Food and Supplement Interactions
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.