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Ingredient

Limonene

Provides a citrus-like fragrance.

At a glance

Function
Fragrance
Origin
Plant-derived (citrus oils)
Product areas
Hair care, Hair styling

What it is

Limonene is the fragrance that gives citrus peel its smell, and it is overwhelmingly obtained from exactly that — as a by-product of juice production. Of the four records in this block it is the only one whose stated origin stood up to checking.

The finding is the same as with linalool: fresh, the substance is barely an allergen; in air it oxidises and forms hydroperoxides, and those are potent contact allergens. Because limonene also occurs in cleaning products, air fresheners and food, total everyday exposure is high — and what share of it comes from cosmetics is open.

Assessment

Result
Increased attention
Confidence
medium
Evidence
B — well established
Applies to
Cosmetics, external use on hair and scalp; rinse-off as well as leave-on products; the assessment refers to the substance including its oxidation products; concentration and degree of oxidation not documented

Why

  • Why the classification reads “increased attention”: oxidised limonene is among the fragrances that produce the most positive test results in dermatology clinics. The test preparations have been in use for decades and, according to a 2019 review, have been applied to more than twenty thousand people in total.
  • The pure substance is not the problem here either. Pure limonene is regarded, on the basis of animal tests and test series, as at most a very weak sensitiser. What is assessed is the oxidised form, and it arises in the product itself.
  • Stated origin checked and confirmed. The short field names citrus oils, and that is correct — limonene arises in large quantities during the processing of citrus fruit. It is thus the only one of the four records in this block whose origin remains unchanged. This has no effect on the assessment: plant origin says nothing about tolerability, and this substance is the best example of that in the whole lexicon.
  • According to the review named below, the hydroperoxides of limonene and linalool are currently not part of the European baseline test series. Anyone with a suspicion therefore has to ask for them specifically — the standard series alone will not necessarily find such an allergy.
  • Age and storage decide the matter. What applies to linalool applies equally here: the ingredient list says nothing about how far oxidation has progressed in the actual jar. Until 10.09.2026 the short field additionally called the substance an “aroma component” — a term from the food sector that does not belong here; it was removed in all four languages.

When the assessment differs

  • Known allergy to oxidised limonene: then the product is unsuitable. What is tested is the oxidised form, not the pure substance.
  • Existing eczema or atopic dermatitis: a lower threshold for sensitisation.
  • Old or long-opened products: the longer air reaches the formulation, the more oxidation products can form.
  • High everyday exposure: anyone dealing a lot with citrus-scented cleaning products at work or at home adds that exposure to the cosmetic one.
  • Occupational contact in the salon: daily contact with many fragranced products on the hands.

Open questions

  • Concentration in the specific product: not available.
  • Degree of oxidation in the specific product: not determinable.
  • Share of cosmetics in total exposure: open. Limonene is just as widespread in cleaning products, scented candles and food.
  • The 2019 analytical market survey did not find the hydroperoxides in commercial products in the amounts that would explain the high test frequency. The contradiction is unresolved.
  • Regulatory status and the rules on individual naming: not checked; they are not quoted second-hand.

Sources for this assessment

Applies to: Fragrance materials

Further substances from the same group for which a long-form assessment already exists.

Assessment last reviewed:

Recorded in the following products

This list documents the products in which the ingredient was declared at the time of recording. It is not a statement about those products and not a recommendation. Manufacturers change formulations; the ingredient list on the current packaging is always authoritative.

  • Keep Curl, Status Quo, Power Build, Soothe Plus
  • Status Quo, Power Build, Soothe Plus, Keep Curl
  • Power Build Treatment, Power Build Revamp, Aqua Boost
  • Wella Nutricurls Micellar Curls Shampoo
  • Kérastase Première Bain Décalcifiant Réparateur
  • Kérastase Chroma Absolu Bain Chroma Respect
  • Matrix Controller Gel
  • Matrix Over Achiever 3-in-1
  • Matrix Setter Mousse
  • Matrix Fixer Hairspray

Sources documenting its occurrence

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