Background: Ophthalmologists are not always aware of the hypersensitising potential of benzalkonium chloride (preservative widely used in ophthalmology).
Observations: Hypersensitivity to benzalkonium chloride was asserted by allergologic exploration in the three cases reported. Contact allergy, a frequent phenomenon, was diagnosed in two cases. The third case represents one of the few cases described in ophthalmology of immediate hypersensitivity associated to vital risk: chemosis and angioneurotic edema is reported in a woman who had been already presented an anaphylactic shock to a quaternary ammonium family anaesthetic.
Discussion: The ocular allergologic evaluation is specified. Risk to benzalkonium chloride sensitisation factors (ophthalmology, presence of benzalkonium chloride in numerous daily used products) are reviewed. The risk of severe immediate allergy is increased due to the relationship of benzalkonium chloride to other quaternary ammonium compounds.
Conclusion: Best risk prevention remains allergen eviction.