At a glance
| Chemical family | A phenylpropene; a structural isomer of eugenol, but a distinct allergen metabolized by a different pathway. Occurs in ylang-ylang and nutmeg oils |
| CAS number | 97-54-1 |
| Classification | Not IARC-classified (absence of evaluation, not a safety finding). One of the most potent contact allergens in routine fragrance use; a constituent of Fragrance Mix I and an EU-declared fragrance allergen |
| Where you encounter it | Ylang-ylang and nutmeg oils; fragrance in perfumes, soaps, detergents and personal-care products; spice and carnation accords |
| Sleep micro-environment relevance | Fragrance that survives laundering and sits against the skin all night; for the fragrance-allergic, a pillowcase is eight hours of warm, occluded contact with a strong allergen |
| Activated carbon capture | Not the main lever — the exposure that matters is skin contact with treated fabric, so fragrance-free laundry is the direct fix |
What it is
Isoeugenol is a phenylpropene with a warm, spicy, carnation-like odour. It occurs in ylang-ylang and nutmeg oils and is used widely as a fragrance in perfumes, soaps, detergents and personal-care products. Peer-reviewed — Buckley et al. 2006
Isoeugenol is not IARC-classified; it does not appear in the IARC list of classified agents. Inferred — isoeugenol does not appear in the IARC list of classified agents; that is an absence of evaluation, not a finding of safety So this is not a cancer page. It is an allergy page, and on that measure isoeugenol is near the top of the list: it is potent enough that the EU restricts its concentration in cosmetics rather than simply requiring it to be declared. Regulatory — EU 2023/1545
How it relates to the bedroom
The fragrance that survives the wash
Cinnamal's bedroom route is ordinary fragrance. It is used in soaps, detergents and household products, and laundry scent is engineered to persist on fabric, so it remains on washed bedding pressed against skin. Inferred — from isoeugenol's documented use as a soap and detergent fragrance and the designed persistence of laundry scent; isoeugenol specifically has not been measured on laundered bedding For most sleepers this is unremarkable. For someone sensitized to isoeugenol, it is a nightly, warm, occluded dose to the face and neck.
A Fragrance Mix I allergen, and not the same as eugenol
Isoeugenol is one of the eight constituents of Fragrance Mix I, the standard screening mix for fragrance allergy. In a series of 23,660 patients patch-tested to the European standard series, 7.7% reacted to Fragrance Mix I. Peer-reviewed — Buckley et al. 2006
The name invites a conflation worth resisting. Isoeugenol and eugenol are structural isomers, but they are metabolized by different pathways and only partly cross-react. Of 231 patients allergic to isoeugenol, 22% were also allergic to eugenol, against 12.4% of isoeugenol-negative patients. Peer-reviewed — Buckley et al. 2006 The overlap is real but modest, which is exactly why both are kept in the mix and tested separately: an isoeugenol allergy will not reliably show up as a eugenol reaction, or the reverse. Peer-reviewed — Buckley et al. 2006
Declared on EU labels
Cinnamal is one of the fragrance allergens the EU requires to be declared on cosmetic labels above set thresholds (0.001% leave-on, 0.01% rinse-off), under Commission Regulation (EU) 2023/1545, with full compliance from 31 July 2026. Regulatory — EU 2023/1545 For a diagnosed isoeugenol allergy, that declaration is the practical avoidance tool.
What the research says
- Not IARC-classified. Isoeugenol does not appear in the IARC list; an absence of evaluation, not a safety finding. Inferred
- A Fragrance Mix I constituent. 7.7% of 23,660 patch-tested patients reacted to Fragrance Mix I. Peer-reviewed — Buckley et al. 2006
- Only partly overlapping with eugenol. 22% of isoeugenol-allergic patients also reacted to eugenol, versus 12.4% of the isoeugenol-negative. Peer-reviewed — Buckley et al. 2006
- Must be tested separately. An isoeugenol allergy will not reliably show as a eugenol reaction, or the reverse. Peer-reviewed — Buckley et al. 2006
- EU-restricted, not just declared. Potent enough that its concentration in cosmetics is capped. Regulatory — EU 2023/1545
What helps reduce it
Use fragrance-free detergent on bedding. For an isoeugenol-allergic sleeper this is the single highest-yield change, because it removes a strong allergen from eight hours of occluded skin contact. Inferred
Do not assume a eugenol-free product is isoeugenol-free. They are separate declarations and only partly co-react. Peer-reviewed — Buckley et al. 2006
Read the EU allergen declarations. Isoeugenol must be named above threshold. Regulatory — EU 2023/1545
What does NOT help
- Treating it as a cancer risk. Isoeugenol is not IARC-classified; the documented hazard is contact allergy. Inferred
- Assuming it is interchangeable with eugenol. They are isomers with different metabolism and only partial cross-reaction. Peer-reviewed — Buckley et al. 2006
Open research questions
- How much isoeugenol actually persists on laundered bedding from detergent fragrance — not measured. Speculation
- Whether the EU concentration cap has measurably reduced isoeugenol sensitization rates over time. Speculation
Citations
- Buckley DA, Basketter DA, Smith Pease CK, Rycroft RJG, White IR, McFadden JP (2006). Simultaneous sensitivity to fragrances. British Journal of Dermatology 154(5):885–888. Of 23,660 patients patch-tested to the European standard series, 1,811 (7.7%) reacted to Fragrance Mix I. Of 231 patients allergic to isoeugenol, 50 (22%) were also allergic to eugenol, versus 12.4% of isoeugenol-negative patients — a modest overlap, consistent with the two being metabolized by different pathways and warranting separate testing. PMID 16634891. doi.org/10.1111/j.1365-2133.2006.07170.x Peer-reviewed
- Commission Regulation (EU) 2023/1545 amending Regulation (EC) No 1223/2009 as regards labelling of fragrance allergens (Annex III). Isoeugenol must be declared on cosmetic labels above 0.001% (leave-on) / 0.01% (rinse-off); compliance from 31 July 2026. EUR-Lex Regulatory
Frequently asked questions
What is isoeugenol?
Isoeugenol is a phenylpropene with a warm, spicy, carnation-like odour. It occurs in ylang-ylang and nutmeg oils and is widely used as a fragrance in perfumes, soaps and detergents. It is a structural isomer of eugenol, but the two are separate allergens. In the bedroom it reaches you as fragrance that persists on laundered bedding.
Is isoeugenol a carcinogen?
Isoeugenol does not appear in the IARC list of classified agents, so it has no IARC carcinogenicity classification. That is an absence of evaluation rather than a finding of safety. Its documented hazard is skin sensitization, where it is one of the strongest fragrance allergens in routine use.
How allergenic is it, and is it the same as eugenol?
Isoeugenol is one of the eight constituents of Fragrance Mix I; 7.7% of 23,660 patients patch-tested to the European standard series reacted to that mix. It is not the same as eugenol: they are structural isomers metabolized by different pathways, and cross-reaction is only partial. Of 231 patients allergic to isoeugenol, 22% were also allergic to eugenol, against 12.4% of isoeugenol-negative patients. So the two must be tested separately.
Should I be worried about it?
If you have no fragrance allergy, no. If you have fragrance-allergic dermatitis, isoeugenol is one of the most likely culprits, and it is potent enough that the EU restricts how much may be used rather than merely requiring it on the label. A fragranced pillowcase means eight hours of warm, occluded contact, so fragrance-free bedding laundry is the direct fix.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-14. If you find a factual error, contact us.