Anticoagulants
It is important for everyone's blood to clot so that bleeding from cuts and other accidents will eventually stop. But in some people it is important to slow this process down by making the blood ‘thinner’. These people take medications known as anticoagulants — medicines which interfere with the blood's natural clotting process. These medicines do not affect any other function of blood, such as carrying oxygen or fighting infection.
The most common anticoagulant medication is called warfarin. It may be needed for a short time or, in many cases, for life.
Common reasons for taking anticoagulant medications are:
- past history of abnormal blood clot (e.g. a clot in the leg or on the lung);
- irregular heartbeat;
- artificial heart valve; and
- (in some cases only) after a heart attack or stroke.
Those taking anticoagulants need regular blood checks to make sure that their blood is not too thin, which could put them at risk of abnormal bleeding. A measure known as INR (international normalised ratio) has been developed to compare the rate of blood clotting between someone taking anticoagulants and someone who is not.
The INR of a healthy person not taking warfarin is 1.0. The ‘thinner’ the blood and the longer it takes to clot, the higher the INR. For most people on anticoagulants the INR needs to be maintained somewhere between 2.0 and 3.0.
Certain foods, particularly those containing high amounts of Vitamin K such as green leafy vegetables, can affect your INR. It is not that you shouldn’t eat these foods, but your intake should not vary widely. Tell your doctor if you are making major changes to your regular diet.
Taking other medications can affect the rate of blood clotting in people taking warfarin. Warfarin has more potential for interacting with other medicines than just about any other medication, so always discuss with your doctor or pharmacist before taking any new medication.
Last Reviewed: 11 February 2009
