Cinnamon Essential Oil: Side Effects on Skin
Powerful and fragrant, cinnamon essential oil also ranks among the most irritating in dermatology: here is the catalogue of skin and respiratory side effects actually documented.
Our article cinnamon essential oil: dangers and strong precautions already set the general framework of caution. This companion piece details the side effects actually documented in dermatology, drawing on the available clinical cases, for cinnamon essential oil.
What the reference study on contact dermatitis shows
A study by Ackermann, Aalto-Korte, Jolanki and Alanko, published in 2009 in Contact Dermatitis, documented cases of occupational allergic contact dermatitis, including via airborne exposure, in people regularly exposed to cardamom/">cinnamon at work (bakeries, pastry-making, perfumery) (see the study on Google Scholar). The compound most often responsible is cinnamaldehyde, the main aromatic constituent of nutmeg/">cinnamon bark, known for its strong sensitizing potential even at trace levels inhaled or through indirect contact. This finding is a reminder that prolonged diffusion in a closed room can be enough to sensitize a person, without any direct skin contact with the oil.
Catalogue of possible side effects
| Effect | Context | Frequency |
|---|---|---|
| Contact dermatitis (redness, burning) | Skin application, even diluted, in a sensitive person | Common for an undiluted essential oil |
| Allergic sensitization | Repeated exposure, including airborne diffusion | Documented in occupational settings |
| Irritation of the mucous membranes (nose, throat) | Overly concentrated or overly prolonged diffusion | Occasional |
| Chemical burn | Undiluted application | Rare but severe |
Cassia or Ceylon: a difference that matters for the skin
Cassia cinnamon (Cinnamomum cassia), the most common and cheapest kind, is noticeably richer in irritating compounds and coumarin than Ceylon cinnamon (Cinnamomum verum). This difference carries over into the essential oil: the Cassia version is generally considered more dermocaustic, which calls for even stricter dilution and extra vigilance when the botanical origin on the label is unclear.
Reducing the risk in practice
- Never apply undiluted to the skin, whatever the area;
- Dilute heavily (1% maximum, roughly one drop per tablespoon of carrier oil) before any occasional skin use;
- Inner-elbow patch test, 24 hours before first use, even diluted;
- Keep diffusion sessions short, in a ventilated room, to avoid prolonged airborne exposure;
- Stop immediately in case of redness, burning or breathing discomfort.
These pointers complement our article cinnamon essential oil: dangers and strong precautions. General precautions are gathered in our safety and precautions guide.
Your questions about cinnamon essential oil
Can cinnamon essential oil cause an allergy without direct skin contact?
Yes, a 2009 study documented cases of airborne allergic sensitization in people regularly exposed to cinnamon without direct skin contact, notably from prolonged diffusion.
Is Cassia cinnamon more irritating than Ceylon cinnamon?
Yes, Cassia cinnamon is generally richer in irritating compounds and coumarin, making it more dermocaustic as an essential oil. Dilution needs to be even stricter with this variety.
Can a diluted cinnamon essential oil still irritate the skin?
Yes, even diluted to 1%, a skin reaction remains possible in sensitive people. A prior inner-elbow patch test is recommended before any application, even diluted.
How long can cinnamon essential oil be diffused safely?
Short sessions, in a ventilated room, limit the risk of mucous-membrane irritation and airborne sensitization documented in prolonged occupational exposure.
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