Warfarin (Coumadin) interactions: Which supplements should I avoid?

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Warfarin (Coumadin) interactions: Which supplements should I avoid?


Can certain medications and dietary supplements impair the effect of warfarin (Coumadin)?



Yes. Several medications and dietary supplements can affect the way warfarin (Coumadin) works in your body. For example, there's evidence that vitamin E has blood-thinning effects and may increase your risk of bleeding. Tell your doctor before taking any new medications, including herbal supplements and over-the-counter remedies. Other supplements and herbal medications known to affect warfarin (Coumadin) include:

  • Arnica
  • Bilberry
  • Butcher's broom
  • Cat's claw
  • Dong quai
  • Feverfew
  • Forskolin
  • Garlic
  • Ginger
  • Ginkgo
  • Horse chestnut
  • Inositol
  • Licorice
  • Melilot (sweet clover)
  • Pau d'arco
  • Red clover
  • St. John's wort
  • Sweet woodruff
  • Turmeric
  • Willow bark
  • Wheatgrass

Also, you should avoid taking aspirin and frequent or high doses of acetaminophen (Tylenol, others), which can increase the effects of warfarin and cause bleeding problems. Certain antibiotics also can interfere with the effect of warfarin, so be sure to check with your doctor before starting a new antibiotic.

Last Updated: 08/22/2007
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