Essential oils in cosmetics: INCI names, allergens and how to read them
Lavender, tea tree, orange peel, peppermint: essential oils appear on INCI lists under Latin botanical names, often followed by allergen names. How the naming works and what it tells you – and what it does not.
Updated: 31 October 2026 · Reviewed by: Kamil Pyziak
What an essential oil is
An essential oil is a concentrated, volatile mixture obtained from a plant, usually by steam distillation or, for citrus peels, by cold pressing. Despite the name, it is not a fatty oil like sunflower or jojoba oil: it evaporates, it smells strongly, and it consists of dozens or even hundreds of individual substances.
In cosmetics, essential oils are used mainly for scent, sometimes also with other functions listed in CosIng, such as “masking”, “tonic” or “skin conditioning”. Products that say “perfume-free” but contain essential oils are not unscented: the oils are a source of fragrance.
How essential oils are named in INCI
INCI names for plant materials follow a pattern: Latin genus and species, the part of the plant, and the type of material. Lavandula Angustifolia Oil is lavender oil; Melaleuca Alternifolia Leaf Oil is tea tree oil; Citrus Aurantium Dulcis Peel Oil is sweet orange peel oil; Mentha Piperita Oil is peppermint oil; Rosmarinus Officinalis Leaf Oil is rosemary oil; Eucalyptus Globulus Leaf Oil is eucalyptus oil.
Be careful not to confuse essential oils with fatty plant oils and extracts. Simmondsia Chinensis Seed Oil (jojoba) and Helianthus Annuus Seed Oil (sunflower) are fatty oils with little smell. Names ending in “Extract” or “Water” describe other preparations from the same plant, which may or may not be fragrant. The INCI name alone does not always reveal the method of production.
Why allergen names follow the oils
Many essential oils naturally contain substances that EU rules treat as fragrance allergens. Lavender oil contains linalool and linalyl acetate; orange and lemon peel oils are rich in limonene; clove oil contains eugenol; rose and geranium oils contain geraniol and citronellol. When these substances exceed the labelling thresholds – 0.001% in leave-on and 0.01% in rinse-off products – they must be named on the label, whatever their origin.
That is why a list may read “… Lavandula Angustifolia Oil, Linalool, Limonene, Geraniol”. The allergens are not added separately; they are declared because they are part of the oil. With Regulation (EU) 2023/1545, the list of fragrance allergens to be labelled has been considerably extended, so you may see more of these names on newer labels.
Oxidation and freshness
Some fragrance substances found in essential oils, notably limonene and linalool, react with air over time. Their oxidation products are known to be more likely to cause contact allergy than the fresh substances. Manufacturers often add antioxidants such as Tocopherol and use packaging that limits air contact.
For consumers this means that the age and storage of a product matter. The period-after-opening symbol (an open jar with a number of months) gives guidance on how long a product is intended to be used after opening; storing products closed and away from heat and light is sensible.
Citrus oils and light
Some cold-pressed citrus oils, bergamot in particular, can contain furocoumarins, substances that may make skin more sensitive to sunlight. EU rules restrict furocoumarins in cosmetics, and fragrance suppliers offer furocoumarin-free grades. The INCI name, such as Citrus Aurantium Bergamia Peel Oil, does not show which grade was used.
If a product label carries a warning about sun exposure, follow it. Reliable information on a specific product comes from the manufacturer; the ingredient list alone cannot answer it.
What the label does not tell you
The INCI list shows that an essential oil is present but not its amount, its chemical profile (which varies with plant variety, origin and harvest) or its processing. Allergens are named only above the thresholds. “Natural”, “pure” or “organic” on the pack says nothing about how well your skin will tolerate the oil.
If you know you react to a specific fragrance substance, look for its name in the list and also for oils known to contain it. A dermatologist can identify individual triggers by patch testing; with any persistent irritation, ask a pharmacist or doctor.