Cinnamon could interact with some prescription medications, according to a new study

CNN

08-05-2025

While cinnamon is a popular spice used added to many foods, it has a long history of uses in traditional medicine in many cultures. Today, cinnamon products are sold as dietary supplements to help with a variety of healthy conditions, including treating diabetes, promoting weight loss and relieving hay fever and other inflammatory conditions.
But how much is too much cinnamon? Could there be negative impacts from overconsumption of cinnamon products? People should be cautious because cinnamon could affect the metabolism of prescription drugs, according to a study published in the journal Food Chemistry: Molecular Sciences. The authors warned against overconsumption of cinnamon-containing substances, especially in individuals with other health conditions.
To help us make sense of the study findings and what the major takeaways are for cinnamon consumption, I spoke with CNN wellness expert Dr. Leana Wen, an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore's health commissioner.
CNN: What is cinnamon — where does it come from and what are its potentially beneficial health effects?
Dr. Leana Wen: Cinnamon is a spice that comes the dried bark of Cinnamomum trees. The most common type of cinnamon sold in North America is Cassia cinnamon from the Cinnamomum aromaticum trees, according to the National Center for Complementary and Integrative Health, which is one of the centers under the National Institutes of Health. Ceylon cinnamon, sometimes called 'true' cinnamon, is from Cinnamomum verum trees.
Though some studies have suggested that cinnamon supplementation could be helpful for diabetes treatment or for weight loss, more research is needed to investigate the benefits.
Similarly, though preliminary research points to a possible role of nasal spray with Ceylon cinnamon as helping with allergic rhinitis, more research is needed to confirm that it could be a treatment.
The National Center for Complementary and Integrative Health states that 'research doesn't clearly support using cinnamon for any health condition.' Cinnamon is not approved by the US Food and Drug Administration for the treatment of any medical condition.
CNN: What is already known about possible risks of cinnamon consumption?
Wen: Cassia cinnamon may contain high levels of coumarin, which is a blood thinner. Ceylon cinnamon may also have trace amounts of coumarin. If someone who is already on anticoagulant medications ingests a large amount of coumarin, this could increase their bleeding risk.
In addition, there are known interactions between coumarin and the liver. Prolonged use of cinnamon products that have high coumarin content could pose health risks for people with liver disease. Moreover, the National Center for Complementary and Integrative Health states there are 'theoretical reasons' to think that there may be interactions between cinnamon and anticancer medications and nicotine.
CNN: What did this new study examine?
Wen: This new study examined the primary active ingredient of cinnamon, which is called cinnamaldehyde. Researchers first looked at whether cinnamaldehyde is well absorbed when orally ingested by examining gastric and intestinal fluids. They found that it is 100% bioaccessible in both fluids that are fasted and fed. That means that whether someone is fasting or has just eaten, cinnamaldehyde is expected to be well absorbed. They then discovered that cinnamaldehyde is rapidly metabolized into another compound, cinnamic acid, and that it can activate multiple receptors that affect drug metabolism.
The possible interference with drug metabolism is what led the authors to conclude that overconsumption could induce herb-drug interactions. They urge additional research looking into these possible interactions. Until those studies are complete, as the researchers indicated in an associated news release, they recommend that people looking to take cinnamon as a dietary supplement exercise caution and consult a physician before using.
CNN: Which people should use caution?
Wen: According to the study's researchers, the list of chronic conditions that should prompt caution before trying cinnamon supplementation includes hypertension, diabetes, cancer, arthritis, asthma, obesity, HIV/AIDS and depression.
I would add to that list anyone using blood thinner medications — for example, someone who has a history of heart disease and stroke, any medications that are cleared through the liver, and other dietary supplements that may interact with cinnamon, including turmeric, ginseng and gingko biloba.
CNN: What about sprinkling cinnamon in coffee or on pancakes? Should we be worried?
Wen: The researchers are quite clear that a sprinkling of cinnamon for typical culinary use is unlikely to cause problems. What they warn against is what they refer to as 'overconsumption.' This isn't clearly defined, as their study was not set up to examine what could be too high of a level of cinnamon. What overconsumption probably refers to is using concentrated cinnamon products like cinnamon supplements over a prolonged period — for instance, taking cinnamon capsules every day for months.
Individuals who are thinking of taking cinnamon supplements should be sure to consult their health care providers to check for possible medication interactions. They should also be aware that there's no clear evidence for the benefit of cinnamon supplementation.
CNN: What else would you like for people to know before starting dietary supplements?
Wen: Consumers should know that the FDA does not regulate dietary supplements like they do prescription medications. Under current law, the FDA does not have the authority to regulate the efficacy of dietary supplements. The FDA also does not review supplements before they go to market. Instead, the agency relies on post-market surveillance to identify safety problems.
People should be cautious about taking dietary supplements. Just because something is marketed as being 'natural' doesn't mean that it is safe. Also, something that is safe in small quantities may become unsafe in large quantities. People should always mention what supplements they are taking or thinking of taking to their health care provider to assess for drug interactions.