[Testing plant products brought in by patients]

Plant-induced dermatoses involve a variety of mechanisms and result from direct contact with the plant itself, part of the plant or an extract thereof; they may also involve phototoxic or photoallergic reactions. Subjects most exposed are woodworkers, agricultural workers, orchard workers, gardeners, etc. However, many subjects are also exposed during leisure activities (fishing, country walks, gardening, sports, etc.). History-taking is thus essential before beginning testing in order to establish any differential diagnoses. Tests consist of challenges using commercially available allergens, patch-tests using the plant itself or plant extracts, and skin prick-tests or photopatch-tests.