Alpha Isomethyl Ionone


Fragrance Synthetic and Natural

No known benefits

Alpha Isomethyl Ionone at a glance

  • Has a strong, flowery scent
  • Research shows it can cause allergic skin reactions
  • Considered an allergen in the European Union
  • One of the scent components of Chanel No. 5

Alpha Isomethyl Ionone description

Volatile fragrance and flavoring ingredient that must be listed on products that contain it due to its risk of causing a sensitised reaction at concentations as low as 0.001%. It’s an ingredient to avoid if you have sensitive skin, especially because it’s almost always combined with other volatile fragrance components such as linalool and eugenol.

Alpha Isomethyl Ionone references

  • Regulatory Toxicology and Pharmacology, August 2022, pages 1–6
  • Current Chemistry Letters, October 2021, pages 435-444
  • Journal of Preventive Medicine and Hygiene, March 2019, pages E50-E57
  • Journal of Pharmaceutical and Biomedical Analysis, July 2007, pages 755-562
  • Contact Dermatitis, December 2005, pages 320-323
  •, Website

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated

We have not yet rated this ingredient because we have not had a chance to review the research on it.