Fragrance allergen

Hydroxycitronellal

Hydroxycitronellal is a man-made floral aldehyde whose scent recalls lily of the valley, known in perfumery as muguet. It is made from citronellal and used in floral blends. EU rules require it to be named on cosmetic labels above set concentrations.

Formula
C10H20O2
Molar mass
172.27 g/mol
CAS
107-75-5

Where it comes from

Chemically it is citronellal with water added across one double bond, and industry makes it from citronella aldehyde (citronellal). Sources describe it as a synthetic fragrance. A natural-product database reports it in clary sage (Salvia sclarea), but that is a single occurrence report and says nothing about how perfume grades are supplied.

Smell and use

Sweet and floral, mild and delicate at first, resembling lily of the valley. The Good Scents Company lists floral, lily, sweet, green, waxy and a tropical melon facet, at medium odour strength.

Arctander called it one of the most frequently used floralising perfume materials. Originally introduced as a muguet material, he wrote, it finds its way into almost every type of floral fragrance and a great many non-floral ones. He called it almost a 'must' in muguet (at certain price levels) and in peony, lily, sweet pea, narcisse and linden blossom.

On the label

Named on 40% of the 6,851 perfume ingredient lists we hold (2,724 perfumes).

EU
Annex III, entry 72. Must be named above 0.001% in leave-on products (0.01% rinse-off).
Great Britain
Required, same thresholds. GB Annex III
Patch tests
In Fragrance Mix I, a standard skin-clinic panel.

Hydroxycitronellal is on the EU list of fragrance allergens that must be named on cosmetic labels. The SCCS opinion SCCS/1459/11 (2012) lists it in Table 13-5, established fragrance contact allergens of special concern. Companies notifying ECHA overwhelmingly report H317, may cause an allergic skin reaction; these are company notifications, not a harmonised classification. IFRA has a Standard that restricts the quantity used. In May 2026 the SCCS published a Commission mandate to assess it again.

A list that does not name it does not prove it is absent: brands only have to name it above the threshold.

Frequency by concentration

  • Eau de parfum 40% of 4,889
  • Eau de toilette 44% of 1,227
  • Extrait 29% of 341
  • Parfum 45% of 194
  • Cologne 34% of 114
  • Body spray 29% of 42
  • Other 15% of 27

Share of the perfumes we hold a list for, in each concentration.

Named alongside

Share of the lists naming Hydroxycitronellal that also name each of these.

Perfumes whose box names it

Common questions

What does hydroxycitronellal smell like?

Lily of the valley. It is a sweet, delicate floral note with green and slightly tropical, melon-like touches. Perfumers use it as a classic muguet material and in other floral accords such as lily, peony and sweet pea.

Is hydroxycitronellal natural or synthetic?

Sources call it a synthetic fragrance, made industrially from citronellal (citronella aldehyde). One natural-product database lists it in clary sage, but that report does not describe how perfume grades are supplied.

Why is hydroxycitronellal on my perfume label?

It is one of the fragrance allergens EU cosmetics law lists by name, so it must appear when present above 0.001% in leave-on or 0.01% in rinse-off products. The SCCS listed it as an established contact allergen in 2012.