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CAUTION!Many drugs interact with warfarin. To prevent problems with clotting or bleeding, patients taking anticoagulants should consult with health care professionals before adding or deleting medicines from their drug regimens.
The patient is instructed to observe for signs of bleeding such as epistaxis, bleeding gums, hematuria, hematochezia, hemetemesis, melena, and bleeding into the skin (ecchymosis, purpura, or petechia). The importance of regular blood tests (to assess the prothrombin time and international normalized ratio) and medical follow-up is stressed. Maintaining constant intake levels of foods containing vitamin K also is stressed, as intermittent intake can result in widely varied coagulation levels. The patient should wear or carry a medical identification tag listing the prescribed drug, dosage, and frequency of administration. Patients who have mild to moderately elevated INRs should be treated with vitamin K; patients who have serious bleeding and warfarin poisoning should be treated emergently with infusions of prothrombin complex concentrate, factor IX complex concentrate, and recombinant activated factor VII. If these are not readily available, fresh frozen plasma may be used.