A Comprehensive Review of Potential Warfarin-Fruit Interactions

Abstract

Purpose: The aim of this review is to discuss possible interactions that may occur between warfarin and fruit products. Methods: A literature search was conducted using the search terms: “warfarin (Coumadin®) and fruit interactions, warfarin and fruit, warfarin and fruit juice, case reports and clinical trials”. Results: A total of 23 citations (15 case reports and 7 controlled clinical trials) were reviewed. The majority of cases involved cranberry products, while pomegranate juice, avocado, grapefruit juice, mango, and papain were also implicated in reports of suspected warfarin-fruit interactions. Cranberry juice was also the most frequently studied fruit product. Other fruit products evaluated with warfarin in controlled clinical trials were cranberry concentrate and grapefruit juice. Conclusion: Although a number of case reports have been published that suggest warfarin has the potential to interact with several fruit products, it is difficult to determine their relevance, as scientific evidence is scarce. Until further information is available, clinicians may want to encourage patients to consume cranberry products and grapefruit juice in small to moderate quantities and to inquire about the recent consumption of mangos, pomegranate juice, and avocados when taking a dietary history or when assessing possible causes for international normalized ratio (INR) instability.