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Warfarin Supplement Interactions -- bottle of pink warfarin tablets


Yes, the effectiveness of warfarin (Coumadin), anisindione (Miradon) and other anticoagulant drugs prescribed to prevent blood clots can be impacted by taking supplements. Because it can be affected by a large number of herbs, supplements and foods, it's important to consult your physician before taking any supplement with warfarin.

Below are some examples of supplements that may potentially interact with warfarin. Some increase or decrease the breakdown warfarin in the body, which, correspondingly, may reduce or increase the effects of warfarin. Others have their own blood-thinning or clot-promoting effects, which, correspondingly, may increase or reduce the effectiveness of warfarin. More details can be found by clicking on the links below. Also, discussed below are supplements that can interact with, or be affected by, the non-steroidal anti-inflammatory drug (NSAID) aspirin.

Supplements that may increase warfarin's blood-thinning effect by inhibiting its breakdown include:

Supplements that may increase warfarin's blood-thinning effect due to their own blood-thinning effect include:

Supplements that may reduce warfarin's blood-thinning effect by increasing its breakdown include:

Supplements that may promote clot formation, reducing the blood-thinning effects of warfarin, include the following:

Supplements that may affect, or be affected by, aspirin (another common blood thinner):

Vitamins that may affect aspirin:

  • Vitamin E: High-dose vitamin E (~800 mg daily) may increase the blood thinning effects of aspirin and increase the risk of bleeding.

Vitamins and minerals that may be affected by aspirin:

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