What Is Lavender Oil, What Does It Do? Linalool and Sensitivity

What we call lavender oil is not a single ingredient; its composition varies markedly depending on the plant species used. The species most often found in cosmetics is Lavandula angustifolia, written on labels as Lavandula Angustifolia (Lavender) Oil, and its role is mostly to provide scent. Adding it to care products labelled "soothing" is another matter, because the effect of the scent on the brain and its effect on the skin itself do not rest on the same data.

Which lavender, which composition?

The table shows that two "lavender" oils can be chemically different products. Do not read a study done on one species as a benefit of the other. Look for the Latin name in the ingredient list, and remember that proportions can vary between batches of the same product.

How strong is the soothing claim?

Part of the evidence relates to scent, and here the data are better in terms of the skin. In 20 healthy volunteers, lavender scent reduced blood pressure and heart rate, and people felt more relaxed. A meta-analysis reports that lavender is better than placebo or no application for anxiety, but the studies are small and different from each other. In these data, oral capsules and inhalation are combined; no study directly compares the two. If you have persistent anxiety or insomnia, consult a doctor rather than relying on the oil.

The skin side is weaker. In rats wound closure was accelerated; in a mouse psoriasis model, 10% oil reduced signs of disease, but the same concentration caused mild irritation. We know of no controlled study showing it soothes human skin. In cell culture, oil at a concentration as low as 0,25% damaged human skin cells. This alone does not mean it is harmful on the skin, but it is inconsistent with the claim that it can be applied neat.

Where does the risk come from?

The main problem is oxidation. Both main components of the oil break down with air and turn into stronger allergens:

• Pure linalyl acetate is a weak sensitiser in mouse testing (effective concentration 25%); when oxidised for 10 weeks, the concentration falls to 3,6%, meaning about 7 times stronger.
• In a patch test of 2.900 dermatitis patients in six countries, oxidised linalool gave a positive reaction in 6,9% of them. This is a selected group of patients and cannot be carried over to the general population.

The labelling rule also reflects this. Linalool is already a substance that must be named separately; and with the 2023 EU regulation, lavender oil and extract were added to this list. The limit is 0,001% in leave-on products and 0,01% in rinse-off products. Reported cases of breast tissue growth in children and the general essential oil risks are covered in the perfume and essential oils article.

If you are going to use it, what should you watch for?

• Do not apply pure oil directly to the skin. We do not know a measured safe dilution for home use; a ready product with a stated proportion is more predictable.
• Store it in a dark bottle, with the cap closed, in a cool place. Do not use a bottle that has been open for a long time on the skin.
• Do not use it on your own during pregnancy and breastfeeding, on small children, or if you have eczema, without consulting your doctor.
• A rinse-off product touches the skin less and carries lower risk than a product left on all day. Test the new product first on the inner arm or elbow crease, twice a day, for 7-10 days.