During the past few years one of us has been patch-testing various types of skin conditions with a 10 per cent solution of nicotine salicylate and tobacco extract. At the Post Graduate Skin Clinic, a group of 43 cases has been tested, to date, including such conditions as dermatitis venenata, occupational dermatitis, etc. In this group there were many positive patch tests to other substances, but, it was astonishing to note, no really definite reactions to the relatively toxic nicotine solution. Two cases had a slight and ephemeral erythema at the test site. In spite of this apparent rarity of eczematous nicotine sensitizations, we have noted three strongly positive eczematous reactions to tests with tobacco extracts which were relatively nicotine free.
It is of interest to note that the only one of the patients with positive eczematous tobacco tests who could also be patch-tested to nicotine was absolutely negative to the alkaloid; and, furthermore, the patients with eczematous hypersensitivity to tobacco reacted only to some tobaccos and not to others.