Fixed eruption due to quinine: report of two cases.

Fixed eruption is a characteristic condition with recurrent an erythematous macule in the same location. Because fixed eruption is caused by medical drugs in the majority of cases, it is not so difficult to identify suspicious material by interview. However, it may be difficult in cases in which food additives are responsible. We report two rare cases of fixed eruption due to quinine contained in tonic water. In case 1, a 37-year-old man had repeated erythema on the same sites after drinking a variety of cocktails. We suspected tonic water as the causative material. Oral challenge test of tonic water was positive and patch test with quinine sulfate was positive also. In case 2, a 24-year-old woman in had noticed that her eruption appeared after drinking liquor, especially cocktails as in case 1. She was also positive upon an oral challenge test of tonic water and in a patch test of quinine sulfate.