Eating Tips to Follow While Taking Warfarin


Alcohol: Alcohol can change your response to warfarin. Discuss alcohol use with your healthcare provider.

Avocados: Avocados are high in vitamin K, although the amount varies from avocado to avocado. Vitamin K content in guacamole can varies even more.

Daily multivitamins: Some daily multivitamins contain vitamin K. Check all vitamins you take carefully. Inform your doctor if your daily vitamin contains vitamin K.

Dried basil, thyme, and oregano: These dried herbs contain high levels of vitamin K. However, a teaspoon of these herbs in their fresh form contain only a small amount and can be used.

Foods packed in oil: Watch out for foods normally low in vitamin K but packed in oil, such as tuna fish, especially when the type of oil is unknown. It is best to use canned items packed in water.

Grapefruit and grapefruit juice: Grapefruit and grapefruit juice decrease the body’s ability to metabolize warfarin.

Store-bought margarine: Store-bought margarine contains unknown amounts of various vegetable oils. As a result, the amount of vitamin K in these foods is unpredictable. Use small amounts of butter instead of margarine.

Store-bought mayonnaise: Store-bought mayonnaise contains unknown amounts of various vegetable oils and therefore has an unpredictable vitamin K content. Mayonnaise should be homemade with oils that are lower in vitamin K. If store-bought products are used, they should be the “light” variety with only small portions consumed.

Store-bought salad dressings: For the same reasons as with margarine and mayonnaise, be cautious of store-bought salad dressings. Homemade dressings are preferred.

Vitamins A, E, and possibly C: These vitamins may also affect how your warfarin works. Discuss taking vitamin supplements with your healthcare provider.

- Exposing your cooking oils to sunlight or fluorescent light destroys about 85% of vitamin K.

- Expose oils high in vitamin K to light for at least 48 hours by placing them in a transparent container in the sunlight. Do not open the container to the air because oxygen will cause the oil to oxidize.

- The vitamin K content of food is not altered by cooking or gamma radiation.


Use caution with herbal supplements as they may interfere with warfarin. The following herbs have been reported to affect warfarin activity or to affect blood clotting in other ways:

  • Alfalfa

  • Angelica

  • Aniseed

  • Arnica

  • Asafoetida

  • Chamomile

  • Echinacea

  • Fenugreek

  • Feverfew

  • Garlic

  • Ginger

  • Ginkgo biloba

  • Ginseng

  • Horse chestnut

  • Melilot

  • Prickly ash

  • Quassia

  • Red clover

  • Saint John’s wort

  • Saw palmetto

  • Sweet woodruff

  • Tonka beans

Learn more about vitamin K's interaction with warfarin