Cassia oil and cinnamon oil are not the same thing, though they’re closely related and frequently confused. They come from different species of the same plant genus, have different chemical profiles, and carry different safety considerations, particularly around a compound called coumarin. The confusion is made worse by labeling: in the U.S., the FDA allows both cassia and true cinnamon to be sold under the single label “cinnamon,” so many products don’t distinguish between them at all.
They Come From Different Trees
True cinnamon oil comes from Cinnamomum verum (also called Ceylon cinnamon), a tree native to Sri Lanka. Cassia oil comes from Cinnamomum cassia (Chinese cinnamon), grown primarily in China, Indonesia, and Vietnam. They’re in the same botanical family and share a similar spicy warmth, which is why they’ve been lumped together for centuries. But only Cinnamomum verum carries the designation “true cinnamon.”
A third species, Cinnamomum loureirii (Saigon cinnamon), also falls under the cassia umbrella. All three are legally sold as “cinnamon” in the United States. The FDA’s guidance document on spice definitions lists Ceylon cinnamon, Chinese cinnamon, and Saigon cinnamon interchangeably under the single heading “Cinnamon (Cassia).” This means the bottle of “cinnamon oil” in your cabinet is most likely cassia, since cassia is cheaper and far more widely produced.
How Their Chemistry Differs
Both oils get their characteristic spicy scent from cinnamaldehyde, but the concentrations and supporting compounds vary significantly. Cassia bark oil is roughly 76 to 78% cinnamaldehyde, making it intensely spicy and one-dimensional in flavor. Ceylon cinnamon bark oil also contains cinnamaldehyde, but in lower proportions, with a more complex mix of other aromatic compounds that give it a softer, more layered profile.
There’s another wrinkle worth knowing: Ceylon cinnamon leaf oil is a completely different product from Ceylon cinnamon bark oil. The leaf oil is dominated by eugenol (about 80%), the same compound that gives cloves their smell, and contains only around 16% cinnamaldehyde. If you buy “cinnamon oil” without checking whether it’s from bark or leaf, you could end up with something that smells more like cloves than cinnamon. Cassia oil, by contrast, is almost always derived from bark and consistently high in cinnamaldehyde.
The Coumarin Problem
The most important practical difference between these oils is coumarin, a naturally occurring compound that can damage the liver in high doses. Cassia cinnamon contains up to 1% coumarin. True Ceylon cinnamon contains roughly 0.004%, a negligible trace. In one study of 60 ground cinnamon samples from retail stores, coumarin levels ranged from 2,650 to 7,017 milligrams per kilogram. A sample sourced directly from a Ceylon cinnamon plantation in Sri Lanka had coumarin levels below the detection limit.
The European Food Safety Authority has set a tolerable daily intake for coumarin at 0.1 milligrams per kilogram of body weight. For a 150-pound person, that works out to about 6.8 milligrams per day. With cassia cinnamon containing coumarin concentrations in the thousands of milligrams per kilogram, even modest daily use of cassia products can approach or exceed that threshold. This matters most for people who use cinnamon supplements or add cinnamon oil to food or drinks regularly. Occasional use is unlikely to cause problems, but daily, heavy use of cassia oil specifically warrants attention.
Aroma and Appearance
If you open both bottles side by side, the difference is immediately obvious. Ceylon cinnamon bark oil smells warm, sweet, and subtly woody, with a complexity that unfolds gradually. Cassia oil hits harder: sharp, hot, intensely spicy, almost aggressive in its heat. Think of it as the difference between a nuanced spice blend and a single strong pepper.
Color provides another clue. Cassia oil tends to be yellow to reddish-brown. Ceylon cinnamon bark oil is typically pale yellow to amber, while Ceylon leaf oil runs pale yellow to light brown with a distinctly clove-like scent.
Health Benefits Are Similar, With Caveats
Both types of cinnamon show blood-sugar-lowering and anti-diabetic effects in research, and both have shown the ability to block the buildup of tau proteins associated with neurological decline. No head-to-head studies have compared the health benefits of Ceylon versus cassia cinnamon directly, so it’s not possible to say one is definitively more effective than the other.
The caveat is that most human studies on cinnamon’s health effects have used cassia, simply because it’s more common and cheaper. So while cassia has a stronger evidence base, that’s a product of availability, not proven superiority. If you’re choosing between the two for regular supplementation, the coumarin issue tips the balance toward Ceylon for long-term daily use.
How to Tell What You’re Actually Buying
Because U.S. labeling laws don’t require manufacturers to specify which species of cinnamon is in their product, you need to look beyond the front label. A bottle marked “cinnamon oil” with no further detail is almost certainly cassia. If you want true Ceylon cinnamon oil, look for products that explicitly state “Ceylon,” “Cinnamomum verum,” or “Cinnamomum zeylanicum” on the label. Reputable essential oil brands will list the Latin binomial on the bottle.
Price is another indicator. Ceylon cinnamon oil costs significantly more than cassia because the trees produce less oil and are grown in a narrower geographic range. If the price seems too good for a product claiming to be Ceylon, it probably is. You should also check whether the oil is from bark or leaf, since those are chemically distinct products with different uses, aromas, and properties.