Results of Patch Testing With a Brazilian Propolis Dilution Series

Abstract

Background: Patch testing with Brazilian propolis 10% pet. has yielded very high rates of positive reactions (> 20%). For most, no clinical relevance could be found. False-positive reactions from irritancy of the test material were suggested as a possible explanation.

Objectives: To assess whether positive patch test reactions to Brazilian propolis 10% pet. are allergic, irritant, or may be both.

Materials and methods: In a prospective study, consecutive patients suspected of contact dermatitis were patch tested with Brazilian propolis in a dilution series of 10%, 3.3% and 1% in petrolatum.

Results: Of 200 consecutive patients, 56 (28%) had one or more positive Brazilian propolis patch tests. Eighteen propolis-allergic individuals (32.1%) reacted only to the 10% concentration, 21 patients (37.5%) reacted to all 3 concentrations, 13 (23.2%) to 2 concentrations, and 4 (7.1%) to a lower concentration only. There was a strong association with fragrances, especially with the fragrance mixes 1 and 2.

Conclusions: Our data seem to indicate that the positive patch test reactions to Brazilian propolis 10% pet., or at least a large part thereof, are allergic in nature. Previous fragrance sensitisation may play an important role in the large number of positive patch tests to Brazilian propolis.

Keywords: Brazilian propolis; Chinese propolis; dilution series; false‐positive patch test reactions; irritancy; irritant patch test reactions; patch testing; propolis.