Worth a closer look
Evidence key Strong Moderate Weak How we grade
Labeled fragrance allergen (EU) Skin allergen Oxidizes into stronger allergens
- What it can be used for
- Adds scent, dissolves other ingredients and reduces or masks body odor (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
- CAS number
- 138-86-3
Why it’s flagged
A fragrance allergen the EU requires companies to name on the label.
- Annex III entry 88. 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. 1 (H317). Source: EU CLP Regulation, Annex VI harmonized classification
- Skin Sens. 1B (H317). Source: EU CLP Regulation, Annex VI harmonized classification
EU hazard statement H317: may cause an allergic skin reaction.
Reacts with air to form stronger skin allergens.
- Forms allergenic hydroperoxides when exposed to air. Source: ihateperfume.com graded evidence
These scent chemicals react with air once a product is opened and form hydroperoxides, which are much stronger skin allergens. See the graded evidence below.
What the research says
- Oxidized forms of limonene and linalool, formed when these common fragrance terpenes react with air, are now treated as a standard, distinct fragrance-allergen category in mainstream dermatology, alongside fragrance mix I/II and balsam of Peru. Strong evidence. Aristizabal-Torres 2025
- Among 5,773 people tested for eczema at a Swedish hospital, 9.4% were allergic to the air-oxidized forms of two of the most widely used scent chemicals: linalool (7.0%) and limonene (5.1%). Strong evidence. Sukakul 2022
- The industry once allowed the allergen citral only if mixed with a companion terpene (originally tested at about 20% d-limonene, later mandated at ≥25%), claiming the terpene 'quenched' the allergic reaction; the original 1976 evidence for this was a single unreplicated human test with no subject numbers reported and was already internally inconsistent, later industry HRIPTs could not reproduce quenching for a related aldehyde (cinnamaldehyde), and air-oxidized limonene, the proposed quencher, is itself now one of the commonest fragrance allergens (about 5% of patients tested). Strong evidence. Ford 1994 (RIFM) Industry-funded
- Limonene and linalool become skin allergens when they react with air: in European dermatitis clinics, 3.9-20% of patients tested reacted to oxidized linalool and 1.4-13.7% to oxidized limonene, against under 1% for the fresh chemicals. Strong evidence. Ogueta 2022
- Limonene was detected in every childcare room studied and was more than 1,000 times higher indoors than outdoors, so it came from products used inside. Strong evidence. Hoang 2016
- Scientists can identify which everyday products are polluting a city's outdoor air just by measuring a handful of specific chemical fingerprints: a silicone compound (D5-siloxane) for personal-care products and citrus/pine-scent chemicals (monoterpenes, mostly limonene) for fragranced products, confirmed by mobile-lab measurements across New York City, Pittsburgh, Chicago and Denver. Strong evidence. Gkatzelis 2021
- Scent-type chemicals typical of fragranced and cleaning products (limonene, pinene, carene) were the signature of home air: close to zero outdoors but tens to hundreds of times higher inside homes. Strong evidence. Gokhale 2008
- In week-long air measurements across 11 European cities, the scent chemicals limonene and alpha-pinene were the compounds most concentrated in homes compared with workplaces (about 4x), attributed to perfumes, cleaning and fragranced products. Strong evidence. Geiss 2011
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
- Many fragrance chemicals become stronger skin allergens after the bottle is opened: limonene, linalool and geraniol react with air at room temperature to form hydroperoxides that, in mouse tests, sensitize at 5-10 times lower concentrations than the fresh chemical. Strong evidence. Pastor-Nieto 2021 (Karlberg 2013)
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.