A sprinkle of cinnamon is a nice addition to many treats and drinks. While it is most commonly found in holiday goodies, a little bit of cinnamon is good any time of the year. Cinnamon is a product made from the inner portion of the cinnamon tree’s bark. The tree’s thin inner bark is surrounded by oil where, through processing, commercial quality cinnamon is made. The coumarin enzyme is said to have been found in some cinnamon products. This enzyme would normally be responsible for increasing the bleeding time in patients taking warfarin. Traditional use of small amounts of cinnamon, though, has not resulted in any changes of warnings or precautions for patients taking warfarin. However, new forms of cinnamon should be used with caution by warfarin patients.
Concerns have been raised with the use of cinnamon bark and warfarin together.1 Known for its rich and strong flavor, cinnamon bark and its oil is used for cooking and as an herbal supplement for a variety of ailments. Since oils tend to be more concentrated than traditional powder forms, use by a patient on warfarin can raise a cause for concern. Potential interactions between cinnamon bark and warfarin are labeled as “significant”, meaning that there is a higher chance of an interaction occurring.1 While cinnamon bark is far more common in causing drug interactions with diabetic medications, increased bruising and bleeding risk has been reported in patients taking warfarin and using cinnamon bark.1,2
Herbs and supplements are not strictly regulated by the U.S. Food and Drug Administration (FDA) and these products are not required to be tested for effectiveness, purity, or safety. In general, dietary supplements should only be taken under the supervision of your doctor and, just like with any new medication or herbal supplement, you should discuss uses of cinnamon, cinnamon bark or its extract with your healthcare provider to monitor the potential risk of elevated INR test results.