Coumarin Anticoagulants/Vitamin K-Containing Foods Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug, changing your diet or commencing any course of treatment.

Medical warning:

Very important. A change in your diet, medicine, or dosage may be necessary. Promptly consult your doctor or pharmacist.

How the interaction occurs:

When your anticoagulant ("blood-thinner") is taken with foods containing vitamin K, the vitamin K may prevent your anticoagulant from effectively preventing blood clots.

What might happen:

The beneficial effects of your anticoagulant may decrease, which may increase your risk of an unwanted blood clot.

What you should do about this interaction:

Avoid sudden changes in your diet while you are taking this medicine. Foods high in Vitamin K are of the most concern, but the best approach is to try to be consistent in your daily food choices. Do not change the amount of moderate-to-high Vitamin K-containing food in your diet (see the lists below) without first consulting your healthcare professional (e.g., doctor or pharmacist).Also, do not use a strict vegetarian diet (some greens have moderate-to-high Vitamin K content) without first consulting your healthcare professional.Some examples of foods high or moderate in Vitamin K content are listed below: High Level Vitamin K Foods (micrograms per serving listed) include Kale, fresh (547.4 micrograms per 1 cup); Swiss Chard, fresh (298.8 micrograms per 1 cup); Broccoli, frozen, boiled (248.4 micrograms per 1/2 cup); Broccoli, fresh, boiled (210.6 micrograms per 1/2 cup); Spinach, fresh (120 micrograms per 1 cup); Green or Red Leaf Lettuce (117.6 micrograms per 1 cup); Escarole, fresh (115.5 micrograms per 1 cup); Endive, fresh (115.5 micrograms per 1 cup); Cabbage, fresh (101.5 micrograms per 1 cup); Moderate Level Vitamin K Foods (micrograms per serving listed) include Mustard Greens, fresh (95.2 micrograms per 1 cup); Brussels Sprouts, fresh (77.9 micrograms per 1/2 cup); Butterhead Lettuce (67.1 micrograms per 1 cup); Watercress (42.5 micrograms per 1/2 cup); Yellow Snap Beans (41.3 micrograms per 3/4 cup); Kiwi Fruit (38 micrograms per 2 items); Asparagus, fresh (35.7 micrograms per 2/3 cup); Soybeans, dry roasted (31.8 micrograms per 1/2 cup); Split Peas, boiled (27.5 micrograms per 1/2 cup); Green Peas (27.3 micrograms per 1/2 cup); Soybean Oil (26.2 micrograms per 1 tablespoonful); Abalone, Raw (26.1 micrograms per 1/2 cup); Green Beans, cooked (25.8 micrograms per 1/2 cup). Avocados, some varieties of seaweed, and liquid nutritional supplements also contain vitamin K.Contact your doctor or pharmacist for more information. Your healthcare professionals may be aware of this interaction and may be monitoring you for it. Do not start, stop, or change your medicine or diet before checking with them first.

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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.