Red flag
Evidence key Strong Moderate Weak How we grade
Banned in EU cosmetics Labeled fragrance allergen (EU) Skin allergen Scent ingredient Limited by IFRA
- Also on labels as
- HICC, Lyral
- What it can be used for
- Adds scent (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
- CAS number
- 31906-04-4, 51414-25-6
Why it’s flagged
Prohibited in cosmetics in the EU.
- Annex II entry 1380. Source: EU Cosmetics Regulation, Annex II (prohibited)
Annex II of the EU Cosmetics Regulation lists substances that must not be used in cosmetics sold in the EU.
A fragrance allergen the EU requires companies to name on the label.
- Annex II: now banned in EU cosmetics. 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: fragrance, 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 “3 and 4-(4-Hydroxy-4-methylpentyl)-3-cyclohexene-1-carboxaldehyde (HMPCC)”: 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
- People with chronic, treatment-resistant hand eczema and a history of reacting to scented products can ask their dermatologist for patch testing beyond the standard fragrance mix, including citral, Lyral, hydroxycitronellal and oxidized limonene/linalool. Moderate evidence. Heydorn 2003 Industry-funded
About ingredients flagged like this one:
- The EU bans more than 1,400 substances from cosmetics, while US rules restrict only a handful. Moderate evidence. Alblooshi 2025
- 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.