Food Interactions
Food Effect on INR Recommendations/Comments Alcohol > ↓↑ Increases INR with binging, decreases INR with chronic use Cranberry >0 There is NO significant interaction (see FAQs for more info) Ensure/Boost >↓ Contains ~25% of daily vitamin K and usually only significant if consuming several servings per day Goose Liver >↓ Avoid due to unpredictable influence of vitamin K2 Grapefruit Juice >0 No significant interaction Green Tea >↓ May lower INR in large (i.e. >1 gallon/day) quantities Liver Meats >↓ OK to eat, but treat like a vitamin K food Mango >↑ Avoid consumption of all foods containing mango as the nature of the interaction is unclear and is variable from patient to patient. Nopales (Cactus) >↓ OK to eat, but treat like a high vitamin K food Soy Products ↓ OK to eat, but treat like a vitamin K food
Supplement Interactions
Supplement Effect on INR Recommendations/Comments CoQ10 > ↓↑ Structurally similar to Vitamin K and therefore may need modest warfarin dose adjustment: Check INR within 2 weeks of starting supplement Danshen >↑ Dong Quai >↑ Coumarin derivative Flaxseed >↓ May impair absorption of warfarin--separate administration Ginseng >↓ Goldenseal >↓ Kava Kava >↑ Psyllium/Fiber >↓ May impair absorption of warfarin--separate administration Quinine/Quinidine >↑ Red Yeast Rice >↑ St Johns Wort >↓ Vitamin E >↑ Vitamin K ↓ Be consistent with supplements and multivitamins containing vitamin K
Increased Risk of Bleeding due to Antiplatelet Effect
Feverfew Fish Oil/Omega 3 Fatty Acids Garlic Ginger Ginkgo Turmeric/Curcumin
Warning in Coumadin Package Insert:
Exercise caution when botanical (herbal) products are taken concomitantly with COUMADIN. Few adequate, well-controlled studies evaluating the potential for metabolic and/or pharmacologic interactions between botanicals and COUMADIN exist.
Due to a lack of manufacturing standardization with botanical medicinal preparations, the amount of active ingredients may vary. This could further confound the ability to assess potential interactions and effects on anticoagulation.
Monitor the patient's response with additional INR determinations when initiating or discontinuing any botanicals.