Warfarin interaction with <em>Matricaria chamomilla</em>
Abstract
No cases have been reported of Matricaria chamomilla potentiating the effects of warfarin. Nevertheless there is a theoretical risk for potentiation, since the herb is thought to be a coumarin constituent. We describe the case of a 70-year-old woman who, while being treated with warfarin, was admitted to hospital with multiple internal hemorrhages after having used chamomile products (tea and body lotion) to soothe upper respiratory tract symptoms. Patient education on the potential risk of taking chamomile products while being treated with warfarin is necessary to avoid such occurrences.
Acknowledgments
We thank Drs. Mark A. Rabinovitch and Danielle Libersan from the Division of Cardiology, Montreal General Hospital and McGill University Health Centre, for their respective expertise in cardiology and pharmacology.
Footnotes
Editor's take
• Warfarin, itself derived originally from sweet clover, has anticoagulant properties that resemble those of the coumarin family of substances. No surprise, then, that it may act synergistically with other plant materials that contain coumarins.
Implications for practice: The list of pharmaceuticals that interact is long, and the list of herbal foods and medicines is lengthening. Chamomile's propensity to cause anticoagulation has been known, but no instance of interaction been reported. This case report implies that chamomile should be added to the list of substances that may interact with warfarin.
Contributors: All authors took part in the drafting and critical revision of the article and have approved the final version to be published.
Competing interests: None declared.
Correspondence to:Dr. Louise Pilote, Divisions of General Internal Medicine and Clinical Epidemiology, Montreal General Hospital, 1650 Cedar Ave., Rm. L10-421, Montréal QC H3G 1A4; fax 514 934-8293;ac.lligcm@etolip.esiuol
REFERENCES
References
- 1. Wells P, Holbrook AInteractions with drugs and food. Ann Intern Med 1994;121:676-83. [[PubMed]
- 2. Heck A, DeWitt B, Lukes APotential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000;57:1221-30. [[PubMed]
- 3. O'Hara M, Kieker D, Farrell K, et alA review of 12 commonly used medicinal herbs. Arch Fam Med 1998;7(6):523-36. [[PubMed]
- 4. McKesson Health Solutions LLC. Chamomile natural remedy [patient handout]. St. Louis: MD Consult [Elsevier]; 2003.
- 5. Newall C, Anderson L, Phillipson J. A guide for health-care professionals, herbal medicines. London (UK): Pharmaceutical Press; 1996. p. 132.
- 6. Ganzera M, Schneider P, Stuppner HInhibitory effects of the essential oil chamomile (Matricaria recutita L.) and its major constituents on human cytochrome P450 enzymes. Life Sci 2006;78(8):856-61 (Epub 2005 Aug 31). [[PubMed]
- 7. Kaminsky LS, Zhang Z-YHuman P450 metabolism of warfarin. Pharmacol Ther 1997;73:67-74. [[PubMed]