Warfarin Herbal Drug Interactions

Medical research indicates that warfarin may interact with certain herbal products. Those that:

  • Increase warfarin’s effect may increase your risk for bleeding
  • Decrease warfarin’s effect may increase your risk for forming blood clots

This list is a good reference but may not be complete. You should speak with your physician or pharmacist before taking any herbal or natural products or if you are already taking them.

Herbal products to avoid while taking warfarin

It is recommended that you avoid taking any of the following herbal products at any time while you are on warfarin therapy.

Herbal products that increase warfarin’s effects

These herbal products may increase your risk for bleeding:

  • Cranberry juice: Avoid doses greater than 1 cup (8 ounces) a day
  • Danshen
  • Dong quai
  • Garlic extract
  • Ginkgo biloba
  • Glucosamine/chondroitin
  • Grapefruit juice: Avoid doses greater than 1 cup (8 ounces) a day
  • High-dose vitamin E: Avoid doses greater than 400 IU a day
  • Melatonin
  • Vitamin A: Avoid doses greater than 10,000 IU a day

Herbal products that decrease warfarin’s effects

These herbal products may increase your risk for forming blood clots:

  • Coenzyme Q10
  • Ginseng
  • Green tea: Drink a consistent amount and use the same brand and method of brewing.
  • Soy: May use but your doctor may monitor your INR levels closely when you start or stop soy products
  • John’s wort

Herbal products that may interact with warfarin

For the following herbal products, there is limited evidence to show that they may interact with warfarin. Because these products may increase your risk for bleeding, you need close monitoring while taking these supplements:

  • Bromelain
  • Devil’s claw
  • Evening primrose
  • Fenugreek
  • Feverfew
  • Fish oil
  • Flaxseed oil
  • Ginger
  • Horse chestnut
  • Kava
  • Papain
  • Red clover
  • Saw palmetto
  • Sweet clover
  • Sweet woodruff

Make an appointment for primary care

Talk with your doctor about integrating complementary or alternative therapies into your care. Need a primary care doctor? Find a doctor and make an appointment to begin your journey to wellness.