Allergic contact dermatitis from eosin.

Before 1960, eosin sensitivity was not rare and lipstick cheilitis was very common. We report 4 patients seen in 1988 and 1989 who were sensitized to eosin from topical bacteriostatic preparations. All 4 patients had positive patch tests to eosin. The allergen is probably an impurity rather than eosin itself.