Allergic contact dermatitis to Compositae: An Australian case series

BACKGROUND: Allergic contact dermatitis (ACD) to Compositae is caused by sensitisation to sesquiterpene lactones (SQLs) and subsequent exposure can occur from direct handling or from airborne transmission. Plants from the Compositae family are ubiquitous globally and their plant extracts are also used in various products. OBJECTIVES: Investigation of contact allergy (CA) and allergic contact dermatitis (ACD) to Compositae at a single dermatology centre. METHODS: A retrospective case review was performed on patients undergoing patch testing to Compositae between January 2011 and December 2020 in Melbourne, Australia. RESULTS: Of 3679 patients, 44 (1.2%) patch tested positive to Compositae and 19 (43.2%) reactions were deemed relevant. Thirteen cases (68.4%) were from direct contact with Compositae plants, mostly in gardeners. Six cases (31.6%) were from personal products and all these patients were female. Involvement of the face was significant (p = 0.007). Simultaneous allergic reactions included SQL mix in eight (42.1%), fragrance mix in seven (36.8%), potassium dichromate in three (15.8%) and colophonium in two (10.5%) cases. CONCLUSION: Contact with Compositae from gardening contributed most cases of ACD; however, personal products accounted almost one‐third of cases. Treatment options remain limited and avoidance is the most important aspect of management.