Fragrance Contact Allergy: What the European Numbers Show

Abstract

About one in twenty adults in Europe has a contact allergy to fragrance materials. Among people already attending a dermatology clinic with dermatitis, sensitisation to the standard fragrance marker runs to roughly one in five.

The mechanism behind a large share of it is not what most people assume. Two of the most common culprits are barely allergenic as manufactured. They become sensitisers after exposure to air.

Senses is a cosmetic containing lavender and bergamot essential oils. This article is about the risk that carries, published by us rather than found by a reader elsewhere.

1.The Scale

Thanaporn Sukakul, Magnus Bruze and Cecilia Svedman at Lund University reviewed fragrance contact allergy with a focus on patch testing, in Acta Dermato-Venereologica in 2024.

Their headline population figure: prevalence of fragrance contact allergy in the general population was 4.5 per cent in Europe during 2008 to 2011, when people were patch tested with several fragrance markers.

Those markers include fragrance mix I, Myroxylon pereirae resin — Balsam of Peru — colophonium, fragrance mix II, and a compound abbreviated HICC that has since been restricted in the European Union.

Among dermatitis patients the figures are much higher: prevalence to fragrance mix I has been reported up to about 20 per cent. Treemoss absolute, tested at one per cent in petrolatum, accounts for a further two to three per cent in dermatitis patients across Europe and Asia.

The authors add a caution we should pass on. Reported prevalence depends on which substances a clinic includes as fragrance markers, and those differ between clinics and studies. These numbers are real and they are not precise.

2.The Mechanism Almost Nobody Explains

This is the part that changes how a product should be handled, and it turns on a distinction between a prehapten and a hapten.

A hapten is the small molecule that actually binds skin proteins and triggers sensitisation. A prehapten is a substance that is not itself a sensitiser but becomes one through chemical change outside the body.

Linalool and limonene — two of the most widespread fragrance materials, both present in lavender oil — are prehaptens. In the words of the review: linalool itself is a prehapten that is non- or low-allergenic, but can be oxidised when exposed to air and transformed into several potential skin sensitizers.

The resulting compounds, the hydroperoxides of linalool and limonene, are common enough to have their own collective name in the literature: oxidised terpene fragrances.

So the allergen is largely not what is put into the bottle. It is what forms in the bottle, and on the skin, as the oil meets air over time.

3.What Follows Practically

Three things, and none of them appear on most packaging.

An old, half-empty, frequently opened bottle of an essential oil is chemically not the same product as a new one. Air is the reagent, and headspace and opening frequency are what determine exposure.

Patch testing with the pure ingredient can miss the problem. If a clinic tests unoxidised linalool, someone sensitised to its hydroperoxides may test negative — which is precisely why oxidised forms have been added to testing series.

And natural provides no protection whatsoever. Linalool and limonene are plant-derived, which is why they are in essential oils in the first place, and the oxidation chemistry does not care about the source.

4.What the Safety System Does and Does Not Do

Fragrance safety is not unregulated. Mihwa Na and colleagues, writing in Dermatitis in 2021, summarise thirty years of fragrance skin sensitisation evaluation and human testing, describing an established framework for assessing materials before use.

Wolfgang Uter, Thomas Werfel, Jean-Pierre Lepoittevin and Ian White set the wider context in a 2020 review of emerging allergens and public health impact, and the framing of that title is the relevant part: contact allergy is treated as a public health matter, not merely an individual misfortune.

In the European Union, specified fragrance allergens must be declared by name on cosmetic labels above set concentration thresholds, under Regulation (EC) 1223/2009. That is the system working — but it places the burden of recognition on a consumer reading an ingredient list, which requires knowing that linalool on a label is a thing worth knowing about.

Sensitisation is also, once established, generally permanent. This is not an intolerance that fades with avoidance; it is an immunological memory. That asymmetry is the reason we think a first-time user deserves the information before rather than after.

5.Who Should Be Careful

Anyone with existing eczema or atopic dermatitis, because a compromised barrier increases both exposure and risk, and because prevalence in this group is several times higher than in the general population.

Anyone who has previously reacted to a scented product, since fragrance allergens cross between cosmetics, detergents and household products.

And anyone applying an oil to a large area, to broken skin, or repeatedly to the same site — all of which increase dose in a way a single patch does not.

A persistent, itching, spreading rash after using a scented product is worth a dermatologist rather than a different product. Patch testing identifies the specific allergen, which is the only thing that makes reliable avoidance possible — and guessing at the culprit from an ingredient list is considerably less effective than testing for it.

Editorial Comment

Senses is a cosmetic containing lavender and bergamot essential oils in a carrier base. It is not a supplement, and no health claim of any kind may be made for it — including anything about sleep, calm or anxiety.

We are publishing the risk literature for a category we sell into, and we want to be plain about why. A brand that only publishes the pleasant half of the evidence about its own product is not running a library; it is running a longer advertisement.

Concretely: if you have eczema, or have reacted to scented products before, this is a product to approach cautiously or not at all. If you use it, a small test area first is sensible, and an old bottle is a worse bet than a new one for reasons set out in section two.

One thing this article does not cover. Bergamot oil carries a separate and different risk — furocoumarin phototoxicity, which is about sunlight rather than allergy and produces burns rather than dermatitis. We have not yet been able to obtain readable full texts of the primary literature on it, and we would rather say that than write about papers we have only seen abstracts of. It remains in our queue.