ALLERGIC REACTIONS TO BENZALKONIUM CHLORIDE

This short paper reports positive patch test reactions to benzalkonium chloride (B) in patients treated with eyedrops preserved with this compound. A total of 100 patients treated by ophthalmologists in private practice with different eye preparations for chronic conjunctivitis for 3 months or longer were included in the study. They were patch tested with benzalkonium chloride 0.07% in aqueous solution. Six patients showed positive reactions, read at 48 and 72 h. All 6 patients showed positive patch test reactions in a serial dilution. Two of the six patients showed a positive reaction even to 0.005%. All of them had been using eyedrops preserved with B. It is known to us that at least some of the nonsensitized patients have been exposed to eyedrops preserved with B. None of the patients had eczema at the time of patch testing.