Comparison of patch testing Brazilian (Green) propolis and Chinese (poplar‐type) propolis: Clinical epidemiological study using data from the Information Network of Departments of Dermatology (IVDK)

Background Propolis types differ regarding their chemical composition. Objectives To compare patch test results based on Brazilian (Green) propolis with data based on Chinese (poplar‐type) propolis, and to evaluate the specifications of raw materials used for the PT preparations. Methods In the Information Network of Departments of Dermatology (IVDK), 1290 consecutive patients were patch tested with Brazilian (Green) propolis (NH400, SmartPractice Europe). Patch test reactivity was compared with results obtained with Chinese (poplar‐type) propolis (NA71, SmartPractice Europe) by calculating frequencies and corresponding 95% confidence intervals. Data on the specifications of raw materials used for NH400 and NA71 were obtained from the manufacturer. Results Positive reactions to NH400 were found in 303 (23.5%) patients with unclear clinical relevance in most cases. Patients reacting to NH400 were less often sensitised to fragrances and colophony, but more often to nickel sulphate and cobalt chloride than patients reacting to NA71. The NH400 batch used contained high levels of aerobic bacteria, and was not purified by ethanolic extraction. Conclusions Pattern of concomitant reactivity along with raw material properties suggests that the high frequency of positive reactions to NH400 may primarily result from bacterial contamination or impurities in the PT preparation rather than from propolis constituents.