Worth a closer look
Evidence key Strong Moderate Weak How we grade
Labeled fragrance allergen (EU) Skin allergen Scent ingredient Limited by IFRA
- What it can be used for
- Adds flavor, adds scent, and makes alcohol undrinkable (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
- CAS number
- 104-55-2
Why it’s flagged
A fragrance allergen the EU requires companies to name on the label.
- Annex III entry 76. Source: EU Cosmetics Regulation, Annex III (restricted)
Must be named on EU labels above 0.001% in leave-on and 0.01% in rinse-off products. Elsewhere, including the US, it can hide inside “fragrance”.
Classified as a skin sensitizer (may cause an allergic skin reaction).
- Skin Sens. 1A (H317). Source: EU CLP Regulation, Annex VI harmonized classification
EU hazard statement H317: may cause an allergic skin reaction.
Used to add scent: its official function is perfuming or fragrance.
- Listed functions: denaturant, flavoring, perfuming. Source: EU CosIng ingredient database
The EU ingredient database (CosIng) lists this ingredient's function as perfuming or fragrance, so it may be there to add scent, even on a label that never says “fragrance.”
Use limited by the fragrance industry's own IFRA standard.
- IFRA standard “Cinnamic aldehyde”: use limited. Source: IFRA Standards Library
IFRA, the fragrance industry's own standards body, sets maximum amounts for this material in different kinds of products.
What the research says
- The independent dermatologists who ran this study concluded deodorants should contain cinnamal at less than 0.01% to protect people already sensitized, a stricter limit than the fragrance industry's later 0.05% IFRA standard. Strong evidence. Bruze et al. 2003
- Even the fragrance industry's own safety institute classes the cinnamon-scent chemicals cinnamal and cinnamyl alcohol as human skin sensitizers: in its volunteer tests, 29 of 451 people became allergic to cinnamal at 1% or more. Strong evidence. RIFM Expert Panel 2005 Industry-funded
- In a double-blind study, deodorants containing as little as 0.01% cinnamic aldehyde (cinnamal) triggered allergic skin reactions within weeks in people already allergic to it, while an identical unscented deodorant on the other armpit, and the same deodorants used by 20 non-allergic people, caused no reactions. Strong evidence. Bruze et al. 2003
- In people already allergic to cinnamal, a deodorant with just 0.01% of it triggered a reaction in 1 of 9, and 0.032% in 4 of 9; the industry limit is 0.05%, and it was set to prevent new allergies, not reactions in people already sensitized. Strong evidence. RIFM Expert Panel 2005 (citing Bruze 2003) Industry-funded
- The fragrance allergens found most in scented tampons were α-isomethyl ionone (in every tampon, 12.6-19.1 µg/g) and hexyl cinnamal, not the familiar citrus and lavender terpenes. Moderate evidence. Desmedt 2020
- Skin converts part of cinnamyl alcohol into cinnamal, the stronger allergen: on human skin samples, about 4% of applied cinnamyl alcohol became cinnamal within a day. Moderate evidence. RIFM Expert Panel 2005 Industry-funded
- Sanitary pads, panty liners and tampons can contain undisclosed fragrance allergens — chiefly alpha-isomethyl ionone (in every scented tampon tested), hexyl cinnamal, and benzyl salicylate, plus trace limonene, linalool, and geraniol — and in the EU they do not have to declare any of them. Moderate evidence. Pastor-Nieto 2021 (Desmedt 2020)
- Sensitivity to cinnamal varies enormously between allergic people: this study measured a 1000-fold range in the concentration needed to trigger a reaction. Moderate evidence. Bruze et al. 2003
About ingredients flagged like this one:
- In a survey of 187 US pediatric personal-care products, preservatives (57.8% of products) were a more common source of contact allergens than fragrance (29.4%), even though the products were being screened specifically for hypoallergenic/fragrance-related marketing claims. Moderate evidence. Hamann 2015
Each finding shows its evidence grade. See every graded fact or how we grade.
Don’t want it on you or in your air? Look for “fragrance-free,” not “unscented.” An unscented product can still contain a masking fragrance. Why the words matter.
What this page can’t tell you
These lists describe what a substance can do, its hazard. The risk from one product depends on how much is in it and how you use it, and the label doesn’t say how much.
Not being on a list doesn’t make an ingredient safe. It may never have been assessed.
“Fragrance” or “parfum” on a label can hide this ingredient and many others. In the US, the individual chemicals in a fragrance are rarely named on the label.
Check your products
Check a whole labelProducts that list itEWG Skin DeepShop fragrance-free
“Products that list it” opens Open Beauty Facts, a free database anyone can edit.
Flagged the same way
Official lists checked September 2026. Spotted a mistake? Tell us.