Liu JF, Srivatsa A, Kaul V. Black licorice ingestion: Yet another confounding agent in patients with melena. World J Gastrointest Surg 2010; 2(1): 30-31 [PMID: 21160832 DOI: 10.4240/wjgs.v2.i1.30]
Corresponding Author of This Article
Arun Srivatsa, MD, Strong Memorial Hospital/University of Rochester, Medical Center, Division of Gastroenterology & Hepatology, Department of Internal Medicine, 601 Elmwood Avenue Box 646, Rochester, NY 14642, United States. arun_srivatsa@urmc.rochester.edu
Article-Type of This Article
Case Report
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World J Gastrointest Surg. Jan 27, 2010; 2(1): 30-31 Published online Jan 27, 2010. doi: 10.4240/wjgs.v2.i1.30
Black licorice ingestion: Yet another confounding agent in patients with melena
Judy Fong Liu, Arun Srivatsa, Vivek Kaul
Judy Fong Liu, Arun Srivatsa, Vivek Kaul, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, United States; Strong Memorial Hospital/University of Rochester, Medical Center, Division of Gastroenterology & Hepatology, Department of Internal Medicine, Rochester, NY 14642, United States
Author contributions: Liu JF researched the interaction between black licorice and warfarin, and was primarily involved in writing the initial manuscript; Srivatsa A was involved in the diagnosis and clinical care of the patient and contributed to the writing of the manuscript; Kaul V was involved in the diagnosis and clinical care of the patient and was involved in overseeing the final manuscript.
Correspondence to: Arun Srivatsa, MD, Strong Memorial Hospital/University of Rochester, Medical Center, Division of Gastroenterology & Hepatology, Department of Internal Medicine, 601 Elmwood Avenue Box 646, Rochester, NY 14642, United States. arun_srivatsa@urmc.rochester.edu
Telephone: +1-585-3304462 Fax: +1-585-2761911
Received: July 15, 2009 Revised: July 29, 2009 Accepted: August 6, 2009 Published online: January 27, 2010
Abstract
We describe an 80-year-old woman with atrial fibrillation, anti-coagulated with warfarin, who on two separate occasions developed black tarry stools and an elevated international normalized ratio (INR) after eating a pound of Black Licorice. During her most recent episode, her hematocrit was 14 (baseline 34) and her INR was 5.5 (baseline 2.1). She was advised to restrict licorice consumption, and a follow-up INR two weeks later was 1.2. Black Licorice is derived from the root of the plant, Glycyrrhiza glabra. The components of its extract inhibit the P450 system enzymes that metabolize Warfarin, inhibit thrombin, and prolong fibrinogen clotting times. Hence, the anti-thrombotic activity and inhibition of warfarin metabolism might synergistically amplify anti-coagulation. The presence of Black Licorice in the stool can also mimic melena and confound its clinical presentation. Health care providers should caution patients who are at risk for bleeding or on warfarin to avoid black licorice due to an elevated risk of gastrointestinal bleeding.
