Eugenol

What it is

Eugenol is the main component of clove oil and carries its spicy note into four products in this lexicon. It also occurs in cinnamon, basil, bay leaf and allspice and is used in dentistry as a component of zinc oxide eugenol cements.

Unlike the three terpenes of the preceding blocks, ageing is not the topic here. Eugenol is part of the fragrance mix used in dermatology clinics to search for fragrance allergies — it is one of the classic touchstones and has been described as a contact allergen for decades.

Why

• Why the classification reads “increased attention”: eugenol is part of the fragrance mix used in the European baseline series to search for fragrance allergies. Its inclusion rests on decades of observation — the substance is not tested because it is suspect but because it has proved effective at revealing allergies.
• A 2023 study at six European dermatology clinics yields a finding that reaches beyond this substance. Of 34 people with a confirmed eugenol allergy, only 21 — just under 62 per cent — showed a positive patch test reaction. In a three-week use test, 19 reacted, just under 56 per cent. A negative test therefore does not reliably rule out the allergy.
• The lowest concentration that still elicited a reaction in that study was 0.031 per cent. That is a very small value and the reason why, with a known eugenol allergy, even small amounts in a product count.
• The stated origin remains unchanged and is thus — as with limonene in the eleventh block — one of the few that stands up to checking. Eugenol is overwhelmingly obtained from clove oil. This has no effect on the assessment: the substance is of plant origin and nevertheless one of the best-described contact allergens in cosmetics.
• The cross-reactions reach beyond cosmetics. Anyone reacting to eugenol may also react to clove, cinnamon, basil and balsam of Peru — and to dental materials. For advice at the chair, this is the point where an apparently purely cosmetic topic connects with the client's everyday life. Until 11.09.2026 the short field gave only “provides fragrance” as the reason; it now describes the scent note.

When the assessment differs

• Known eugenol allergy: then the product is unsuitable. Because of the very low eliciting concentration, small amounts count here too.
• A negative test where suspicion remains: according to the study used, a negative result does not reliably rule out the allergy. Judging the individual case belongs in medical hands.
• Known allergy to clove, cinnamon, basil or balsam of Peru: cross-reactions are described.
• Dental treatment with zinc oxide eugenol cement: the same substance, a different context. Anyone who reacted there should mention it before colouring and styling.
• Products that stay on hair and skin: two of the four products in this record are styling products.

Open questions

• Concentration in the specific product: not available. It matters particularly here, because the eliciting amount can be very small.
• Frequency of a eugenol allergy in the general population: not quantified here. The study used worked with a group already known to be allergic.
• Why some of the confirmed allergic individuals do not react in the test: established in the study but not explained.
• Share of eugenol that enters the same formulation via clove oil or other essential oils: not readable. In an ingredient list the same substance can appear twice, once named and once as part of an oil.
• Regulatory status and the rules on individual naming: not checked; they are not quoted second-hand.

Sources for this assessment

• Ofenloch R. u. a.: Allergic reactivity for different dilutions of eugenol in repeated open application test and patch testing. Contact Dermatitis, 2023. 67 Personen aus sechs europäischen Hautkliniken; von 34 mit gesicherter Eugenol-Allergie reagierten 21 im Epikutantest und 19 im dreiwöchigen Anwendungstest, niedrigste auslösende Konzentration 0,031 Prozent. Begutachtete Fachzeitschrift, abgerufen am 11.09.2026.

Related substances

Applies to: Fragrance materials

• Alpha-Isomethyl Ionone — Fragrance
• Benzyl Salicylate — Fragrance
• Citral — Fragrance
• Citronellol — Fragrance

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