- Class
- Anticoagulants
- Body system
- Blood and clotting
- Brand names
- Jantoven
- Antidote or reversal
- Vitamin K (phytonadione); prothrombin complex concentrate or plasma for serious bleeding.
What is Warfarin used for?
- Prevention of stroke in atrial fibrillation
- Treatment and prevention of DVT and pulmonary embolism
- Mechanical heart valves
How Warfarin works
Vitamin K antagonist: blocks the liver's production of clotting factors II, VII, IX and X. The full effect takes several days.
Common side effects
- Bleeding
- Bruising
Report right away
- Bleeding gums, nosebleeds, blood in urine, black or bloody stools, vomiting blood
- Severe headache or sudden weakness (possible brain bleed)
- Purple, painful toes
Nursing considerations for Warfarin
- Monitor the PT/INR: the usual target is 2 to 3, higher (2.5 to 3.5) for some mechanical valves.
- Heparin or a low-molecular-weight heparin is often given until the INR is therapeutic.
- Many drug interactions: antibiotics, amiodarone, NSAIDs, aspirin and many herbal products change the INR or the bleeding risk.
Patient teaching
- Keep vitamin K intake consistent (leafy green vegetables): do not suddenly increase or stop them.
- Keep every INR appointment and tell all providers you take warfarin.
- Avoid alcohol excess and new herbal products (ginkgo, garlic, ginger and others) without asking.
- Warfarin is generally avoided in pregnancy: use reliable contraception.
This card does not list doses. Use the prescriber's order, the product label and a current drug reference for dosing, and follow your facility's policies.
Anticoagulants practice questions
NCLEX-style questions on the class Warfarin belongs to.
3 questions. Choose an answer to see the rationale.
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Which lab value is used to monitor warfarin therapy?
Show answer
Answer C: INR Warfarin is monitored with the PT/INR; the usual target is 2 to 3.
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A patient on a heparin infusion has a platelet count that dropped by more than 50% from baseline. What does the nurse suspect?
Show answer
Answer D: Heparin-induced thrombocytopenia A large platelet drop, typically 5 to 10 days after starting heparin, suggests heparin-induced thrombocytopenia, which paradoxically causes clotting.
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Which antidote should be available for a patient receiving a heparin infusion?
Show answer
Answer C: Protamine sulfate Protamine sulfate neutralizes heparin. Vitamin K reverses warfarin.
Frequently asked questions
What is Warfarin used for?
Prevention of stroke in atrial fibrillation; Treatment and prevention of DVT and pulmonary embolism; Mechanical heart valves.
What drug class is Warfarin?
Warfarin belongs to the class anticoagulants. Vitamin K antagonist: blocks the liver's production of clotting factors II, VII, IX and X. The full effect takes several days.
What are the nursing considerations for Warfarin?
Monitor the PT/INR: the usual target is 2 to 3, higher (2.5 to 3.5) for some mechanical valves. Heparin or a low-molecular-weight heparin is often given until the INR is therapeutic.
What should patients report while taking Warfarin?
bleeding gums, nosebleeds, blood in urine, black or bloody stools, vomiting blood; severe headache or sudden weakness (possible brain bleed); purple, painful toes.
What is the antidote for Warfarin?
Vitamin K (phytonadione); prothrombin complex concentrate or plasma for serious bleeding.