Linalool

Linalool is probably the single most widely used fragrance material in the world. It is the floral, slightly citrus note in lavender, in coriander seed, in bergamot, and in an enormous share of scented products.

Its story is the same as Limonene’s, which is why the two are almost always discussed together and why patch test panels treat them as a pair.

Fresh linalool is not the problem

As it comes, linalool is a weak sensitiser. On contact with air it oxidises into hydroperoxides, and those are the recognised allergens.

The European Society of Contact Dermatitis guideline records the pattern across both molecules: “limonene and linalool hydroperoxides have recently been found to be more common in the younger age groups, which underscores the burden of fragrance sensitization”.

More common in younger people is worth pausing on. That is not a statement about skin being more delicate. It is what you would expect if exposure has risen, which fits a generation using more scented products, more of them containing essential oils, over more years.

The consequence a label cannot carry

The product on your shelf is changing. Slowly, invisibly, and in the direction of being more likely to cause a reaction.

There is no way to read that off a pack. There is no oxidation date and the ingredient list names the precursor rather than what it has become. The period-after-opening symbol, the little jar with a number of months on European packaging, is the closest thing to a signal and it is about microbiological quality rather than this.

The practical response is dull and effective: smaller bottles, lids on, away from light and heat, and a willingness to throw out something scented that has been open for years.

Lavender is not a gentle category

Lavender is marketed as calming, and calming reads as gentle, and gentle reads as safe for reactive skin. The molecule doing the smelling is linalool.

Lavender oil, lavender water and lavender extract all carry it, and essential oils oxidise more readily than well-formulated synthetics because they are less stable and contain the terpenes in higher proportion.

None of this means lavender is harmful. It means that choosing a lavender product over a synthetically fragranced one, specifically to avoid fragrance allergens, does the opposite of what it is intended to do.

Where you will and will not see the name

European rules require certain fragrance substances to be named once they pass a threshold, so linalool appears at the end of European ingredient lists, usually next to limonene.

US rules allow the whole scent to be declared as fragrance. Same product, different amount of information, which is one of the clearest cases where reading the other market’s label is genuinely useful.

Reacting to one is not reacting to all

Fragrance is dozens of substances, and the baseline patch test series exists because reactions are specific. Someone sensitised to linalool hydroperoxides may be fine with a product scented entirely differently.

Cutting out all fragrance is a reasonable first move while you find out. It is not the necessary permanent conclusion, and a patch test is what converts a guess into an answer. The wider picture is on the fragrance allergy page.