Sesquiterpene lactones and plants.

Four families of plants contain sesquiterpene lactones able to induce conta ct dermatitis, The chemical structure of these lactones can explain the pos sibility of cross-reactions between plants of very different species. Expos ure to sunlight accentuates the photosensitisation. The diagnosis can be es tablished by skin tests performed with the plant. A mixture of sesquiterpen e lactones was used for systematic surveys. This mixture allowed the aetiol ogical diagnosis of at least 30 % of cases of dermatitis due to plants cont aining sesquiterpene lactones.