Linalool, limonene, citral, geraniol: what fragrance allergens on the label mean
Linalool, Limonene, Citral and Geraniol are some of the most common names at the end of an ingredient list. What each of them is, where it occurs in nature, why it is named separately – and what its presence does and does not tell you.
Updated: 31 October 2026 · Reviewed by: Kamil Pyziak
Why these names follow “Parfum”
A fragrance is declared on the ingredient list with one word, Parfum. In the EU, however, certain fragrance substances known to cause contact allergy in some people must also be named individually when their concentration exceeds a threshold – 0.001% in leave-on and 0.01% in rinse-off products. That is why lists often end with “Parfum, Linalool, Limonene, Citral, Geraniol”.
“Allergen” in this context does not mean that the product is unsafe or that everyone will react. It means that the substance is on a regulatory list of fragrance ingredients that can trigger contact allergy in sensitised people, so that those people can find and avoid it. Since Regulation (EU) 2023/1545 the list has grown considerably, so newer labels may show more names than before.
Linalool and limonene: the most frequent pair
Linalool has a fresh, floral, slightly woody scent. It is a major component of lavender oil and is also found in coriander, bergamot and many flowers and herbs; it is also produced synthetically. Limonene is the typical smell of citrus peel and makes up a large part of orange and lemon peel oils. Both are used in perfumes, shampoos, creams and household products.
Fresh linalool and limonene are considered relatively weak sensitisers. On contact with air, however, they gradually oxidise, and some of the oxidation products are considerably more likely to cause contact allergy. That is why formulators protect them with antioxidants such as Tocopherol, and why dermatologists can include oxidised linalool and limonene in patch tests.
Citral, geraniol and citronellol: lemon and rose
Citral is not a single molecule but a mixture of two closely related ones, geranial and neral. It smells intensely of lemon and is abundant in lemongrass and Litsea cubeba oil, with smaller amounts in lemon oil. It is a common reason why lemon-scented products list allergens even when they contain no added perfume.
Geraniol and Citronellol have rosy scents and often appear together. They occur in rose, geranium and palmarosa oils, and geraniol also in citronella oil. Like linalool, they are used both as synthetic fragrance materials and as natural parts of essential oils; the label does not distinguish between the two.
Other names you will meet
Coumarin smells sweet, of hay or vanilla, and occurs in tonka beans. Eugenol is the warm, spicy note of clove; Isoeugenol is related and has a carnation-like scent. Cinnamal is the main aroma molecule of cinnamon. Hexyl Cinnamal (jasmine-like), Alpha-Isomethyl Ionone (violet-like), Benzyl Salicylate and Benzyl Benzoate are widely used synthetic or nature-identical materials. Evernia Prunastri Extract is oakmoss, a natural extract also on the list.
Some former fragrance ingredients are no longer allowed in EU cosmetics. Butylphenyl Methylpropional (known as lilial) has been prohibited since March 2022 after being classified as toxic for reproduction, and Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde (known as lyral) was banned because of its allergy potential. You may still find them on older products or on labels from outside the EU.
What their presence means – and what it does not
A named allergen tells you that the substance is present above the labelling threshold. It does not say how much is in the product, and its position at the end of the list usually reflects a small amount. A long list of allergens does not automatically mean a stronger or more irritating fragrance: a product scented with a single essential oil can trigger several names, because each oil is a mixture of many substances.
Contact allergy develops through sensitisation, usually after repeated exposure. Most people use products containing these substances without problems. For someone who is already sensitised to a specific substance, however, even small amounts can matter, and that person needs to look for the exact name. Natural or synthetic origin makes no difference: the molecule is the same.
Practical reading tips
If a dermatologist has identified a specific fragrance allergen for you, search every ingredient list for that exact INCI name, including in rinse-off products such as shampoos and shower gels. Also consider essential oils that are naturally rich in it: lavender oil for linalool, citrus peel oils for limonene, lemongrass for citral, rose and geranium oils for geraniol and citronellol, clove oil for eugenol.
Remember that some of these substances also have other functions. Benzyl Alcohol, for example, is often used as a preservative and is also listed as a fragrance allergen. A product without “Parfum” can therefore still contain a named allergen.
What the label does not tell you
The label names allergens only above the thresholds; smaller amounts do not have to appear. It does not show the exact concentration, whether a substance came from an essential oil or from synthesis, or how much it has oxidised in an opened product – which depends on age, storage and packaging.
Above all, an ingredient list cannot tell you whether you personally are sensitised to anything. If you notice redness, itching or a rash after using a product, stop using it and ask a pharmacist or doctor; only patch testing by a dermatologist can identify the substance responsible.