Are there side effects to ceylon cinnamon? Understanding the risks

November 27, 2025 •

3 min read

While it is generally safe, ceylon cinnamon, unlike its Cassia counterpart, contains minimal amounts of coumarin. However, side effects can still occur, particularly with excessive intake. This article explores the potential risks associated with Ceylon cinnamon, ensuring safe usage.

Quick Summary

This guide details the potential risks of ceylon cinnamon consumption, highlighting its low coumarin content compared to Cassia. It covers potential allergic reactions, digestive issues, drug interactions, and discusses appropriate dosage for safe use.

Key Points

Low Coumarin Content: Ceylon cinnamon is significantly safer for regular consumption than Cassia cinnamon due to its very low coumarin levels, which can be hepatotoxic in high doses.
Allergic Reactions: Compounds like cinnamaldehyde may cause oral irritation, skin rashes, or, rarely, severe allergic responses.
Gastrointestinal Issues: High intake can lead to mild digestive discomfort, including nausea, heartburn, or stomach pain.
Drug Interactions: Ceylon cinnamon can interfere with medications for diabetes, blood pressure, and blood thinners, potentially amplifying their effects.
High-Risk Populations: Pregnant women, breastfeeding mothers, and individuals with liver disease should be cautious with high doses and supplements due to limited safety data.
Dosage Matters: To minimize risks, consume Ceylon cinnamon in moderate amounts, generally between 0.5 and 3 grams daily for a defined period, and avoid long-term, high-dose supplementation.

Ceylon vs. Cassia Cinnamon: The Crucial Difference in Side Effects

One of the most important factors when considering the side effects of cinnamon is the distinction between Ceylon cinnamon (Cinnamomum verum) and Cassia cinnamon (Cinnamomum cassia). Cassia cinnamon, commonly found in supermarkets, contains a high amount of coumarin. In contrast, Ceylon cinnamon, often referred to as "true cinnamon," contains only trace amounts of this compound.

The Role of Coumarin in Liver Health

Coumarin can be toxic to the liver when consumed in large, regular doses over a prolonged period. Sensitive individuals or those with pre-existing liver conditions are particularly vulnerable. The European Food Safety Authority (EFSA) and other health organizations have established a tolerable daily intake (TDI) for coumarin to prevent liver damage. Because of its extremely low coumarin content, Ceylon cinnamon is the safer choice for individuals who consume cinnamon frequently or in larger quantities.

Potential Allergic Reactions

Both types of cinnamon, including Ceylon, contain cinnamaldehyde, which can trigger allergic reactions in some people. Symptoms can range from mild to severe and may include:

Skin rashes or contact dermatitis upon topical application.
Oral stomatitis, characterized by mouth sores, pain, and inflammation, often from cinnamon-flavored products like gum or toothpaste.
More severe, systemic reactions like hives, wheezing, or difficulty breathing, although these are rare.

Gastrointestinal Discomfort

While generally mild, excessive intake of Ceylon cinnamon can irritate the gastrointestinal tract, leading to symptoms such as:

Nausea
Stomach ache or bloating
Heartburn
Constipation or diarrhea

Potential Drug Interactions and High-Risk Groups

Ceylon cinnamon can interact with certain medications, primarily due to its blood sugar-lowering and blood-thinning properties. It is essential to consult a healthcare professional before taking cinnamon supplements, especially if you fall into one of the following high-risk groups or take the medications listed below.

Comparison of Ceylon and Cassia Side Effects


Feature	Ceylon Cinnamon	Cassia Cinnamon (Common/Regular)
Coumarin Content	Very low, considered safe for regular use	High levels, potential liver toxicity with excessive intake
Hepatotoxicity Risk	Negligible for most at normal doses	Significant risk with long-term, high-dose consumption
Allergic Reactions	Possible, due to cinnamaldehyde	Possible, due to cinnamaldehyde
Blood Sugar Interaction	Can lower blood sugar, caution with diabetes meds	Can lower blood sugar, caution with diabetes meds
Blood Thinning Effects	Potential interaction with anticoagulant medications	More likely to interact due to coumarin content

Who Should Exercise Caution?

Individuals on Diabetes Medication: Ceylon cinnamon can mimic the effects of insulin, and taking it alongside antidiabetic drugs may cause blood sugar to drop too low (hypoglycemia).
Those on Blood Thinners: The anticoagulant properties of cinnamon, although more pronounced in Cassia, can theoretically interact with blood-thinning medications like warfarin, increasing the risk of bleeding.
Pregnant or Breastfeeding Women: While food amounts are considered safe, large doses or supplements are not recommended due to a lack of sufficient research and a theoretical risk of uterine contractions.
Individuals with Liver Disease: Even the trace coumarin in Ceylon cinnamon could be problematic for those with compromised liver function.
People with Pending Surgery: Cinnamon can interfere with blood sugar and blood pressure control. It is often recommended to stop taking cinnamon supplements at least two weeks before a scheduled surgery.

Understanding Dosage for Safety

For those consuming Ceylon cinnamon for its purported health benefits, such as blood sugar management or antioxidant effects, moderation is key. Studies on Ceylon cinnamon have used dosages ranging from 0.5 to 3 grams daily for up to six months without significant adverse effects. However, long-term safety data for larger amounts is not well established. It is always best to start with a small amount and observe your body's reaction. As with any supplement, buying from a reputable vendor is crucial to ensure product quality and purity.

Conclusion

While generally very safe, especially when compared to high-coumarin Cassia cinnamon, Ceylon cinnamon can have side effects if consumed in excessive amounts or by individuals with specific health conditions. The most common issues are mild gastrointestinal distress and allergic reactions. However, interactions with medications for diabetes, blood pressure, and liver conditions warrant caution. By understanding the difference between Ceylon and Cassia and moderating intake, most people can enjoy Ceylon cinnamon safely as a flavorful spice or supplement.

For more detailed information on coumarin and liver health, consult resources from the Bundesinstitut für Risikobewertung.

Frequently Asked Questions

Yes, moderate daily consumption of Ceylon cinnamon is generally considered safe for most healthy adults, especially in food quantities. Its low coumarin content makes it a safer option for frequent use compared to Cassia cinnamon.

The risk of liver damage from Ceylon cinnamon is very low. Unlike Cassia cinnamon, which contains high levels of coumarin, Ceylon has only trace amounts of the compound that can be hepatotoxic in large doses.

While cinnamon used in food is generally safe, large, medicinal quantities or supplements are not recommended during pregnancy or breastfeeding due to insufficient safety data and a theoretical risk of uterine contractions.

Yes, allergic reactions are possible, though rare. The compound cinnamaldehyde can cause symptoms like oral sores (stomatitis), skin rashes (contact dermatitis), or, in rare cases, more severe systemic reactions.

A safe daily amount for therapeutic purposes is typically between 0.5 and 3 grams for a limited duration. Long-term use of large doses has not been thoroughly studied.

Yes, there is a potential for interaction. Although Ceylon cinnamon has less of an effect than Cassia, its blood-thinning properties may increase the risk of bleeding for individuals on anticoagulant medications.

The main difference is the coumarin content. Cassia cinnamon contains high levels of coumarin, which can be harmful in large amounts, while Ceylon cinnamon has only minimal levels, making it the safer choice for regular, high-dose consumption.