Anaphylactic reaction following administration of nose drops containing benzalkonium chloride

This is the first case described in the literature of an immediate-type (type I) allergic reaction to nose drops containing benzalkonium chloride. Benzalkonium chloride (N-alkyl-N-benzyl-N,N-dimethyl ammonium chloride) is a quaternary ammonium compound used, for instance, as a preservative agent in topical medications (eye and nose drops).A 46-year-old female patient presented in our outpatient department with an existing nasal respiration obstruction she had been experiencing for about 3？months with right-side preponderance, severe right-side facial pain and a subjectively reduced sense of smell. Surgical restoration of the right maxillary sinus was considered due to the ineffectiveness of the oral antibiotic and steroid treatments carried out to date. Six years earlier, the patient had undergone an endonasal septal deviation pansinus operation with septoplasty in the treatment of chronic ethmoid and maxillary sinusitis. In the years between this procedure and recurrence of the symptoms described above, the patient was otherwise free of symptoms, undergoing only various dental procedures.A rhinoscopic examination initially revealed nearly complete nasal obstruction by an inflammatory hyperplasia of the inferior turbinate on the right side and unremarkable findings on the left side. Further endoscopic examination revealed inflammatory narrowing of the right middle nasal meatus, with plentiful putrid secretion and polypoid mucosa in the area of the right ethmoid bone. The left middle nasal meatus was open and the septum position was median postoperatively. The remaining ENT findings were normal, in keeping with the patient's age. The findings from the computed tomography of the nasal sinuses done one week previously were of right-side sinusitis with a broad area of mucosal swelling around the fenestrated maxillary sinus as well as of the nasal cavity and the right-side portion of the sphenoid sinus and ethmoid cells. The images showed open nasal sinuses on the left s