Fragrance allergen

Alpha-Terpinene

Alpha-terpinene is a monoterpene that smells of lemon and wood, with a herbal, slightly medicinal edge. It is used in flavours and in fragrances to extend citrus effects. The SCCS identifies it as a prehapten, a substance whose sensitising potency rises on air exposure, and it appears in the EU's 2023 allergen update.

Formula
C10H16
Molar mass
136.24 g/mol
CAS
99-86-5

Where it comes from

Alpha-, beta- and gamma-terpinene are monoterpene isomers that differ in the positions of their two double bonds. Alpha-terpinene is isolated from cardamom and marjoram oils, and the SCCS refers to alpha-terpinene from tea tree oil. Natural occurrence does not show where the material in a particular perfume comes from.

Smell and use

Woody, terpenic and lemony, with herbal, medicinal and citrus facets. Perfumery sources also describe it as sharp and juicy, with camphoraceous and thymol notes.

It is widely used in flavour and fragrance work to reconstitute and extend citrus oils, according to one supplier. It is also listed as a flavouring agent and as a component of a terpenoid blend used as a crop insecticide. Suppliers further mention pharmaceutical and electronics manufacturing uses.

On the label

Named on 7% of the 6,851 perfume ingredient lists we hold (488 perfumes).

EU
Annex III, entry 131. Must be named above 0.001% in leave-on products (0.01% rinse-off).
Great Britain
Not on Great Britain's list. It came to the EU list in 2023 and a GB label need not name it.

The SCCS opinion SCCS/1459/11 lists alpha-terpinene as a prehapten, whose sensitising potency can rise on air exposure through oxidation, and as an established prohapten, activated by metabolism. A regulatory summary of Regulation (EU) 2023/1545 includes it among the new or amended Annex III entries and says the 0.001% leave-on and 0.01% rinse-off naming thresholds apply to that list. A reference table gives a peroxide value limit of below 10 mmoles/L for it. Among company reports summarised by PubChem that give hazard codes, 16.1% include 'may cause an allergic skin reaction'.

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 7% of 4,898
  • Eau de toilette 5% of 1,227
  • Extrait 6% of 341
  • Parfum 26% of 191
  • Cologne 2% of 108
  • Body spray 7% 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 Alpha-Terpinene that also name each of these.

Perfumes whose box names it

Common questions

What does alpha-terpinene smell like?

It smells of lemon and wood, with herbal and slightly medicinal sides. Descriptions range from refreshingly herbaceous-citrusy to sharp and terpenic. They also mention camphoraceous and thymol notes.

Is alpha-terpinene natural or synthetic?

It occurs in plants: it is isolated from cardamom and marjoram oils and is present in tea tree oil. Natural occurrence does not show where the alpha-terpinene in a given perfume comes from.

Why is alpha-terpinene on my perfume label?

A regulatory summary of Regulation (EU) 2023/1545 includes it in the list of Annex III entries, with thresholds of 0.001% in leave-on and 0.01% in rinse-off products. The same page says prehaptens and prohaptens, which can turn into known contact allergens, are treated like fragrance allergens.