What it is
Linalool is an acyclic monoterpenoid (terpene alcohol) with the formula C10H18O that appears as a colorless oil. It occurs naturally in many flowers and spice plants and exists as two enantiomers with slightly different scent profiles: the S-form is sweet and floral while the R-form is more woody and lavender-like. In cosmetics it is used chiefly as a fragrance and masking ingredient to give or round out a product's scent.
Safety & warnings
Linalool is one of the fragrance substances that EU rules require to be labeled on cosmetics because it can cause allergic skin reactions in sensitized people. The risk is associated mainly with oxidized linalool, which forms when the ingredient is exposed to air; in European patch-test populations around 7% of those tested reacted to the oxidized form. People with fragrance allergies or reactive skin should be cautious with products containing it.
Origin & sourcing
Linalool is found naturally in over 200 plant species, including lavender, sweet basil, coriander, rosewood, and bay laurel, and can be obtained from their essential oils; S-linalool occurs in coriander and sweet orange flowers, while R-linalool is present in lavender and bay laurel. It is also produced synthetically for fragrance use, yielding material chemically identical to the natural compound.
History
Linalool is a long-recognized constituent of essential oils such as lavender and rosewood that has been characterized as a major contributor to their characteristic aromas. Its two enantiomers, sometimes called licareol and coriandrol after their plant sources, were distinguished by their distinct odor qualities.
Questions everyone asks
Why is linalool listed separately on the label?
EU cosmetic rules require linalool to be named on the ingredient list because it is a recognized fragrance allergen that can cause skin reactions in sensitized individuals.
Is linalool natural or synthetic?
Both. It occurs naturally in lavender, coriander, rosewood, and many other plants, and it is also produced synthetically for fragrance use.
Why can linalool cause skin reactions?
Linalool itself is a mild sensitizer, but its oxidation products, formed when it is exposed to air, are more likely to trigger allergic contact reactions in sensitized people.