Limonene and linalool hydroperoxides review: Pros and cons for routine patch testing.

Limonene and linalool are among the most common fragrance terpenes used in everyday products. They are pre-haptens, forming hydroperoxides (Lim-OOHs, Lin-OOHs) upon oxidation and inducing frequent positive patch test reactions in patients with dermatitis, and yet they are not routinely tested in Europe. This review evaluates current patch testing with Lim-OOHs and Lin-OOHs by asking whether hydroperoxide patch testing is warranted, examining the difficulties or challenges related to reading and interpreting hydroperoxide patch test results with currently available material, and assessing their relevance.