Nasal Sprays

• Nasal decongestant sprays are used to gain relief from colds and runny noses. Benzalkonium chloride is a common ingredient in these sprays as a preservative and because it can kill bacteria by damaging their cell walls. However, benzalkonium chloride is toxic to beneficial cells as well.
  
  

Nasal Cilia

• The concentrations of benzalkonium chloride found in nasal decongestant sprays are toxic to the nasal cilia, the cells that move mucus through the nose and respiratory tract. They defend the respiratory system against infection. Damaging these cilia allows bacteria and viruses to enter the body more easily.
  
  

Rhinitis Medicamentosa

• Nasal decongestants can cause rhinitis medicamentosa (RM). In RM, more and more nasal decongestant must be used to keep the patient decongested, as the patient develops a tolerance for the decongestant. This effect is more severe in the presence of benzalkonium chloride. To avoid this effect, patients should take care not to exceed the recommended use of the nasal decongestant spray.