Benzalkonium chloride in nasal decongestive sprays has a long-lasting adverse effect on the nasal mucosa of healthy volunteers.

Twenty healthy volunteers participated in the present study on the long-term effects of a nasal decongestive spray composed of either a combination of oxymetazoline nasal spray and benzalkonium chloride or of oxymetazoline nasal spray alone. Three months before the present study the participants had undergone treatment with nasal decongestants for 4 weeks. Ten of the subjects had been treated with oxymetazoline nasal spray without benzalkonium chloride and 10 of them had been treated with oxymetazoline nasal spray with benzalkonium chloride. In a double-blind study the subjects who had been treated with oxymetazoline nasal spray and benzalkonium chloride were again treated with the same combination of substances as before, and the subjects who had been treated with oxymetazoline nasal spray alone were also treated again with oxymetazoline nasal spray alone, but on this occasion only for 10 days. Three variables were studied before and after the 10 days of treatment, i.e. nasal mucosa congestion, nasal reactivity and symptom scores. It was found that only the subjects who were treated with the combination of oxymetazoline nasal spray and benzalkonium chloride had increased nasal stuffiness, estimated by symptom scores and measurements of nasal mucosa swelling after 10 days of treatment. It is concluded that a nasal decongestant spray composed of a combination of vasoactive substance and benzalkonium chloride has a long-term adverse effect on the nasal mucosa.