Fragrance allergen

Woody amber musk

Tetramethyl acetyloctahydronaphthalenes, usually called OTNE, is a synthetic woody-amber fragrance ingredient, and Iso E Super is one of its trade names. The commercial product is a mixture of isomers, not one molecule. It is one of the highest-volume ingredients in perfumery.

Where it comes from

ScenTree says Iso E Super, an OTNE product, is not available in its natural state. It describes it as made from myrcene and 3-methyl-3-penten-2-one in the presence of aluminium chloride, then treated with phosphoric acid to form its ring structure. ScenTree also says it is a mix of more than 20 isomers, including a strongly smelling one called Arborone, at 2 to 5 per cent.

Smell and use

A dry woody smell with an ambergris-like quality. ScenTree lists woody, ambergris, violet flower and cedar notes, and says it can bring a light violet flower note to woody accords.

OTNE is used as a dry woody-amber base material rather than as a top note. ScenTree describes Iso E Super as used in masculine, woody and ambery notes as a woody base, and as stable in perfumes and diverse functional bases. The US National Toxicology Program found OTNE in more than 30 consumer product types.

On the label

Named on 12% of the 6,851 perfume ingredient lists we hold (816 perfumes).

Printed as
Tetramethyl acetyloctahydronaphthalenes
EU
Annex III, entry 344. Must be named above 0.001% in leave-on products (0.01% rinse-off).
Great Britain
Not on Great Britain's list, so a GB label need not name it. The EU list does.

SCCS/1459/11 (2012) lists it among established contact allergens in humans, marked + (up to 10 reported positive test reactions). The 2023 EU label listing is a labelling duty, not a concentration restriction; IFRA separately has a Restriction standard for it (2020). In PubChem's summary of ECHA company reports, 89.5% say it may cause an allergic skin reaction. One industry source says Great Britain has not adopted the 2023 expansion.

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 12% of 4,929
  • Eau de toilette 7% of 1,228
  • Extrait 11% of 341
  • Parfum 43% of 194
  • Cologne 6% of 121
  • Body spray 37% of 49
  • Other 19% of 27

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

Named alongside

Share of the lists naming Woody amber musk that also name each of these.

Notes whose materials include it

Perfumes whose box names it

Common questions

What does OTNE (Iso E Super) smell like?

A dry woody smell with an ambergris-like quality. ScenTree lists woody, ambergris, violet flower and cedar notes, and says it can bring a light violet note to woody accords.

Is OTNE natural or synthetic?

Synthetic. ScenTree says Iso E Super, an OTNE product, is not available in its natural state. It describes it as made from myrcene and 3-methyl-3-penten-2-one, then treated with phosphoric acid to form its ring structure.

Why is tetramethyl acetyloctahydronaphthalenes on my perfume label?

It is the legal label name for OTNE, added by Regulation (EU) 2023/1545. Brands must show it once it exceeds 0.001 per cent in leave-on products or 0.01 per cent in rinse-off ones.