Cinnamon Supplements May Reduce Effectiveness of Medications, Study Finds

Cinnamon is a beloved spice in kitchens around the world—but in supplement form, it may alter how quickly drugs are metabolized.

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That sprinkle of cinnamon in your coffee or oatmeal? Probably harmless. But taken as a supplement, it could change how your body processes prescription drugs, new research suggests.

Cinnamaldehyde, the compound behind cinnamon’s signature flavor and scent, can interfere with how the body processes medications. The recent study on human liver and gut cells found that at high concentrations, the compound may speed up drug metabolism, clearing medications before they can take full effect.

“Cinnamaldehyde has a low to moderate potential for drug interactions based upon our preliminary in vitro studies,” co-author of the study Bill Gurley, who is a principal scientist at the National Center for Natural Products Research, told The Epoch Times in an email.

What Researchers Discovered

In a study from the University of Mississippi, published in Food Chemistry: Molecular Sciences, researchers found that cinnamaldehyde can switch on certain receptors in the body—known as PXR and AhR—that may cause the body to clear medications too fast, which can cause them to reduce their effectiveness.

At concentrations above 270 micrograms per milliliter, which would be reached only through taking high-dose supplements, cinnamaldehyde activated these receptors, acting like gatekeepers, telling the body how quickly to break down and eliminate medications.

Researchers say that this could be a concern for people taking certain medications—particularly drugs metabolized by the liver enzymes CYP2C9 and CYP1A2, such as some blood thinners, diabetes drugs, antidepressants, and anti-inflammatory drugs.

“Cinnamon and cinnamon-based supplements are quite safe when used in moderation,” Gurley said. “The likelihood that cinnamaldehyde poses any risk for clinically relevant drug interactions is quite low.”

The researchers found no changes in PXR activity at lower levels of cinnamaldehyde (up to 20 micrograms per milliliter), suggesting that everyday use—like those typically used in cooking—is unlikely to be a problem.

Even in a clinical study where participants took a full teaspoon of cinnamon powder, cinnamaldehyde wasn’t detectable in the bloodstream—only its harmless breakdown products. That means moderate daily use of ground cinnamon—up to 1–2 grams a day, or about half to one teaspoon—isn’t a concern. So your morning chai or cinnamon muffin is just fine.

“It is okay to consume cinnamon in food or take it as a supplement in moderation,” Shabana Khan, a principal scientist at the university’s National Center for Natural Products Research and co-author of the study, told The Epoch Times in an email. Health concerns, however, can arise when supplements are used in high doses or for long periods—especially without a doctor’s knowledge.

Some people take cinnamon products as a dietary supplement for weight loss, blood sugar management, and reducing inflammation.

“It’s difficult to define how much is too much since different preparations or products / supplements will have different quantities or vary in composition,” she said. “It should be used in moderation.”

Know Your Cinnamon

Cinnamon is used in several forms, each with varying levels of risk.

Ground cinnamon, the kind you likely have in your spice rack, is used in cooking and baking, and up to a teaspoon is considered safe. Cinnamon oil, often used in foods and personal care products, poses little risk in small amounts. However, supplements, which can contain anywhere from 500 to 1,000 milligrams per dose, can be more concentrated and potentially interfere with medications when taken regularly.

Most cinnamon sold in U.S. stores is cassia cinnamon, which contains significantly higher levels of cinnamaldehyde than Ceylon cinnamon (or “true”) cinnamon.

Labels don’t always list the type of cinnamon used; unless otherwise stated, it’s mostly like going to be cassia. You can also contact the manufacturer for clarification, especially if you are taking cinnamon in supplement form.

Apart from cinnamaldehyde, cinnamon also contains coumarin, a naturally occurring blood thinner.

“Cassia cinnamon, often sourced from regions like Southern China, contains significantly higher levels of coumarin and is a potent blood thinner compared to true cinnamon (Cinnamomum verum) from Sri Lanka,” study co-author Amar Chittiboyina, associate director at the National Center for Natural Products Research, told The Epoch Times in an email.

True cinnamon or Ceylon cinnamon contains much less of the naturally occurring compound coumarin and is generally considered safer. High coumarin intake can increase the risk of bleeding when combined with blood-thinners.

“We strongly advise individuals currently taking blood thinners who are considering incorporating cinnamon into their daily routine to consult with their primary healthcare physician,” Chittiboyina said.

Still, researchers say that when used appropriately, cinnamon may offer benefits. A 2022 scientific review highlighted cinnamaldehyde’s potential anti-inflammatory, anti-diabetic, anti-bacterial, anti-fungal, and even anti-cancer properties—in lab studies.

But as with many natural compounds, the benefits may depend on the dose, the form, and how it’s used.

Other Competing Foods and Herbs

Cinnamon isn’t the only natural ingredient that can interact with medications. Common foods and herbs can affect how drugs are absorbed or broken down—something to keep in mind if you take medication regularly.

For example, grapefruit can block enzymes that break down certain drugs—such as some cholesterol-lowering statins—potentially raising the risk of side effects. Leafy greens are rich in vitamin K, which can interfere with blood thinners like warfarin. Dairy products can reduce the absorption of some antibiotics, making them less effective.

Several herbs and supplements have also been linked to well-documented drug interactions, according to Gurley. St. John’s Wort, often used for mild depression, can reduce the effectiveness of medications like antidepressants, birth control pills, and antivirals by speeding up liver enzyme activity.

Goldenseal may slow down drug metabolism of certain statins, antihistamines, and sedatives, increasing drug levels in the body. And licorice root—unless it’s had the glycyrrhizin compound removed—can raise blood pressure and interfere with blood pressure medications.

“Our best advice is to talk to a health care provider before using any supplements along with prescription medicine,” Khan said.