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Cosmetic ingredient dictionary

Alpha-Isomethyl Ionone in cosmetics: what it is and what it does

Alpha-Isomethyl Ionone is a cosmetic ingredient that keeps the skin in good condition. The EU allows it only with limits or conditions. It is a fragrance allergen that EU labels must name above set levels. Open Beauty Facts finds it in 1,360 products, most often deodorants.

By Bravoora teamUpdated Sources checked 4 sourcesHow we check

Not for you

for a fragrance-sensitive skin profile

What does Alpha-Isomethyl Ionone do in a product?

In a cosmetic product, Alpha-Isomethyl Ionone keeps the skin in good condition and adds scent. The EU’s CosIng database lists these jobs for it: skin conditioning and perfuming.

skin conditioningperfuming

What other names and numbers does Alpha-Isomethyl Ionone have?

CAS number
127-51-5
EC number
204-846-3
CosIng reference
39665

Is Alpha-Isomethyl Ionone restricted in the EU?

Yes, it has limits. The EU allows it only with limits or conditions of use, such as a maximum amount or a warning on the label (Annex III of Regulation 1223/2009, entry 90).

The annex entry sets the exact limits, the products it may be used in and any warning the label must carry.

Is Alpha-Isomethyl Ionone a fragrance allergen?

Yes. Alpha-Isomethyl Ionone is one of the fragrance allergens that EU rules make a label name when there is more than 0.001% of it in a product left on the skin, or more than 0.01% in one that is rinsed off. On a label it can appear on its own after “Parfum”, because it is part of the scent.

Who should look out for Alpha-Isomethyl Ionone?

Fragrance-sensitive skinNot for youIt is a fragrance allergen EU rules name.

Read the fragrance (parfum) guide

Which products contain Alpha-Isomethyl Ionone?

Open Beauty Facts finds Alpha-Isomethyl Ionone in the ingredient lists of 1,360 of the 22,021 products it has a list for, most often deodorants, hair care and body care.

  • Deodorants166
  • Hair care64
  • Body care58

Products with it, by country of sale: France 497 · Germany 196 · United States 97 · Morocco 63.

Counted on 13 October 2026 from Open Beauty Facts, which volunteers fill from real packs: it shows where Alpha-Isomethyl Ionone turns up, not how much of the market it is.

On these listsFragrance allergensRestricted in the EU

Bravoora reads this ingredient for everyone you shop for: an allergy or intolerance, a vegan or vegetarian diet, a calorie or protein goal, and the labels on supplements and skincare too. Build a profile · For dermatologists, dietitians and doctors

Sources

The job, the description and the EU annex entry are CosIng’s; the fragrance allergens are the EU Annex III names Bravoora’s label checker reads; the product counts are Open Beauty Facts’.

  1. European Commission: CosIng cosmetic ingredient database (functions, description, EU annex entry)
  2. Open Beauty Facts: product database, 77,506 products, read 13 October 2026, ODbL
  3. EU Regulation 1223/2009 on cosmetic products (the annexes)
  4. EU Regulation 2023/1545 (fragrance allergen labelling)

Contains information from Open Beauty Facts, which is made available here under the Open Database License (ODbL). Read the licence · Download this dictionary’s data · How we check

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