Warfarin Institute of America
DEDICATED TO YOUR HEALTH SINCE 2000
Black Cohosh Interaction with Warfarin (Coumadin, Jantoven)
by
Daniel Bates, Pharm D Candidate
University of Colorado Health Sciences Center School of Pharmacy
Black Cohosh is commonly used for symptoms of menopause like hot flashes.1,3 According to two reputable sources warfarin and black cohosh do not interact in a clinically significant manor. 1,3 There is one study that has shown invitro or experiments that have not been conducted in humans that a substrate of black cohosh inhibits the one of the two enzymes that breaks down warfarin called cytochrome p450 3A4.2 The reduction of this enzyme is only affected in the intestinal epithelium, not the major source of this enzyme, which is in the liver.2 Also to note the enzyme that is reduced by the substrate of black cohosh is the minor enzyme of the two enzymes that break down warfarin.2
Black Cohosh has also been use to treat some forms of migraines and osteoporosis.1 As for menopausal symptoms though most patients need to be treated for at least 4 to 12 weeks with black cohosh before there is a significant improvement in symptoms.1,3
Although there is a questionable drug interaction with black cohosh and warfarin, there is a possible disease interaction with black cohosh and Protein S Deficiency.3 Patients who have Protein S Deficiency and take black cohosh have an increased risk of thrombosis.3 In one case report a patient with systemic lupus erythematous and Protein S Deficiency started a product that contained black cohosh, red clover, dong quai, and wild yam.3 After taking this product for three days this patient developed a retinal vein thrombosis.3
In conclusion, black cohosh probably does not interact with warfarin in a clinically significant manor, but cation maybe exercised when monitoring ones INR with the start and stop of black cohosh especially for patients who metabolize warfarin slowly and do not require a large amount of warfarin to stay in their INR range. More well controlled studies need to be conducted to truly determine the effectiveness and time to start seeing improvements in menopausal symptoms, but from the data that is available most patients should see improvement in menopausal symptoms like hot flashes in as little as 4 weeks. In the case of patients with Protein S Deficiency extreme care should be taken if considering taking black cohosh due to an increased risk of thrombosis. In the case of this patient I would not recommend black cohosh due to the increased risk of thrombosis even though there is only case report documenting this, the risk is most likely outweighs the benefit of taking this product. As with any medication change, addition, or discontinuation while taking warfarin consult with your healthcare provider managing your warfarin as soon as possible to avoid serious drug interactions.
References:
1. Micromedex® Healthcare Series, (electronic version). Thomson Micromedex, Greenwood Village, Colorado, USA. Available at: http://0-www.thomsonhc.com.library.uchsc.edu:80 (expires 08/2006).
2. Burdette JE, Liu J, Chen SN, et al. Black cohosh acts as a mixed competitive ligand and partial agonist of the serotonin receptor. J Agric Food Chem 2003;51:5661-70.
3. Black Cohosh. Natural Medicines Comprehensive Database. Available at: www.naturaldatabase.com. Accessed Aug. 9, 2006.
©2006 Daniel Bates Used by Permission
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Last updated August 17, 2006
