Data provided by Applied Health
side effects, nutrient depletions, herbal interactions and health notes:
• Avoid supplementing high dosages of vitamin A (over 10000 IU/day), or vitamin E (over 400 IU/day) with this medication.1
• More than 5 gms (5,000 mg) of vitamin C may reduce the absorption of Warfarin.2
• Absorption and activity of Warfarin may be decreased by iron, magnesium, and zinc. These minerals should be taken at least two hours apart from this medication.3
• If you are taking NSAIDS and Warfarin, you should consult with a physician before using chondroitin sulfate.4
• More than 60 grams of onions (2 ounces) may affect the activity of Warfarin.5
• Avoid avocado with warfarin.6
• Vitamin K and warfarin are co-dependent. Vitamin K levels must be kept at constant levels while taking warfarin.7
• Coumadin may also be affected by CoQ10, which creates a similar action as vitamin K.8
• Taking high doses of Grapefruit juice with Warfarin can produce high INRs.9
• The following herbs may contribute to blood-thinning, and should not be used with Warfarin: Angelica, anise, arnica, asafoetida, bogbean, boldo, danshen, fenugreek, feverfew, garlic, ginger, ginkgo, ginseng (Panax), horse chestnut, licorice, meadowsweet, prickly ash, passionflower, poplar, quassia, red clover, turmeric, and willow.10
• Warfarin absorption may be affected by daily use of the following herbs: Catnip, Comfrey, Gentian, Hops, Mullein, Peppermint, or Slippery elm.11
References1 Wells, PS et al., Interactions of Warfarin with drugs and food. Ann. Int. Med. 1994, 121:676-683.
1 Pronsky, Z Food Medication Interactions, 11th edition, 1999
2 Wells, PS et al., Interactions of Warfarin with drugs and food. Ann. Int. Med. 1994, 121:676-683.
2 Harris JE. Interaction of dietary factors with oral anticoagulants: Review and applications. J Am Dietet Assoc 1995;95:580-84 [review].
3 Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 284.
4 Chavez, M: Glucosamine sulfate and chondroitin sulfates. Hospital Pharmacy, 1997, 52(9): 1,275-1,285.
5 Menon, I.S. et al: Effect of onions on blood fibrinolytic activity. BMJ, 1968,3:351.
5 Pronsky, Z Food Medication Interactions, 11th edition, 1999
5 Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 284.
6 Blickstein, D et al, "Warfarin antagonism by avocado", 1991, The Lancet 337:914-915.
7 Facts and Comparisons, Clinisphere 2.0, Wolters Kluwer Company, 2000
7 Pronsky, Z Food Medication Interactions, 11th edition, 1999
7 Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 286.
8 United States Pharmacopeia Drug Index (USPDI). 8th ed. Rockville, Md: US Pharmacopeial Convention, Inc; 1988:259-268.
8 Harris JE. Interaction of dietary factors with oral anticoagulants: Review and applications. J Am Dietet Assoc 1995;95:580-84 [review].
8 Landbo C & Almdal TP [Interaction between warfarin and coenzyme Q10.] Ugeskr Laeger, 1998 May, 160:22, 3226-7.
8 Spigset O. Reduced effect of warfarin caused by ubidecarenone. Lancet 1994;344:1372-73 [letter].
9 Bartle, W. Grapefruit juice might still be factor in warfarin response (letter). American Journal of Health-System Pharmacy 1999; 56 (April 1): 676.
9 Sullivan D, et al. Grapefruit juice and the response to warfarin. American Journal of Health-System Pharmacy 1998; 55: 1581-1583.
10 Newall CA, Anderson LA, Phillipson JD. Herbal Medicines A Guide for Health-care Professionals. London: The Pharmaceutical Press, 1996.
10 Gadkari JV, Joshi VD. Effect of ingestion of raw garlic on serum cholesterol level, clotting time and fibrinolytic activity in normal subjects. J Postgrad Med 1991;37:128-31.
10 Burnham BE. Garlic as a possible risk for postoperative bleeding. Plast-Reconst-Surg 1995;95:213.
10 Kleijnen J, Knipschild P. Ginkgo biloba. Lancet 1992;340:1136-39.
10 Pronsky, Z Food Medication Interactions, 11th edition, 1999
10 Brinker, F Herb Contraindications and Drug Interactions, Eclectic Medical Publications, 1998
10 PDR for Herbal Medicines, 2nd edition, Medical Economics Company, 2000
11 Tyler, V.E.: The Honest Herbal. Haworth, Binghampton, NY, 1993.
11 Janetzky K, Morreale AP. Probable interaction between warfarin and ginseng. Am J Health-Syst Pharm 1997;54:692-93.
11 Yu CM, Chan JCN, Sanderson JE. Chinese herbs and warfarin potentiation by "danshen." J Intern Med 1997;241:337-39.
11 Tatro D, ed. Anticoagulants-quinine derivatives. In Drug Interaction Facts. St. Louis, MO: Facts and Comparisons, Jul 1993.
11 Harris JE. Interaction of dietary factors with oral anticoagulants: Review and application. J Am Diet Assoc 1995;95:580-84 [review].
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The information in Drug Watch is provided as a courtesy to NewsTarget readers by Applied Health Solutions in cooperation with Healthway Solutions. Although the information is presented with scientific references, we do not wish to imply that this represents a comprehensive list of considerations about any specific drug, herb or nutrient. Nor should this information be considered a substitute for the advice of your doctor, pharmacist, or other healthcare practitioner. Please read the disclaimer about the intentions and limitations of the information provided on these pages. It is important to tell your doctor and pharmacist about all other drugs and nutritional supplements that you are taking if they are recommending a new medication. Copyright © 2007 by Applied Health Solutions, Inc. All rights reserved.