Warfarin, sold under the brand name Coumadin, is a blood thinner that doctors prescribe to reduce the risk of blood clots, heart attack and stroke. If you take warfarin, you need to carefully control your diet, as a number of foods and beverages can interfere with the blood-thinning action of the drug. Cranberry juice is one beverage you should consume only in limited amounts.
Cranberry Juice Interaction
Some people drink cranberry juice regularly to limit their risk for urinary tract infections. However, cranberry juice may interact with warfarin and cause the drug to stay in the body longer than normal, building up to higher levels and potentially causing dangerous side effects. These include hemorrhage, swelling, unexplained bruising, vomiting, nausea, numbness, diarrhea and difficulty moving.
Potential Cause
The potential cause for the interaction between warfarin and cranberry juice is the high level of antioxidants called flavonoids contained in cranberry juice. Flavonoids may inhibit the function of the enzymes that break down warfarin in the body. However, the evidence for this interaction is mainly based on case studies rather than clinical studies, so further research is needed to confirm this interaction.
Safe Consumption
In clinical studies, doses of 8 oz. of cranberry juice per day did not cause a measurable interaction with warfarin, according to an article published in "Pharmacy Times" in June 2010. Likewise, doses of 1,000 mg of cranberry extract tablets taken three times per day appear safe. However, speak with your doctor before consuming cranberry juice or cranberry extract tablets to verify that they are safe for you.
Considerations
If you like to consume large amounts of cranberry juice, your doctor may be able to put you on a different medication that does not have a potential interaction with cranberry juice. Otherwise, it is best to play it safe and limit or avoid cranberry juice in your diet, as different people react differently to medications.
References
- "Pharmacy Times"; Drug Interactions: Cranberry Juice and Warfarin: What Have We Learned?; John R. Horn, et al.; June 2010
- "British Medical Journal"; Possible Interaction Between Warfarin and Cranberry Juice; Rafe Suvarna, et al.; December 2003
- BBC News; Cranberry Juice Clot Drug Warning; September 2003
- MedlinePlus: Cranberry
- MayoClinic.com; Warfarin Side Effects: Watch for Dangerous Interactions; January 2010
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