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Alpha-Isomethyl Ionone

What Alpha-Isomethyl Ionone is & what it does

A soft, violet-like fragrance compound used to perfume formulas. It is a recognized fragrance allergen.

What is Alpha-Isomethyl Ionone and what does it do in sunscreen?

Alpha-Isomethyl Ionone is a fragrance ingredient with a soft, violet-like, slightly woody scent. In a sunscreen it is part of the perfume blend, added to make the product smell pleasant and to mask the raw smell of the filters and oils. It has no role in sun protection and is purely there for scent.

Is Alpha-Isomethyl Ionone safe?

For most people, yes, but it is a recognized fragrance allergen. EU rules require it to be named on the label rather than hidden under "parfum" precisely so that sensitized people can spot it. At the small amounts used in sunscreen it is fine for the majority, but anyone with a known fragrance allergy may want to avoid it.

Is Alpha-Isomethyl Ionone a common allergen?

Yes, it is on the EU's list of fragrance substances that must be declared because they can trigger contact allergy in some people. Most users tolerate it without any issue, but those prone to fragrance reactions or with sensitive or eczema-prone skin may prefer fragrance-free sunscreens. A patch test is sensible if you are unsure.

Does Alpha-Isomethyl Ionone clog pores?

Generally no. As a fragrance molecule used in tiny amounts, it is not a pore-clogging ingredient. The concern with this ingredient is potential allergy or irritation in sensitive people, not comedogenicity.

What is Alpha-Isomethyl Ionone on an ingredient list (INCI)?

"Alpha-Isomethyl Ionone" is the INCI name you will see broken out near the end of the ingredient list, usually grouped with other named allergens like Linalool or Limonene. It appears separately because labeling rules require listed fragrance allergens to be called out by name even when the rest of the scent is bundled as "Parfum" or "Fragrance."

Sunscreens with Alpha-Isomethyl Ionone

We rate 339 sunscreens that contain it, showing the top 10 by overall score:

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