Some foods and other items you consume can change the way your warfarin works. These include:

  • Foods with vitamin K

  • Some herbals and over-the-counter products

  • Multi-Vitamins

  • Nutritional shakes

  • Alcohol

Vitamin K

Vitamin K is common to many foods. It is very common in green leafy vegetables. Eating large amounts of foods high in vitamin K can reduce the effects of Warfarin or Coumadin®.

If you eat foods that are high in vitamin K, it is vital to eat the same amounts of these foods each week. Keep a log of how many servings and how often you eat foods high in vitamin K. This will help you make sure you are eating the same amounts each week.

Foods High in Vitamin K

  • Kale

  • Spinach

  • Greens (turnip, mustard, beet, dandelion)

  • Collards

  • Swiss chard

  • Parsley (okay as garnish)

  • Brussel sprouts

  • Cabbage

  • Broccoli

  • Watercress

  • Onions (spring or scallions, tops & bulb)

  • Lettuce (green leaf, endive, romaine)

  • Asparagus

  • Soybeans and edamame

Other vegetables, fruits, cereals, dairy products, eggs, and meat contain smaller amounts of vitamin K.

Remember to Eat the same amounts of foods high in vitamin K each week.

Note: One serving of a high vitamin K food = ½ cup cooked or 1 cup raw.

Herbals and Over the Counter (OTC) Products

Talk with your doctor or pharmacist if you take any of these herbals or over-the-counter products. Also talk to them before starting or stopping any of the products below.

Increases Bleeding Risks

  • Fenugreek

  • Feverfew

  • Garlic (capsules)

  • Ginkgo biloba

  • Omega-3 fatty acids

  • Vitamin E

Increases Clot Risk

  • Ginseng

  • St. John’s Wort

  • Coenzyme Q10

  • Green tea


Multi-Vitamins likely contain vitamin K and vitamin E. If you do take a multi-vitamin, take your dose every day. If you do not take your multi-vitamin every day, you may reduce how well your warfarin works. Talk with your doctor or pharmacist before starting or stopping any multi-vitamins. Think about getting a multivitamin that contains no vitamin K.

Nutritional Shakes

Nutritional shakes may have high amounts of vitamin K per serving. If you will be starting one of these products tell your warfarin manager. These drinks have vitamin K. This is not a complete list.

  • Boost®

  • Glucerna®

  • Carnation Breakfast Essentials®

  • Slim Fast®

  • Ensure®

  • Kellogg’s Special K Protein Shake®

Cranberry Juice

Cranberry juice might increase risk for bleeding. Limit your intake of cranberry juice to no more than 16 ounces or 2 cups per day.


Drinking more than 2 drinks per day every day or binge drinking can greatly increase your risk for bleeding. Limit alcohol to no more than 1 drink per day, or no more than 1-2 drinks on a special occasion.

What equals 1 drink?

  • Light beer = 12 fluid ounces or 1.5 cups

  • Wine = 5 fluid ounces or ½ cup

  • Hard liquor = 1.5 fluid ounce or 1 shot

If you are a UW Health patient and have more questions, please contact UW Health at one of the phone numbers listed below.

Nutrition clinics for UW Hospital and Clinics (UWHC) and
American Family Children’s Hospital (AFCH)
(608) 890-5500

Nutrition clinics for UW Medical Foundation (UWMF)
(608) 287-2770

You can also visit our website at: