Cinnamon can be harmful when combined with prescription drugs, study finds

Cinnamon has long flavored meals, teas, and baked goods. It also shows up in traditional remedies to ease everything from inflammation to high blood sugar. But new research finds that taking too much of it—especially in concentrated supplement form—could do more harm than good, particularly when combined with prescription drugs.

A recent study highlights how a key chemical in cinnamon may affect how your body handles medication. Researchers from the University of Mississippi discovered that cinnamaldehyde, the main active compound in cinnamon, may interfere with how your body processes drugs. That could reduce the medicine’s effect and even pose risks for people with chronic illnesses.

Cinnamaldehyde gives cinnamon its familiar flavor and scent. But in your body, it doesn’t just sit quietly. Researchers found that cinnamaldehyde shows 100% bioaccessibility. That means the body can fully absorb it, whether taken on an empty stomach or with food. Once inside, enzymes in the liver quickly convert cinnamaldehyde into cinnamic acid. This process happens whether the cinnamaldehyde comes from cinnamon oil or cinnamon bark.

The liver plays a key role here. It breaks down many foreign substances—called xenobiotics—including drugs, herbs, and food compounds. The study tested cinnamaldehyde using human liver microsomes and liver S-9 fractions. These are systems that mimic how the liver processes chemicals. Both showed that cinnamaldehyde quickly changes into cinnamic acid through oxidation.

This transformation is important because it affects how long the compound stays active in the body and what effects it may cause. Cinnamaldehyde’s interaction with drug-processing systems could impact how well medications work.

Your body uses special protein receptors to control how quickly it clears drugs. Two of these—PXR (pregnane X receptor) and AhR (aryl hydrocarbon receptor)—help regulate drug-metabolizing enzymes. These enzymes can speed up or slow down the breakdown of medicines, which may change their effects.

In lab studies, cinnamon oil activated AhR in a dose-dependent way. That means the more cinnamon oil cells were exposed to, the more the AhR responded. However, pure cinnamaldehyde and cinnamic acid didn’t trigger this same reaction. Meanwhile, both cinnamon oil and cinnamic acid activated PXR in liver and intestinal cells.

Why does that matter? Activating PXR can increase the breakdown of medications. This means drugs may leave the body faster than expected, reducing how long or how well they work. In some cases, that could mean the drug no longer works at all.

Dr. Shabana Khan, a lead scientist on the study, explained the concern clearly: “Health concerns could arise if excessive amounts of supplements are consumed without the knowledge of health care provider or prescriber of the medications.” She warned that this could lead to a “rapid clearance of the prescription medicine from the body,” which may cause it to become less effective.

The study also found that cinnamon oil and cinnamaldehyde interfere with two major liver enzymes—CYP2C9 and CYP1A2. These enzymes help the body break down many common drugs, including ones used for blood pressure, mood disorders, and cancer treatment.

If these enzymes are slowed or blocked, drug levels in the blood may build up to unsafe levels. On the other hand, if the enzymes are sped up, drug levels may drop too quickly. Either effect could lead to treatment failure or dangerous side effects. That’s why these findings are especially important for people who take medications regularly.

Cinnamon comes in different forms. What you find in a spice jar at the store is usually ground bark from Cassia cinnamon, which is cheaper and more common. But Cassia also contains high levels of coumarin, a chemical known to thin the blood. “Coumarin's anticoagulant properties can be hazardous for individuals on blood thinners,” said Dr. Amar Chittiboyina, an expert from the same research center.

In contrast, the type called Ceylon cinnamon, sometimes known as “true” cinnamon and usually grown in Sri Lanka, contains much less coumarin. That makes it a safer choice for people at risk of bleeding problems.

Cinnamon oil is another story. Often used in food flavoring, skin treatments, and natural remedies, it shows less risk for herb-drug interactions. That’s because it has a different makeup than cinnamon bark and contains less coumarin overall. Still, the potential for harm rises when people consume cinnamon in large amounts—especially in supplement form, where concentrations are much higher than those used in food.

Cinnamon has long had a place in natural medicine. Many people use it to manage blood sugar or inflammation. But experts caution that natural doesn’t always mean safe.

“Despite its vast uses, very few reports were available to describe the fate of its major component—cinnamaldehyde,” said Dr. Khan. She explained that understanding how this chemical behaves inside the body was key to learning how cinnamon might affect drug actions. Clinical studies in people are still needed to know the full risks. But the lab data already show that cinnamaldehyde can activate receptors that help clear drugs from the system.

“We know there’s a potential for cinnamaldehyde to activate these receptors that can pose a risk for drug interactions,” said Dr. Bill Gurley, a co-author of the study. “That’s what could happen, but we won’t know exactly what will happen until we do a clinical study.” Until those studies are done, the safest path is to be cautious.

People dealing with long-term health problems should pay special attention to these findings. “People who suffer from chronic diseases... should be cautious when using cinnamon or any other supplements,” said Dr. Khan. “Our best advice is to talk to a health care provider before using any supplements along with the prescription medicine.” The study makes it clear that supplements do not replace proper medical treatment.

That doesn’t mean cinnamon has no benefits. Adding a sprinkle of cinnamon to your oatmeal or tea won’t likely cause harm. But if you’re thinking about taking it as a capsule or oil, talk to your doctor first—especially if you’re already on medication. Cinnamon may be natural, but its effects on your body and medicine aren’t always simple or harmless.

Research findings are available online in the journal Food Chemistry: Molecular Sciences.

Note: The article above provided above by The Brighter Side of News.

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