• Too much anticoagulant medicine, a type of blood thinner that helps prevent clots.
• Other medicines, such as aspirin, NSAIDs, and some antibiotics, when you also are using anticoagulants.
• Health conditions, such as liver failure or bleeding disorders

Certain foods and dietary supplements have vitamin K. Vitamin K works against warfarin. If you eat more vitamin K, it can lower your INR. If you eat less vitamin K, it can raise your INR.

Increase or decrease oral Vitamin K administration based on the clinical situation. Parenteral Vitamin K should only be used for life-threatening bleeding and is therefore not appropriate for outpatient use.

INR levels above 4.9 are considered critical values and increase the risk of bleeding.

No special preparation is needed.

Illness, change in diet, and some medications (as mentioned above) can alter PT/INR results. Certain foods, such as beef and pork liver, green tea, broccoli, chickpeas, kale, turnip greens, and soybean products contain large amounts of vitamin K and can alter PT/INR results.