines can pass into breast milk and may reach your baby through breast-feeding.

In the case of Warfarin:

  • this medicine may be used by women who are breast-feeding

Women who are planning to breast-feed while having Warfarin must inform their doctor or midwife.

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Ingredients of your medicine

Medicines contain active ingredients. They may also contain other, additional ingredients that help ensure the stability, safety and effectiveness of the medicine. They are also added to improve the medicine's taste and appearance and to make it easier to take. Some may be used to prolong the life of the medicine.

This medicine contains warfarin.

We are unable to list all of the ingredients for your medicine here. For a full list, you should refer to the patient information leaflet that comes with this medicine. You should check that you are able to take the ingredients of your medicine, especially if you have any allergies. You should also check whether any of these ingredients are known to have side-effects.

If you are not able to take any of the ingredients in your medicine, talk to your prescriber or pharmacist to see if they can suggest an alternative medicine. If you have reacted badly to Warfarin before, do not take Warfarin. Talk to your prescriber, pharmacist or nurse as soon as possible.

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Warfarin, Version 12, last updated 31 Jul 2015