Hydroxycitronellal
3,7-Dimethyl-7-hydroxyoctanal
What it is
A synthetic fragrance aldehyde with a soft sweet lily-of-the-valley scent, one of the most widely used floral notes in perfumery.
In this product: Fragrance. A sweet lily-muguet floral note.
Dose & route, what actually matters
Allergic contact dermatitis from leave-on skin exposure in sensitised people. Not a general-population systemic hazard at normal use.
EUROPEAN UNION
Annex III declarable fragrance allergen, reaffirmed as still relevant by SCCS/1459/11 and Commission Regulation (EU) 2023/1545. Named on EU labels above 0.001% leave-on / 0.01% rinse-off.
UNITED STATES
No restriction. Hides under “Fragrance” unless disclosed.
The evidence
Hydroxycitronellal is one of the eight components of Fragrance Mix I, the standard clinical patch-test battery used to diagnose fragrance contact allergy.
human · 2012 · source
It is an EU Annex III declarable fragrance allergen, reaffirmed as still relevant by SCCS/1459/11 and Commission Regulation (EU) 2023/1545.
regulatory · 2023 · source
California Prop 65: Not listed.
How to avoid it
Look for “hydroxycitronellal” on EU labels. Lily-of-the-valley and floral-bouquet fragrances are the high-risk type. Fragrance-free is the only reliable avoidance for sensitised skin.
Where it hides
Editorial analysis of publicly available regulatory and peer-reviewed sources. Not medical advice. We name our evidence and link it, including when an ingredient is fine.