What Is the Antidote for Coumadin?

Kale can be a source of vitamin K to counteract Coumadin.
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  • Written By: Elizabeth West
  • Edited By: Shereen Skola
  • Last Modified Date: 15 September 2014
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Coumadin®, the brand name of warfarin, is an anticoagulant medication taken by patients who are prone to deep vein thrombosis (DVT) or other vascular disorders. Vitamin K, a fat-soluble vitamin that the body stores in limited quantities, is the antidote for Coumadin® overdose; it also contributes to vascular and bone health. Patients should avoid foods that contain vitamin K while taking the medication. Coumadin® patients should have a medical alert on their persons in case problems arise during therapy, so the antidote can be administered quickly.

An antidote acts in opposition to a substance, reversing its effect. The administration of vitamin K as an antidote for Coumadin® is usually performed orally, unless bleeding is critical. In this case, the antidote is administered intravenously, slowly at 5 to 10 milligrams over a period of thirty minutes. A transfusion of plasma is also given to replace fluids lost in heavy bleeding.

Vitamin K enables clotting factors in the blood to work properly. Without it, the proteins don't aggregate and the risk of hemorrhage rises. The body doesn't stockpile much of the vitamin, so a process called the vitamin K cycle reuses it. Coumadin® disrupts the cycle and causes K deficiency, which inhibits the formation of DVT and other thrombi. Regular testing for prothrombin time may catch an overdose before it becomes serious, so healthcare providers can adminster the antidote for Coumadin®.


The balance is tricky to maintain, and patients taking Coumadin® ideally should not ingest more than 90-120 mcg per day of vitamin K-rich foods or supplements. A warfarin overdose occurs if the patient takes too much, or there is weight loss while on the medication. Symptoms of an overdose include excessive bruising, blood in the urine or stool, and abnormal bleeding from any external wounds, the nose or gums. This is a medical emergency requiring immediate intervention and administration of the antidote for Coumadin®.

Besides the clotting issue, vitamin K may contribute to bone mineralization. Several proteins dependent on K have been identified, including osteocalcin, matrix Gla protein (MGP), and protein S. Osteocalcin works with vitamin D, and may involve K as well. Another vitamin K protein identified in 1993, Gas6, may have something to do with cell growth. Dietary K can be found in spinach, kale, broccoli, and olive and canola oils.

Healthcare providers often recommend avoiding foods rich in vitamin K during warfarin therapy since it can render Coumadin® ineffective. Patients must be monitored regularly to ensure the level of the medication does not go too high, putting them at risk for serious bleeding. They should also wear a medical alert bracelet or pendant and carry a medical alert card with them at all times. If administered quickly, the antidote for Coumadin® can reverse an overdose before fatal bleeding occurs.


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