LAUSR

Pentylene glycol (1,2-dihydroxypentane; CAS no. 5343-92-0) is a solvent, humectant, and preservative often used in cosmetics as an alternative to propylene glycol because, although it has similar structure and properties, it is considered to be associated with a lower risk of allergic and irritant skin reactions. Cross-reactivity between the 2 substances is possible, but our patient did not react to propylene glycol present in the cosmetic series. Reports of contact allergy to pentylene glycol are rare. To our knowledge, this preservative is not commercially available as a patch test allergen, and sensitization to it is likely to pass undetected unless specifically looked for. The severity of the clinical picture in our patient suggests that its allergenic potential may be stronger than hitherto suspected, particularly when it is contained in cosmetics meant for delicate areas such as the eyelids. Its inclusion in the list of substances under investigation as potential add-on allergens in cosmetic series might be warranted.