Print Print
CKS is no longer commissioned by the National Institute for Health and Clinical Excellence (NICE). NICE remains committed to providing a replacement service for CKS and is currently reviewing its options. In the meantime, although CKS content is now not being maintained, it still remains relevant and will continue to be made available. CKS content was generated under a programme of topic creation and update. To check if the topic you are viewing is current or out of date, please refer to the topic publication details by clicking on the 'How up-to-date is this topic?' link in the left hand menu on individual topic pages.

Anticoagulation - oral - Management
What information and advice should I give to a person receiving warfarin?

  • Advise the person taking warfarin that:
    • It is very important to have their blood tested regularly (preferably in a warfarin clinic). However, ongoing prescriptions for warfarin tablets should be obtained from their GP.
    • They should take the warfarin at the same time each day.
    • They should not miss doses, or take additional doses, without advice from a healthcare professional.
      • They must inform anticoagulant healthcare staff if they think they have taken too much warfarin or have missed any doses.
      • If a dose is accidentally missed, they should continue with the regimen as prescribed, and never take a double dose (unless specifically advised).
    • They should always carry their yellow anticoagulant treatment booklet or anticoagulant alert card (issued in hospital) with them.
  • Advise the person to inform a healthcare professional (including anticoagulant clinic staff, their GP, dentist, pharmacist, and medical or nursing staff) of changes to their lifestyle, for instance if:
    • They are pregnant or planning a pregnancy — they will need to stop taking warfarin (as it is dangerous to the fetus and pregnant women) and to start taking low molecular weight heparin.
    • They start, stop, or change the dose of other medicines. Other medicines include not only prescribed drugs, but also products that may be bought without prescription, such as aspirin and medicines containing aspirin, vitamins, food supplements, and herbal or homoeopathic remedies.
    • They require surgery or any other invasive procedure, as they may need to temporarily stop taking warfarin.
      • For surgery where there is no risk of severe bleeding, surgery can be performed with an INR of < 2.5.
      • For surgery where there is a risk of severe bleeding, warfarin should be stopped 72 hours prior to surgery. If it is necessary to continue anticoagulation because the person is at high risk of venous thromboembolism, (such as within the first 6 weeks after a deep vein thrombosis) the INR should be reduced to < 2.5 and heparin therapy should be started. (The risk for recurrent venous thromboembolism is high immediately after the initial deep vein thrombosis and declines over the subsequent period.)
      • Outpatient dental surgery (including extractions) can usually be undertaken without temporarily stopping or reducing the dose of warfarin. It is recommended that the INR is checked 72 hours before dental surgery. The risk of significant bleeding in people with a stable INR within the range 2 to 4 is very small, but the risk of thrombosis may be increased if oral anticoagulants are temporarily discontinued.
  • Advise the person to be aware of the adverse effects of warfarin and to seek immediate medical advice if:
    • Spontaneous bleeding occurs whilst on warfarin, and the bleeding does not stop or recurs. This includes bruising, bleeding gums, nosebleeds, prolonged bleeding from cuts, and blood in the urine or stools.
    • They get sudden severe back pain (may indicate spontaneous retroperitoneal bleeding).
    • They experience difficulty breathing, increased breathing rate, or chest pain (symptoms of pulmonary embolism).
  • Give the person general lifestyle information and advise that they should:
    • Seek medical advice before undertaking any major changes in diet, especially if their diet is rich in vitamin K (such as broccoli, lettuce, or spinach) — this can potentially affect control of anticoagulation.
    • Limit the amount of alcohol to a maximum of one or two drinks a day, and never binge drink.
    • Avoid activities which could cause abrasion, bruising, or cuts (for example, contact sports, gardening, sewing), or at least use protection.
    • Take extra care when brushing teeth or shaving, and consider using a soft toothbrush and an electric razor.
    • Avoid insect bites where possible and consider use of an insect repellent, as appropriate.

© NHS Institute for Innovation and Improvement