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Cassia, commonly called Chinese cinnamon, is the thick-barked cinnamon widely sold in North America and used throughout Asian cooking and traditional medicine. Botanical naming is unusually confusing. Kew Plants of the World Online currently accepts Cinnamomum aromaticum Nees for the Chinese cassia species, while traditional medicine references, pharmacopoeias, clinical papers, and commerce often continue to use Cinnamomum cassia. Both names are included here so readers can recognize the same herbal tradition across older and newer sources.
Botanical Identity & Naming
Accepted name used here: Cinnamomum aromaticum Nees
Widely used medicinal/trade name: Cinnamomum cassia
Family: Lauraceae
Primary part used: bark; twigs are also important in Chinese herbal tradition.
A 2018 review by authors affiliated with the U.S. Pharmacopeia, Health Canada, and Traditional Medicinals specifically described cinnamon and cassia nomenclature as a challenge because different Cinnamomum species are often labeled simply “cinnamon.” That matters because chemistry, coumarin content, clinical evidence, and safety are not automatically transferable from one species to another.
Cassia vs. Ceylon “True” Cinnamon
Roosters Peacock treats cassia separately from Ceylon cinnamon (Cinnamomum verum). Cassia bark is usually thicker, harder, darker, and stronger tasting. A cassia stick commonly forms one thick curled layer, while Ceylon cinnamon is typically made of many thin papery layers rolled together.
The safety distinction that receives the most attention is coumarin. Cassia-type cinnamons generally contain much more coumarin than Ceylon cinnamon. Coumarin can cause reversible liver injury in susceptible people when exposure is high enough.
Culinary Use
Cassia is the familiar warm, sweet-hot spice used in baked goods, spice blends, curries, stews, beverages, confections, and savory dishes. Ground “cinnamon” sold in the United States is often cassia or another cassia-type cinnamon unless the package specifically identifies Ceylon cinnamon.
Chinese Herbal Tradition
Chinese herbal practice distinguishes different parts and preparations of the cinnamon tree. Rou Gui commonly refers to Chinese cinnamon bark, while Gui Zhi refers to cinnamon twig. Their traditional uses and formula roles are not identical even when they come from the same species. Bark and twig have long histories in decoctions and multi-herb formulas. Those traditional categories should be preserved as Chinese medicine concepts rather than flattened into one generic claim that “cinnamon treats” a disease.
Traditional Preparation
Cassia bark has historically been used as a culinary spice, powdered bark, infusion, decoction, and ingredient in compound herbal formulas. Twigs are also decocted in Chinese formulas. Whole-bark household preparations are different from concentrated extracts or essential oil.
Cinnamon essential oil is not equivalent to cinnamon tea or powdered bark. Essential oils concentrate volatile constituents such as cinnamaldehyde and can irritate or burn skin and mucous membranes when improperly used.
Constituents
Cassia contains cinnamaldehyde and other volatile compounds, polyphenols, procyanidins, and coumarin. Chemical composition varies by species, growing location, bark quality, storage, processing, and extraction method.
Blood Sugar & Metabolic Research
Cinnamon products have been studied extensively for blood glucose, insulin resistance, lipids, and metabolic health, but interpretation is complicated because many studies do not adequately identify which cinnamon species was used. NCCIH notes that research has not clearly supported using cinnamon to manage any health condition and that study results are difficult to compare because products differ.
Some trials and meta-analyses report changes in fasting glucose or other metabolic measurements, while others do not. These findings do not establish cassia as a replacement for diabetes medicines, dietary management, or monitoring.
Coumarin & Liver Safety
The German Federal Institute for Risk Assessment (BfR) emphasizes that cassia cinnamon can contain relatively high coumarin levels. BfR uses a tolerable daily intake of 0.1 mg coumarin per kilogram of body weight per day for long-term exposure. Actual coumarin content varies greatly from product to product, so a spoonful of one cassia powder may not match another.
Ordinary occasional culinary use is different from taking large daily spoonfuls or concentrated cinnamon supplements for months. People with liver disease or a history of liver injury should be particularly cautious with high, repeated cassia intake.
Safety & Interactions
- Liver: prolonged high cassia exposure may provide substantial coumarin. Susceptible individuals can develop liver injury.
- Blood sugar: concentrated cinnamon products may add to glucose-lowering medicines in some people.
- Skin and mouth: cinnamon, especially concentrated oil or flavoring, can cause irritation, allergic contact reactions, or oral burning.
- Medication review: people using medicines that affect the liver or blood glucose should distinguish ordinary spice use from medicinal-dose supplementation.
Pregnancy, Breastfeeding & Children
NCCIH considers cinnamon generally safe in amounts commonly used in foods during pregnancy, while information on larger medicinal amounts is limited. The same distinction applies during breastfeeding and in children: normal culinary exposure is not the same as concentrated supplements or essential oil.
Quality & Label Reading
Look for a botanical species on the label. “Cinnamon” alone does not tell you whether a product contains C. verum, Chinese cassia, Indonesian cassia, Vietnamese/Saigon cinnamon, or a blend. For long-term medicinal use, species identification and coumarin testing matter far more than they do when cinnamon is used occasionally as a kitchen spice.
Related Roosters Peacock Herb Guides
Ceylon Cinnamon / True Cinnamon (Cinnamomum verum)
Clove (Syzygium aromaticum)
Ginger (Zingiber officinale)
References
- Kew Science, Plants of the World Online — Cinnamomum aromaticum Nees.
- National Center for Complementary and Integrative Health — Cinnamon: Usefulness and Safety.
- Memorial Sloan Kettering Cancer Center — Cinnamon.
- German Federal Institute for Risk Assessment — FAQ on Coumarin in Cinnamon and Other Foods.
- Oketch-Rabah HA, Marles RJ, Brinckmann JA. Cinnamon and Cassia Nomenclature Confusion: A Challenge to the Applicability of Clinical Data.
- Zhang C, et al. Cinnamomum cassia Presl: Traditional Uses, Phytochemistry, Pharmacology and Toxicology.
- Liu S, et al. Review of the botany, ethnopharmacology, phytochemistry and pharmacology of Cinnamomi Cortex.
Last reviewed: September 26, 2026.
Roosters Peacock educational herb reference. Botanical naming is shown transparently because current taxonomic databases and medicinal literature do not use cassia nomenclature consistently.