Compositae dermatitis in a Danish dermatology department in one year (I). Results of routine patch testing with the sesquiterpene lactone mix supplemented with aimed patch testing with extracts and sesquiterpene lactones of Compositae plants.

To investigate the frequency of Compositae sensitivity, the recently-developed sesquiterpene lactone mix (SL mix) was included in the standard patch test series. Patients with positive reactions to this or patients suspected of having a Compositae allergy were supplementarily tested with a Compositae mix, consisting of ether extracts of 5 European Compositae plants. In the first year, 686 patients were tested with the SL mix and 79 with the Compositae mix. A total of 31 Compositae-sensitive patients (4.5%) were found. The frequency of positive reactions to either of the mixes was equal, but only 17 of 30 patients tested were positive to both mixes. Testing with the individual ingredients of the Compositae mix showed frequent positive patch test reactions to feverfew, followed in order by chamomile, tansy, yarrow and arnica. The reason for this distribution is discussed and the results of standard, photo- and other plant patch tests are presented. The only partial overlap between positive reactions to the mixes emphasizes the necessity of supplementary testing in patients suspected of Compositae allergy, as well as the lack of a reliable single screening agent. Since no cases of active sensitization or irritant reactions were seen, both the SL mix and the Compositae mix may be considered suitable for routine screening of Compositae allergy.