Warfarin-Cranberry Juice Interaction

Abstract

Our case report describes INR elevations in a patient previously stable on warfarin after ingestion of cranberry juice cocktail daily for several days. This elevation occurred on 2 separate occasions, which distinguishes our case from other published literature.

Herbal drugs and drug interactions

“…garlic, mistletoe, Essiac, Lingzhi, and astragalus) are used by cancer patients for treating the cancer and/or reducing the toxicities of chemotherapeutic drugs. Although some herbal medicines have shown potentially beneficial effects on cancer progression and may ameliorate chemotherapy-induced toxicities, it should be remembered that there is no or weak scientific basis for the clinical use of these herbal medicines in cancer management and almost none of these plant medicines have been tested in rigorous clinical trials (129,130). Further studies are warranted to investigate the efficacy and safety profiles of herbal medicines commonly used by cancer patients (34,51).…”

“…Cranberry juice is not marketed in Turkey, but dry fruit is consumed as a snack. There is an interesting case report about the interaction of warfarin with cranberry juice (129). A patient who was on warfarin therapy experienced an increase in INR on 2 different occasions after consuming cranberry juice for a few days.…”

Providing accurate information to patients who develop deep vein thrombosis

“…18 Interestingly, a study involving 10 volunteers who drank 240 ml of cranberry juice twice daily for 1 week did not identify an effect on the pharmacodynamics of warfarin, while a recent case report described a case in which INR increased to 4.6 in a woman who drank about 1,420 ml of cranberry juice cocktail daily for 2 days. 19,20 In summary, any foodstuff in reasonable amounts is unlikely to cause fluctuations in INR in those receiving warfarin.…”

Complementary and alternative medicine: Herbals and supplements: A review for the primary care physician

“…Polyphenol components of cranberry juice have significant antioxidant properties and cardiovascular health benefits [64]. Cranberry juice interacts with warfarin to increase the INR and potentiate the drug effect [65]. …”