When fragrance ingredients linalool and limonene oxidize (break down over time), they can trigger allergic contact dermatitis. In patch tests of nearly 3,000 dermatitis patients across 6 countries, about 6% reacted to oxidized linalool and 5% to oxidized limonene—but only 25% of allergic patients reacted to both, meaning most people were sensitized to one or the other, not both.

Researchers patch-tested oxidized forms of linalool and limonene on 2,900 consecutive dermatitis patients across Australia, Denmark, Singapore, Spain, Sweden, and the UK to see how many had allergic reactions and whether reactions overlapped.

Funding not disclosed in abstract