Ingredient Beauty BenefitsOther · An ingredient class — not a single line on an ingredient list
If the ingredient list names a substance instead of saying 'fragrance', a rule made it do that
Korean regulation names 25 fragrance allergens and requires that, above a set threshold, they be written out by name rather than folded into the word 'fragrance'. The thresholds are above 0.01% in rinse-off products and above 0.001% in leave-on products. All 25 are transcribed below with their CAS numbers.
Last checked Sep 18, 2026
- In pregnancy
- Not established
- Irritation
- High
- Daytime use
- ✓ Fine
Not a measurement — reported irritation grouped into five steps. It varies between people.
This page is not about efficacy. It is about how to read an ingredient list.
You have seen the line near the end of a cosmetic ingredient list that says only 'fragrance'. Behind that one word there can be dozens of substances, and companies do not disclose them, citing perfumery trade secrets.
There are, however, 25 exceptions. Twenty-five substances known to cause contact allergy cannot hide behind the word 'fragrance' once they exceed a set threshold. They have to appear under their own names.
So when you see limonene, linalool or citronellol on a label — the company did not write that out of generosity; a rule required it. And the very fact that the name is there tells you the amount crossed the threshold.
For anyone who has reacted to a scent, this list is practically useful. Conversely, being on the list does not make a substance 'dangerous'. For most people, nothing happens.
Contents
What is established
The same ingredient at a different strength, in a different formula, is a different product. These are the conditions the studies used.
The 25 names and CAS numbers, as the annex has them
This is the full content of Annex 2 of the Regulation on Precautions for Use and Labelling of Allergenic Fragrance Ingredients, transcribed from the original on the Korean national law portal on 18 September 2026.
First, the proviso at the top of the annex:
Provided that this applies only where the content exceeds 0.01% in products that are rinsed off after use and 0.001% in products that are not rinsed off after use.
The threshold for leave-on products is ten times stricter, because the contact time is different.
The 25 are:
- Amyl cinnamal (CAS No 122-40-7)
- Benzyl alcohol (CAS No 100-51-6)
- Cinnamyl alcohol (CAS No 104-54-1)
- Citral (CAS No 5392-40-5)
- Eugenol (CAS No 97-53-0)
- Hydroxycitronellal (CAS No 107-75-5)
- Isoeugenol (CAS No 97-54-1)
- Amylcinnamyl alcohol (CAS No 101-85-9)
- Benzyl salicylate (CAS No 118-58-1)
- Cinnamal (CAS No 104-55-2)
- Coumarin (CAS No 91-64-5)
- Geraniol (CAS No 106-24-1)
- Anise alcohol (CAS No 105-13-5)
- Benzyl cinnamate (CAS No 103-41-3)
- Farnesol (CAS No 4602-84-0)
- Butylphenyl methylpropional (CAS No 80-54-6)
- Linalool (CAS No 78-70-6)
- Benzyl benzoate (CAS No 120-51-4)
- Citronellol (CAS No 106-22-9)
- Hexyl cinnamal (CAS No 101-86-0)
- Limonene (CAS No 5989-27-5)
- Methyl 2-octynoate (CAS No 111-12-6)
- Alpha-isomethyl ionone (CAS No 127-51-5)
- Evernia prunastri (oak moss) extract (CAS No 90028-68-5)
- Evernia furfuracea (tree moss) extract (CAS No 90028-67-4)
The CAS numbers are here for a reason. The same substance is written differently across countries and products. Limonene appears as d-limonene or Limonene; butylphenyl methylpropional turns up under other common names on foreign labels. A CAS number is unique to one substance, so when the names are confusing, checking the number settles it.
One thing worth flagging: number 2, benzyl alcohol, is also used as a preservative. So seeing benzyl alcohol on a label does not mean it is necessarily there for scent. It is the one name on this list that moves between two roles.
And numbers 24 and 25 are extracts — not single substances but mixtures pulled from lichen, and the label does not tell you what is inside them or in what proportion.
The absence of a name does not mean the substance is absent
This is the most important item on the page.
The labelling duty arises only above the threshold. So if a label shows none of the 25 and only the single line 'fragrance', there are two possibilities:
- None of the 25 is present
- One or more is present but below the threshold (0.001% or less in a leave-on product)
The ingredient list cannot distinguish between these two.
0.001% looks like a small number, but contact allergy can provoke a reaction at very low concentrations in someone already sensitised. So the inference 'not on the label, therefore safe' does not hold.
Turned around: this list can be used to learn that something is present, but not to guarantee that something is absent.
If patch testing has told you that you react to a particular fragrance substance, reading labels is not enough on its own and fragrance-free products are the direction to look. That said, we have found no source on the legal definition of 'fragrance-free' or how it is verified, so how far that label can be trusted is a question this page cannot answer.
That is why this item is filed as 'not established'. We confirmed what the regulation requires; we did not find a source establishing how much the regulation actually reduces allergic reactions.
A 2025 review still puts fragrances first
A 2025 review of contact allergy in cosmetics records that fragrances remain the most prevalent cosmetic allergens.
Why this item sits outside the evidence-strength ladder, as 'ingredient data': it is not an efficacy claim, and it is not a clinical trial we graded ourselves. It is a fact the literature reports repeatedly. The badges on this site measure 'does this ingredient work', which is not the question here.
But the fact gives context to the two items above. Why do fragrances alone get a labelling rule like this? There is no list of 25 for preservatives, or for surfactants. Fragrances have one because they are the most common cause of contact allergy; the regulation follows the fact.
One part needs reading carefully. 'Most prevalent' means most prevalent among people who came in for patch testing. It is a statistic about people who went to a dermatologist, not about the general population. What share of people using fragrance react is not something this source tells you.
How to use it
- There is no 'how to use' here. This is not something you apply; it is a way of reading a label.
- If you have reacted to a scent, write down which of the 25 appeared on the label of the product that caused it. You will have something to compare against next time.
- When names confuse you, match on the CAS number. Translated names wobble; the number does not.
- Leave-on products (creams, serums, sunscreens) carry a threshold ten times stricter. The same name on the label implies a different amount depending on the product type.
Cautions
- Being on the list does not make a substance 'bad'. For most people, nothing happens.
- Being absent from the label does not mean absent from the product. Below the threshold, it is not written.
- If contact allergy is suspected, patch testing is more accurate than guessing from labels. Diagnosis belongs to clinicians.
- This list is the Korean notice. Labels on imported products follow their own country's rules, so both the list and the thresholds may differ.
With a new ingredient, apply a small amount somewhere inconspicuous, such as the inner arm, for two days first. Stop if it reddens or stings.
Related skin concerns
What this article relies on
- 화장품 사용할 때의 주의사항 및 알레르기 유발성분 표시에 관한 규정 [별표 2] 착향제의 구성 성분 중 알레르기 유발성분 — 식품의약품안전처고시 제2026-56호식품의약품안전처 · 시행 2026-08-05 · Checked on 2026-09-18
- PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16