Background: Compositae dermatitis involves workers such as gardeners, florists, and farmers, and less commonly people not employed in occupations at risk.
Objective: To report a case of contact sensitization caused by Compositae, the source of sensitization being both pesticides and plants.
Methods: A 65-year-old man, whose hobby was gardening, was affected by a chronic eczema of the face and the hands for 6 months that reoccurred after using fertilizers and handling plants. Patch tests with the International Contact Dermatitis Research Group standard series, the plants series and pesticides series (Hermal Trolab) were performed.
Results: We found the following positive reactions at day 2 and day 3: sesquiterpene lactone mix, 0.1% in petrolatum; arnica tincture, 20% in petrolatum; pyrethrum, 2% in petrolatum; captafol, 0.1% in petrolatum.
Conclusion: Pyrethrum and its derivatives are made from Compositae plants; the arnica tincture is obtained from Arnica montana, which is also a member of the Compositae family. In our patient, the clinical manifestations were certainly caused by the exposure to sesquiterpene lactones, confirmed by the positive patch test to sesquiterpene lactone mix.